JP4978513B2 - Engine gas leak detection device - Google Patents

Description

  The present invention relates to an engine gas leak detection apparatus.

  A characteristic change substance whose characteristic changes by reacting with at least one of the components to be purified in the exhaust is placed in the part where the exhaust gas leak occurs, and the exhaust gas leak is detected based on the change in the characteristic of the characteristic change substance. The technique to do is disclosed (for example, refer patent document 1).

  A technique for determining a gas leak of exhaust gas based on a detection value of an oxygen concentration sensor arranged in an exhaust system is disclosed (for example, see Patent Document 2).

  A technique is disclosed in which a hydrogen concentration sensor is installed in a case where a fuel cell stack or the like is disposed, and a gas leak of hydrogen gas is detected based on a detection value of the hydrogen concentration sensor (see, for example, Patent Document 3). .

  A technique for determining the gas leakage of the EGR gas of the EGR device based on the degree of change of the air-fuel ratio of the exhaust gas according to the opening degree of the EGR valve of the EGR device is disclosed (for example, see Patent Document 4).

A technique for detecting a gas leak from intake air from an intercooler based on a change in intake air pressure and notifying the user is disclosed (for example, see Patent Document 5).
Japanese Patent Laid-Open No. 2007-9880 JP 10-47130 A JP 2006-318817 A JP 2006-257881 A JP 58-35226 A

  By the way, the engine may be provided with a low pressure EGR device that takes in a part of the exhaust gas from the exhaust system downstream of the turbine as low pressure EGR gas and recirculates the low pressure EGR gas to the intake system upstream of the compressor. When this low pressure EGR device is provided, low pressure EGR gas is supplied to the intake system upstream of the compressor. When an intake gas leaks from the intake system to which the low-pressure EGR gas is supplied, the low-pressure EGR gas, that is, exhaust gas, is included in the gas leaking from the intake system into the engine room. In this way, exhaust gas may leak not only from the exhaust system but also from the intake system. Since exhaust gas contains components to be purified such as PM and NOx, if the exhaust gas leaks, the environment will be adversely affected. For this reason, it is desirable to find out an exhaust gas leak at an early stage.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technology for early detection of gas leakage including exhaust from an intake system or an exhaust system in an engine gas leak detection device. There is.

In the present invention, the following configuration is adopted. That is, the present invention
An engine located in the engine room;
An intake system and an exhaust system connected to the engine;
An exhaust supply means for supplying exhaust discharged from the engine to the intake system;
An oxygen concentration detection device arranged in the engine room for detecting the oxygen concentration of the gas in the engine room;
Determining means for determining that a gas leak has occurred from the intake system or the exhaust system based on the oxygen concentration of the gas in the engine room detected by the oxygen concentration detection device;
An engine gas leak detection device characterized by comprising:

  The exhaust from the engine exhaust system may leak into the engine room. On the other hand, when an exhaust gas supply means for supplying the exhaust gas discharged from the engine to the intake system of the engine is provided, the exhaust gas is included in the gas leaking from the intake system into the engine room. In this way, exhaust gas may leak not only from the exhaust system but also from the intake system. Since exhaust gas contains components to be purified such as PM and NOx, if the exhaust gas leaks, the environment will be adversely affected. For this reason, it is desirable to detect and deal with exhaust gas leaks at an early stage.

  Therefore, in the present invention, it is determined that a gas leak has occurred from the intake system or the exhaust system based on the oxygen concentration of the gas in the engine room detected by the oxygen concentration detection device.

  According to the present invention, gas leakage including exhaust from the intake system or the exhaust system can be detected at an early stage. Therefore, it is possible to cope with gas leaks at an early stage, and it is possible to suppress exhaust gas from leaking and adversely affecting the environment.

  The determination unit may determine that a gas leak has occurred from the intake system or the exhaust system when the oxygen concentration of the gas in the engine room detected by the oxygen concentration detection device is equal to or lower than a first predetermined concentration.

  Here, the first predetermined concentration is a concentration that is not possible in the normal atmosphere when the oxygen concentration is lower than that, and is a concentration generated by mixing exhaust gas leaked from the intake system or the exhaust system with the gas in the engine room.

  According to the present invention, it is possible to uniformly determine that a gas leak including exhaust from the intake system or the exhaust system has occurred.

  The exhaust supply means is an EGR device that takes in a part of exhaust gas from the exhaust system as EGR gas and recirculates the EGR gas to the intake system, and the determination means includes gas leakage from the intake system or the exhaust system. The gas in the engine room detected by the oxygen concentration detection device after a lapse of a predetermined time after stopping the reflux of the EGR gas using the EGR device when the EGR gas is stopped. If the oxygen concentration is greater than or equal to a second predetermined concentration, it is determined that a gas leak has occurred from the intake system, and if it is lower than the second predetermined concentration, a gas leak has occurred from the exhaust system. It is good to judge.

  Here, when the predetermined time is after the elapse of the time, when the intake air containing the EGR gas leaks, the recirculation of the EGR gas is stopped, so that the oxygen concentration of the gas in the engine room becomes atmospheric. This is the time that changes so as to approach the oxygen concentration.

  Further, if the second predetermined concentration is an oxygen concentration higher than that, when the intake air containing the EGR gas leaks, the recirculation of the EGR gas is stopped, so that the oxygen concentration of the gas in the engine room is reduced to the atmosphere. It is a concentration that changes to approach the oxygen concentration of the gas and indicates that a gas leak has occurred from the intake system, and if the oxygen concentration is lower than that, the gas in the engine room is stopped even if the recirculation of EGR gas is stopped This is a concentration indicating that the exhaust gas was leaking because the oxygen concentration did not approach the oxygen concentration in the atmosphere and a gas leak occurred from the exhaust system.

  According to the present invention, exhaust gas is included in the intake air flowing through the intake system by recirculating the EGR gas to the intake system using the EGR device. As a result, exhaust gas is included in the gas leaking from the intake system into the engine room. According to the present invention, it is possible to detect at an early stage whether the gas leakage includes exhaust from either the intake system or the exhaust system.

  A turbocharger having a turbine disposed in the exhaust system and a compressor disposed in the intake system, wherein the EGR device takes a part of the exhaust as low-pressure EGR gas from the exhaust system downstream from the turbine; A low-pressure EGR device that recirculates the low-pressure EGR gas to the intake system upstream from the compressor may be used.

  According to the present invention, the low pressure EGR gas is recirculated to the intake system upstream of the compressor using the low pressure EGR device, so that the exhaust gas is included in the intake air flowing through the intake system upstream of the compressor. As a result, exhaust gas is included in the gas leaking from the intake system upstream of the compressor into the engine room.

  The oxygen concentration detection device may be arranged in the vicinity of the intake system in the engine room.

  According to the present invention, when a gas leak including exhaust from the intake system occurs, the oxygen concentration detection device can early detect a change in the oxygen concentration of the gas in the engine room.

  An intercooler for cooling the intake air flowing through the intake system may be provided, and the oxygen concentration detection device may be disposed in the vicinity of the intercooler in the engine room.

  According to the present invention, when a gas leak including exhaust from the intercooler occurs, the oxygen concentration detection device can early detect a change in the oxygen concentration of the gas in the engine room.

  The oxygen concentration detection device includes an inner detection unit that detects an oxygen concentration of exhaust gas flowing through the exhaust system, and oxygen in the engine room that is outside the exhaust system for zeroing the inner detection unit It is good that it is the said outer side detection part of the detection apparatus which has an outer side detection part which detects a density | concentration.

  According to the present invention, it is possible to detect the oxygen concentration of the gas in the engine room by using a detection device having an inner detection unit and an outer detection unit.

  The determination means may stop the recirculation of EGR gas using the EGR device when it is determined that gas leakage has occurred from the intake system.

  According to the present invention, although there is a gas leak from the intake system, there is no exhaust leak from the intake system, and the engine can be continuously operated.

  According to the present invention, in an engine gas leak detection device, a gas leak including exhaust from an intake system or an exhaust system can be detected at an early stage.

  Specific examples of the present invention will be described below.

<Example 1>
FIG. 1 is a diagram illustrating a schematic configuration of an engine to which the gas leak detection apparatus for an engine according to the present embodiment is applied and an intake system / exhaust system thereof. The engine 1 shown in FIG. 1 is a water-cooled four-stroke cycle diesel engine having four cylinders. In each cylinder, fuel is injected from the fuel injection valve. The engine 1 is mounted on a vehicle and is installed in an engine room 2 of the vehicle. An intake passage 3 and an exhaust passage 4 are connected to the engine 1.

  In the middle of the intake passage 3 connected to the engine 1, a compressor 5 a of a turbocharger 5 that operates using exhaust energy as a drive source is disposed. A first throttle valve 6 for adjusting the flow rate of intake air flowing through the intake passage 3 is disposed in the intake passage 3 upstream of the compressor 5a. The first throttle valve 6 is opened and closed by an electric actuator. An air flow meter 7 that outputs a signal corresponding to the flow rate of fresh air flowing through the intake passage 3 is disposed in the intake passage 3 upstream of the first throttle valve 6. The air flow meter 7 measures the intake air amount (fresh air amount) taken into the engine 1.

  An intercooler 8 that performs heat exchange between the intake air and the outside air is arranged in the intake passage 3 downstream of the compressor 5a. A second throttle valve 9 that adjusts the flow rate of the intake air flowing through the intake passage 3 is disposed in the intake passage 3 downstream of the intercooler 8. The second throttle valve 9 is opened and closed by an electric actuator. The intake passage 3 and the devices arranged in the intake passage 3 constitute an intake system for taking intake air into the engine 1.

  On the other hand, a turbine 5 b of the turbocharger 5 is disposed in the middle of the exhaust passage 4 connected to the engine 1. An exhaust purification device 10 is disposed in the exhaust passage 4 downstream of the turbine 5b. The exhaust purification device 10 includes an oxidation catalyst and a diesel particulate filter (hereinafter simply referred to as a filter) disposed at a subsequent stage of the oxidation catalyst. The filter carries a NOx storage reduction catalyst (hereinafter simply referred to as NOx catalyst).

  An oxygen concentration detection sensor 11 is disposed in the exhaust passage 4 downstream of the exhaust purification device 10. The oxygen concentration detection sensor 11 detects the oxygen concentration of the exhaust discharged from the exhaust purification device 10. As shown in FIG. 2, the oxygen concentration detection sensor 11 includes an inner detection portion 11a that actually detects the oxygen concentration of the exhaust gas flowing through the exhaust passage 4, and an exhaust passage for zeroing (calibration) of the inner detection portion 11a. 4 is an outside detection unit 11b that detects the oxygen concentration of the gas in the engine room 2 that is outside the engine. The outer side detection part 11b of the oxygen concentration detection sensor 11 in a present Example corresponds to the oxygen concentration detection apparatus of this invention. In this way, by using the outer detection unit 11b of the oxygen concentration detection sensor 11 as an oxygen concentration detection device, it is not necessary to provide another oxygen concentration detection device, and the number of parts does not increase. And since the number of parts does not increase, an increase in cost can be suppressed. The exhaust passage 4 and the devices arranged in the exhaust passage 4 constitute an exhaust system for exhausting exhaust from the engine 1.

  The engine 1 is provided with a low pressure EGR device 30 that recirculates (recirculates) a part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3 at a low pressure. In this embodiment, the exhaust gas recirculated by the low pressure EGR device 30 is referred to as low pressure EGR gas.

  The low pressure EGR device 30 includes a low pressure EGR passage 31 through which the low pressure EGR gas flows, a low pressure EGR valve 32 that adjusts a flow rate of the low pressure EGR gas that flows through the low pressure EGR passage 31, a low pressure EGR cooler 33 that cools the low pressure EGR gas, and Have.

  The low pressure EGR passage 31 includes an exhaust passage 4 downstream of the exhaust purification device 10 and upstream of the oxygen concentration detection sensor 11, and an intake passage 3 upstream of the compressor 5a and downstream of the first throttle valve 6. Connected. Through this low-pressure EGR passage 31, the exhaust is sent to the engine 1 at a low pressure as low-pressure EGR gas.

  The low-pressure EGR valve 32 is disposed in the low-pressure EGR passage 31 downstream of the low-pressure EGR cooler 33, and adjusts the passage cross-sectional area of the low-pressure EGR passage 31, thereby adjusting the flow rate of the low-pressure EGR gas flowing through the low-pressure EGR passage 31. To do. The low pressure EGR valve 32 is opened and closed by an electric actuator. The low-pressure EGR gas flow rate can be adjusted by a method other than the adjustment of the opening degree of the low-pressure EGR valve 32. For example, by adjusting the opening of the first throttle valve 6 or by adjusting the opening of an exhaust throttle valve (not shown), the differential pressure between the upstream and downstream of the low pressure EGR passage 31 is changed. The flow rate of the low pressure EGR gas can be adjusted.

  The low pressure EGR cooler 33 is disposed in the middle of the low pressure EGR passage 31. The low-pressure EGR cooler 33 exchanges heat between the low-pressure EGR gas passing through the low-pressure EGR cooler 33 and the engine cooling water, and lowers the temperature of the low-pressure EGR gas.

  On the other hand, the engine 1 is provided with a high-pressure EGR device 40 that recirculates (recirculates) a part of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3 at a high pressure. In the present embodiment, the exhaust gas recirculated by the high pressure EGR device 40 is referred to as high pressure EGR gas.

  The high pressure EGR device 40 includes a high pressure EGR passage 41 through which the high pressure EGR gas flows, and a high pressure EGR valve 42 that adjusts the flow rate of the high pressure EGR gas through the high pressure EGR passage 41.

  The high-pressure EGR passage 41 connects the exhaust passage 4 upstream of the turbine 5 b and the intake passage 3 downstream of the second throttle valve 9. Through this high-pressure EGR passage 41, the exhaust is sent to the engine 1 at high pressure as high-pressure EGR gas.

  The high-pressure EGR valve 42 is disposed in the high-pressure EGR passage 41 and adjusts the flow rate of the high-pressure EGR gas flowing through the high-pressure EGR passage 41 by adjusting the passage cross-sectional area of the high-pressure EGR passage 41. The high pressure EGR valve 42 is opened and closed by an electric actuator. The adjustment of the high-pressure EGR gas flow rate can also be performed by a method other than the adjustment of the opening degree of the high-pressure EGR valve 42. For example, by adjusting the opening degree of the second throttle valve 9, the differential pressure between the upstream and downstream of the high pressure EGR passage 41 can be changed, thereby adjusting the flow rate of the high pressure EGR gas. When the turbine 5b of the turbocharger 5 is a variable capacity type, the amount of high-pressure EGR gas can be adjusted also by adjusting the opening degree of the nozzle vane that changes the flow rate characteristic of the turbine 5b.

  By providing the low-pressure EGR device 30 and the high-pressure EGR device 40 as described above, the intake system is recirculated to the intake system by using both EGR devices to recirculate low-pressure EGR gas or high-pressure EGR gas (also referred to as EGR gas). Exhaust is included in the circulating intake air. As a result, there is a case where exhaust gas is included in the gas leaking from the intake system into the engine room 2.

  Note that the low-pressure EGR device 30 and the high-pressure EGR device 40 are not only provided with both as in the present embodiment, but may be provided with either the low-pressure EGR device 30 or the high-pressure EGR device 40. The low pressure EGR device 30 and the high pressure EGR device 40 in the present embodiment correspond to an EGR device, and in a broad sense, correspond to the exhaust gas supply means of the present invention.

  The engine 1 configured as described above is provided with an ECU 12 that is an electronic control unit for controlling the engine 1. The ECU 12 is a unit that controls the operating state of the engine 1 in accordance with the operating conditions of the engine 1 and the driver's request.

The ECU 12 is connected to the air flow meter 7 and the inner detection unit 11a and the outer detection unit 11b of the oxygen concentration detection sensor 11 through electric wiring, and output signals from these various sensors are input to the ECU 12. .

  On the other hand, the actuators of the first throttle valve 6, the second throttle valve 9, the low pressure EGR valve 32, and the high pressure EGR valve 42 are connected to the ECU 12 through electric wiring, and these devices are controlled by the ECU 12. Is done.

  The ECU 12 receives the output signals from the crank position sensor 13 and the accelerator position sensor 14, etc., determines the operating state of the engine 1, and electrically controls the engine 1 and the above devices based on the determined engine operating state.

  By the way, the exhaust gas from the exhaust system of the engine 1 may leak into the engine room 2.

  On the other hand, when the low-pressure EGR gas that is exhaust gas is cooled as in the low-pressure EGR device 30, acidic condensed water may be condensed and corrosion may occur due to acidic condensed water in the intake system. At this time, depending on the environmental conditions such as the use of fuel with a high sulfur content or strong oxidation due to the concentration of acidic condensate, the corrosive environment is dramatically deteriorated, which greatly adversely affects the reliability of intake system components. Effect. In addition, there is a risk of causing gas leakage of the intake air in the intake system. In particular, the intercooler 8 made of an aluminum material arranged in the intake system is significantly corroded.

  Here, as long as the intake system takes in only fresh air as in the prior art, even if an intake gas leaks from the intake system such as the intercooler 8, it does not become a big problem.

  However, when the low-pressure EGR device 30 or the high-pressure EGR device 40 that supplies exhaust gas discharged from the engine 1 to the intake system of the engine 1 as low-pressure EGR gas or high-pressure EGR gas as in the present embodiment is provided. Exhaust gas is included in the gas leaking into the engine room 2. In this way, exhaust gas may leak not only from the exhaust system but also from the intake system.

  Since exhaust gas contains components to be purified such as PM and NOx, if the exhaust gas leaks, the environment will be adversely affected. For this reason, it is desirable to detect and deal with exhaust gas leaks at an early stage.

  Therefore, in this embodiment, when the oxygen concentration of the gas in the engine room 2 detected by the outer detection unit 11b of the oxygen concentration detection sensor 11 is equal to or lower than the first predetermined concentration, gas leakage has occurred from the intake system or the exhaust system. I decided to judge.

  Here, the first predetermined concentration is an oxygen concentration that cannot be in the normal atmosphere if the oxygen concentration is lower than that, and is an oxygen concentration generated by mixing the exhaust gas from the intake system or the exhaust system with the gas in the engine room 2. .

  According to this embodiment, it is possible to uniformly determine that a gas leak including exhaust from the intake system or the exhaust system has occurred, and to detect gas leak including exhaust from the intake system or the exhaust system at an early stage. Therefore, it is possible to cope with gas leaks at an early stage, and it is possible to suppress exhaust gas from leaking and adversely affecting the environment.

Further, in this embodiment, when it is determined that gas leakage has occurred from the intake system or the exhaust system as described above, the reflux of the low pressure EGR gas and the high pressure EGR gas using the low pressure EGR device 30 and the high pressure EGR device 40 is stopped. . Then, when the oxygen concentration of the gas in the engine room 2 detected by the outer detection portion 11b of the oxygen concentration detection sensor 11 after the elapse of a predetermined time after stopping the recirculation of both EGR gases is equal to or higher than the second predetermined concentration, the intake air Judge that gas leaked from the system. On the other hand, if the oxygen concentration of the gas in the engine room 2 detected by the outer detection unit 11b of the oxygen concentration detection sensor 11 after a predetermined time has elapsed is lower than the second predetermined concentration, it is determined that a gas leak has occurred from the exhaust system. To do.

  Here, when the predetermined time is after the passage of time, when the intake air containing the low pressure EGR gas and the high pressure EGR gas leaks, the recirculation of the low pressure EGR gas and the high pressure EGR gas is stopped. This is the time during which the oxygen concentration of the gas in the room 2 changes so as to approach the oxygen concentration in the atmosphere.

  In addition, when the oxygen concentration is higher than the second predetermined concentration, when the intake air containing the low pressure EGR gas and the high pressure EGR gas leaks, the recirculation of the low pressure EGR gas and the high pressure EGR gas is stopped. The oxygen concentration of the gas in the engine room 2 changes so as to approach the oxygen concentration of the atmosphere and indicates that gas leakage has occurred from the intake system. If the oxygen concentration is lower than that, the low pressure EGR gas And even if the reflux of the high-pressure EGR gas is stopped, the oxygen concentration of the gas in the engine room 2 does not approach the oxygen concentration in the atmosphere, and the exhaust continues to leak, indicating that the gas leaked from the exhaust system. .

  According to the present embodiment, it is possible to detect at an early stage whether the gas leakage includes exhaust from either the intake system or the exhaust system. Here, the intake system as a portion where gas leakage including exhaust occurs includes a low pressure EGR passage 31 on the intake system side with respect to the low pressure EGR valve 32 and a high pressure EGR passage 41 on the intake system side with respect to the high pressure EGR valve 42, On the other hand, the exhaust system as a portion where gas leakage including exhaust occurs includes a low pressure EGR passage 31 on the exhaust system side with respect to the low pressure EGR valve 32 and a high pressure EGR passage 41 on the exhaust system side with respect to the high pressure EGR valve 42.

  In addition, in this embodiment, when it is determined that gas leakage has occurred from the intake system, the low-pressure EGR gas using the low-pressure EGR device 30 is stopped and the high-pressure EGR gas is returned using the high-pressure EGR device 40. Stop.

  According to this embodiment, since the low pressure EGR gas and the high pressure EGR gas are not recirculated, exhaust gas is not included in the intake air. Therefore, the exhaust leakage from the intake system is eliminated despite the occurrence of gas leakage from the intake system, and the engine can be continuously operated.

  Next, the gas leak detection control routine according to this embodiment will be described. FIG. 3 is a flowchart showing a gas leak detection control routine according to this embodiment. This routine is repeatedly executed every predetermined time.

  In step S101, the ECU 12 detects the driving state from the output values of various sensors.

  In step S102, the ECU 12 determines whether or not a gas leak detection condition is satisfied. Specifically, from the output values of the various sensors read in step S101, for example, the oxygen concentration detection sensor 11 is used for exhaust air-fuel ratio control, or the outer detection unit 11b of the oxygen concentration detection sensor 11 is the inner detection unit. It is confirmed whether or not the gas leak detection condition is satisfied when the oxygen concentration detection sensor 11 is not used for the above-described application, by checking whether or not it is used for the application such as being used for zeroing of 11a. to decide.

  When it is determined negative in step S102 that the gas leak detection condition is not satisfied, this routine is temporarily ended. If an affirmative determination is made in step S102 that the gas leak detection condition is satisfied, the process proceeds to step S103.

In step S <b> 103, the ECU 12 detects the oxygen concentration of the gas in the engine room 2 from the outside detection unit 11 b of the oxygen concentration detection sensor 11.

  In step S104, the ECU 12 determines whether or not the oxygen concentration of the gas in the engine room 2 detected in step S103 is equal to or lower than a first predetermined concentration. The first predetermined concentration is a value determined in advance by experiment, verification, or the like.

  If it is determined in step S104 that the oxygen concentration of the gas in the engine room 2 is higher than the first predetermined concentration, there is no gas leakage and the routine is temporarily terminated. If it is determined in step S104 that the oxygen concentration of the gas in the engine room is equal to or lower than the first predetermined concentration, it is determined that a gas leak has occurred from the intake system or the exhaust system, and the process proceeds to step S105.

  Determination means for determining that the gas leakage from the intake system or the exhaust system has occurred when the ECU 12 that executes step S104 of the present embodiment has an oxygen concentration of the gas in the engine room 2 of the present invention equal to or lower than the first predetermined concentration. It corresponds to.

  In step S <b> 105, the ECU 12 closes the low pressure EGR valve 32 and closes the high pressure EGR valve 42, stops recirculation of the low pressure EGR gas using the low pressure EGR device 30, and uses the high pressure EGR device 40. Stop gas reflux.

  When ECU12 which performs step S105 of a present Example judges that the gas leak has generate | occur | produced from the intake system or exhaust system of this invention, it corresponds to the judgment means which stops the recirculation | reflux of EGR gas using an EGR apparatus.

  In step S106, the ECU 12 waits for a predetermined time.

  The ECU 12 that executes step S106 of the present embodiment corresponds to determination means for causing a predetermined time to elapse after stopping the recirculation of the EGR gas of the present invention.

  In step S <b> 107, the ECU 12 detects the oxygen concentration of the gas in the engine room 2 from the outer side detection unit 11 b of the oxygen concentration detection sensor 11.

  In step S108, the ECU 12 determines whether or not the oxygen concentration of the gas in the engine room 2 detected in step S107 is equal to or higher than a second predetermined concentration. The second predetermined concentration is a value determined in advance by experiment, verification, or the like.

  If it is determined in step S108 that the oxygen concentration of the gas in the engine room 2 is equal to or higher than the second predetermined concentration, it is determined that a gas leak has occurred from the intake system, and the process proceeds to step S109. If it is determined in step S108 that the oxygen concentration of the gas in the engine room 2 is lower than the second predetermined concentration, it is determined that gas leakage has occurred from the exhaust system, and the process proceeds to step S110.

  The oxygen concentration of the gas in the engine room 2 detected by the oxygen concentration detection device after the elapse of a predetermined time after the ECU 12 executing the step S108 of the present embodiment stops the reflux of the EGR gas of the present invention is equal to or higher than the second predetermined concentration. If it is, it is determined that gas leakage has occurred from the intake system, and if it is lower than the second predetermined concentration, it corresponds to determination means for determining that gas leakage has occurred from the exhaust system.

In step S109, the ECU 12 notifies a gas leak from the intake system by turning on a warning lamp, for example, and thereafter closes the low-pressure EGR valve 32 and the high-pressure EGR valve 42, and the low-pressure EGR device 30 and The retreat travel for stopping the recirculation of the low pressure EGR gas and the high pressure EGR gas using the high pressure EGR device 40 and operating the engine 1 is performed.

  When ECU12 which performs step S109 of a present Example judges that the gas leak has generate | occur | produced from the intake system of this invention, it corresponds to the judgment means which stops the recirculation | reflux of EGR gas using an EGR apparatus.

  On the other hand, in step S110, the ECU 12 notifies a gas leak from the exhaust system, for example, by turning on a warning lamp. After that, the retreat traveling for operating the engine 1 may be performed so that the gas leakage from the exhaust system is reduced.

  According to this routine described above, by detecting the oxygen concentration of the gas in the engine room 2 using the outer side detection unit 11b of the existing oxygen concentration detection sensor 11, the intake system and the exhaust gas are increased without increasing the number of parts. It is possible to detect at an early stage whether the gas leak includes exhaust from the system. In particular, even when the operating state of the engine 1 hardly changes, for example, at a low rotation and low load, only the oxygen concentration of the gas in the engine room 2 is detected, so that gas leakage can be easily detected. In addition, when a gas leak is detected from the intake system, the low-pressure EGR gas and the high-pressure EGR gas can be stopped early by stopping the reflux of the high-pressure EGR gas and the high-pressure EGR gas.

<Example 2>
In this embodiment, as shown in FIG. 4, a separate oxygen concentration detection sensor 15 is disposed in the vicinity of the intercooler 8 in the engine room 2. In the present embodiment, the characteristic part will be described, and the other configuration is the same as that of the above embodiment, and the description thereof will be omitted.

  Corrosion occurs remarkably in the intercooler 8 made of an aluminum material arranged in the intake system, and therefore there is a high possibility that the intercooler 8 will cause intake gas leakage. For this reason, in this embodiment, the oxygen concentration detection sensor 15 for detecting the oxygen concentration of the gas in the engine room 2 is arranged in the vicinity of the intercooler 8 where gas leakage is likely to occur. According to the present embodiment, when a gas leak including exhaust from the intercooler 8 occurs, the oxygen concentration detection sensor 15 can detect a change in the oxygen concentration of the gas in the engine room 2 at an early stage. The oxygen concentration detection sensor 15 of the present embodiment corresponds to the oxygen concentration detection device of the present invention.

  The oxygen concentration detection sensor 15 may be disposed in the vicinity of the intake system in the engine room 2 other than the intercooler 8. According to this, when a gas leak including exhaust from the intake system occurs, the oxygen concentration detection sensor 15 can detect the change in the oxygen concentration of the gas in the engine room 2 at an early stage.

  Next, the gas leak detection control routine according to this embodiment will be described. FIG. 5 is a flowchart showing a gas leak detection control routine according to this embodiment. This routine is repeatedly executed every predetermined time.

  In this routine, since the oxygen concentration detection sensor 15 is disposed in the vicinity of the intercooler 8 exclusively for gas leak detection, the oxygen concentration detection sensor 15 is not used for other purposes. Therefore, steps S101 and S102 in the routine of FIG. 3 are not necessary. Since the subsequent processing of this routine starting from step S103 is the same processing as the routine of FIG. 3 in the first embodiment, the same reference numerals are given and description thereof is omitted.

  According to this routine described above, since the separate oxygen concentration detection sensor 15 is disposed in the vicinity of the intercooler 8, the oxygen concentration detection sensor 15 is used to appropriately detect the oxygen concentration of the gas in the engine room 2. be able to.

  The engine gas leak detection apparatus according to the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention.

1 is a diagram illustrating a schematic configuration of an engine and an intake system / exhaust system thereof according to Embodiment 1. FIG. 1 is a diagram illustrating a schematic configuration of an oxygen concentration detection sensor according to Embodiment 1. FIG. 3 is a flowchart illustrating a gas leak detection control routine according to the first embodiment. FIG. 4 is a diagram illustrating a schematic configuration of an engine and an intake system / exhaust system thereof according to a second embodiment. 9 is a flowchart illustrating a gas leak detection control routine according to the second embodiment.

Explanation of symbols

1 Engine 2 Engine Room 3 Intake Passage 4 Exhaust Passage 5 Turbocharger 5a Compressor 5b Turbine 6 First Throttle Valve 7 Air Flow Meter 8 Intercooler 9 Second Throttle Valve 10 Exhaust Purification Device 11 Oxygen Concentration Detection Sensor 11a Inside Detection Unit 11b Outside Detection Part 12 ECU
13 Crank position sensor 14 Accelerator position sensor 15 Oxygen concentration detection sensor 30 Low pressure EGR device 31 Low pressure EGR passage 32 Low pressure EGR valve 33 Low pressure EGR cooler 40 High pressure EGR device 41 High pressure EGR passage 42 High pressure EGR valve

Claims (6)

An engine located in the engine room;
An intake system and an exhaust system connected to the engine;
An exhaust supply means for supplying exhaust discharged from the engine to the intake system;
An oxygen concentration detection device arranged in the engine room for detecting the oxygen concentration of the gas in the engine room;
Determining means for determining that a gas leak has occurred from the intake system or the exhaust system based on the oxygen concentration of the gas in the engine room detected by the oxygen concentration detection device;
Equipped with a,
The exhaust gas supply means is an EGR device that takes a part of exhaust gas from the exhaust system as EGR gas and recirculates the EGR gas to the intake system.
The determination means determines that gas leakage has occurred from the intake system or the exhaust system when the oxygen concentration of the gas in the engine room detected by the oxygen concentration detection device is equal to or lower than a first predetermined concentration, When it is determined that a gas leak has occurred from the intake system or the exhaust system, the recirculation of the EGR gas using the EGR device is stopped, and the oxygen concentration detection device after a predetermined time has elapsed since the recirculation of the EGR gas was stopped. When the oxygen concentration of the gas in the engine room detected is equal to or higher than a second predetermined concentration, it is determined that a gas leak has occurred from the intake system, and when the oxygen concentration is lower than the second predetermined concentration, An engine gas leak detection device characterized in that it is determined that a gas leak has occurred from an exhaust system . A turbocharger having a turbine disposed in the exhaust system and a compressor disposed in the intake system;
The EGR device is a low-pressure EGR device that takes a part of exhaust gas as low-pressure EGR gas from the exhaust system downstream from the turbine and recirculates the low-pressure EGR gas to the intake system upstream from the compressor. The engine gas leak detection device according to claim 1 . 3. The engine gas leak detection device according to claim 1, wherein the oxygen concentration detection device is disposed in the vicinity of the intake system in the engine room. 4. An intercooler for cooling the intake air flowing through the intake system;
The engine oxygen leak detection device according to claim 3 , wherein the oxygen concentration detection device is disposed in the vicinity of the intercooler in the engine room. The oxygen concentration detection device includes an inner detection unit that detects an oxygen concentration of exhaust gas flowing through the exhaust system, and oxygen in the engine room that is outside the exhaust system for zeroing the inner detection unit gas leakage detection system for an engine according to any one of claims 1 to 4, characterized in that said is outside the detection portion of the detection device with an outer detector for detecting the concentration. The said determination means stops the recirculation | reflux of EGR gas using the said EGR apparatus, when it is judged that the gas leak has generate | occur | produced from the said intake system, The any one of Claims 1-5 characterized by the above-mentioned. The gas leak detection device for an engine as described.

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