JP5440799B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control apparatus including an intercooler for cooling intake air pressurized by a supercharger.

  An engine including a supercharger (such as a turbocharger) generally includes an intercooler in an intake passage for cooling the intake air pressurized by the supercharger. Some engines equipped with a supercharger include an exhaust gas recirculation (EGR) device that recirculates a part of exhaust gas to an intake passage and reburns it with fresh air.

  In the engine having such a configuration, when the intake air is cooled in the intercooler, moisture is condensed and condensed water is generated. If condensed water accumulates in the intercooler, the intercooler may corrode.

  The EGR gas supplied to the intake passage by the exhaust gas recirculation has a relatively high temperature and contains a relatively large amount of moisture as water vapor. Further, since the EGR gas contains sulfur components and the like, these components are also contained in the condensed water. For this reason, in the case of intake air including EGR gas, corrosion of the intercooler due to condensed water is likely to occur.

  In order to solve such problems, various proposals have been made to discharge condensed water to the outside of the intercooler at a predetermined timing. For example, there is an exhaust passage that connects an intercooler and an intake passage downstream of a second throttle (see, for example, Patent Document 1). When the engine (internal combustion engine) is idling, the pressure in the intake passage downstream of the second throttle is lower than the pressure in the intercooler. In the invention according to Patent Document 1, this pressure difference is used to discharge condensed water in the intercooler to the intake passage through the discharge passage when the engine is idle. Thereby, the corrosion of the intercooler by condensed water can be suppressed.

JP 2009-108761 A

  However, if a large amount of condensed water is discharged into the intake passage and flows into the combustion chamber at a stroke, the engine may be damaged due to the occurrence of a so-called water hammer phenomenon. For example, in the invention according to Patent Document 1, condensed water is discharged into the intake passage during idling of the internal combustion engine (when the accelerator is off), and the flow rate of the condensed water flowing into the intake passage is not controlled. Therefore, even in the invention according to Patent Document 1, the engine may be damaged by the condensed water. Further, if the condensate removal control is executed during engine idling, the engine speed is likely to fluctuate, and drivability may be deteriorated.

  The present invention has been made in view of such circumstances, and an engine capable of satisfactorily discharging condensed water from the intercooler into the intake passage while suppressing damage to the engine and deterioration of drivability due to the condensed water. An object of the present invention is to provide a control device.

  A first aspect of the present invention that solves the above problems includes an intercooler provided in an intake passage downstream of a supercharger that supercharges intake air of an engine of a vehicle, and an intake passage downstream of the intercooler. An intake adjustment valve provided on the intake side, and one end side is connected to an intake passage downstream of the intake adjustment valve and the other end side is connected to an intake passage upstream of the intake adjustment valve, and the condensation generated by the intercooler The condensed water is removed by adjusting a degree of opening of the condensed water removing passage through which water passes and the intake adjustment valve to generate a differential pressure between one end side and the other end side of the condensed water removing passage. Condensate removing means for executing condensate removal control for flowing out from the passage to the intake passage downstream of the intake adjustment valve, determination means for determining whether or not the engine is in an idle operation state, and the determination To the means Ri when said engine is determined to be idling, the control apparatus for an engine, characterized in that it comprises, and inhibiting means for inhibiting the execution of the condensate removal control by the condensate removal means.

  In the first aspect, it is possible to suppress a large amount of condensed water from being discharged from the intercooler to the intake passage, and it is possible to suppress damage to the engine due to the condensed water. In addition, since the fluctuation of the engine speed during idle operation (when the accelerator is off) is suppressed, the deterioration of drivability associated with the execution of the condensed water removal control is also suppressed.

  According to a second aspect of the present invention, the engine operating region includes a setting unit that is set according to an engine speed and a load, and the setting unit includes a load when the accelerator of the vehicle is fully opened. A full load line corresponding to the correlated parameters is set, and a region for prohibiting execution of the condensed water removal control is set within a predetermined range below the full load line, and the determination means includes: Based on the information of the setting unit, it is further determined whether or not the operating state of the engine is in a region in which execution of the condensed water removal control is prohibited, and the prohibiting unit determines whether the operating state of the engine is The engine control according to the first aspect, wherein execution of the condensed water removal control by the condensed water removing means is prohibited even when it is determined that the area is in a region where the execution of the condensed water removal control is prohibited. apparatus A.

  In the second aspect, since the execution of the condensed water removal control is prohibited within a predetermined range below the full load line, the occurrence of smoke can be suppressed. During execution of the condensed water removal control, the opening of the intake adjustment valve is adjusted to the closed side to generate a differential pressure. For this reason, when the condensate removal control is executed, the intake air amount is decreased and the air-fuel ratio is changed to the rich side, and smoke is easily generated accordingly. And especially in the predetermined range below the full load line where smoke is likely to occur, the generation of smoke can be significantly suppressed by prohibiting execution of the condensed water removal control. Examples of the “parameter correlated with the load” include vehicle torque, accelerator opening, fuel injection amount, intake air amount, and the like.

  In a third aspect of the present invention, the predetermined range is set such that an air-fuel ratio at the time of executing the condensed water removal control does not fall below an air-fuel ratio on the full load line during normal operation of the engine. There exists in the control apparatus of the engine of the 2nd aspect characterized by the above-mentioned.

  In the third aspect, by setting the predetermined range based on the air-fuel ratio, it is possible to appropriately set the range in which smoke is likely to occur as the condensed water removal control is executed as the predetermined range.

  The fourth aspect of the present invention further includes an EGR passage that connects the exhaust passage and the intake passage, and an EGR valve that adjusts the amount of EGR gas flowing from the EGR passage into the intake passage, The engine control device according to the second aspect, wherein the predetermined range is set to a range in which the EGR valve is closed and the flow of EGR gas from the EGR flow path to the intake passage is blocked. It is in.

  In the fourth aspect, adverse effects on the normal operation of the engine can be avoided. The operation region where both EGR flow paths are blocked is a region where it is difficult to ensure the intake amount necessary for engine operation when the condensed water removal control is executed. Therefore, by prohibiting the condensed water removal control in such a region, it is possible to avoid an adverse effect on the normal operation of the engine.

  According to a fifth aspect of the present invention, a sensor for detecting the intake state of the engine is provided in the intake passage upstream of the connection portion between the one end side of the condensed water removal passage and the intake passage. The engine control device according to any one of the first to fourth aspects is characterized by the above.

  In the fifth aspect, water adhesion, a decrease in sensitivity, and the like can be suppressed by the adhesion of water to the sensor for detecting the state of intake air. Examples of the sensor for detecting the intake air state include a linear air-fuel ratio sensor, a temperature sensor, and a humidity sensor. However, the sensor is not limited to this, and various sensors that can detect the intake air state are used. Sensors are included.

  According to a sixth aspect of the present invention, there is provided a detecting means for detecting the amount of the condensed water, and a request for requesting execution of the condensed water removal control when the condensed water exceeds a predetermined amount based on a detection result of the detecting means. The condensed water removal means executes the condensed water removal control when the request means requests execution of the condensed water removal control. It exists in the control apparatus of the engine of any one aspect.

  In the sixth aspect, the execution frequency of the condensed water removal control is appropriate.

  In the present invention, the condensed water removal control is performed at an appropriate timing according to the operating state of the engine. Therefore, the condensed water can be favorably discharged from the intercooler into the intake passage while suppressing the engine damage and the drivability deterioration due to the condensed water.

It is a figure showing a schematic structure of an engine system concerning one embodiment of the present invention. It is the schematic explaining arrangement | positioning of the condensed water removal pipe | tube which concerns on one Embodiment of this invention. It is a block diagram which shows schematic structure of the control apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of the map with which the setting part which concerns on one Embodiment of this invention is provided. It is a graph which shows the relationship between an engine load and intake air amount. It is a flowchart which shows an example of the condensed water removal control which concerns on one Embodiment of this invention. It is a graph which shows the relationship between an engine load and an exhaust air fuel ratio. It is a figure which shows an example of the map with which the setting part which concerns on one Embodiment of this invention is provided. It is a table | surface which shows the relationship between the driving | operation area | region of an engine, and the adjustment state of various valves. It is the schematic explaining the modification of arrangement | positioning of the condensed water removal pipe | tube which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, an engine system 10 according to the present embodiment includes an in-line four-cylinder diesel engine (hereinafter simply referred to as “engine”) 12 including four cylinders (combustion chambers) 11 arranged in series. . An intake manifold (intake passage) 13 is connected to an intake port (not shown) of each cylinder 11, and an intake pipe (intake passage) 14 is connected to the intake manifold 13. On the other hand, an exhaust manifold (not shown) of each cylinder 11 is connected to an exhaust manifold 15, and an exhaust pipe (exhaust passage) 16 is connected to the exhaust manifold 15.

  In addition, an injector (fuel injection valve) 17 for injecting fuel is provided corresponding to each cylinder 11, and each injector 17 is connected to a common rail 18. The common rail 18 is connected to a fuel tank via a supply pump (high pressure pump) (not shown). Fuel is pumped from the fuel tank by the supply pump, and high-pressure fuel in the common rail 18 is injected from the injector 17 into each cylinder 11.

  A turbocharger (supercharger) 19 is provided in the middle of the intake pipe 14 and the exhaust pipe 16. In the turbocharger 19, when exhaust gas flows from the engine 12, the turbine rotates by the flow of exhaust gas, and the compressor rotates as the turbine rotates, and air is sucked into the turbocharger 19 from the intake pipe 14 and pressurized. It has come to be.

  The intake pipe 14 upstream of the turbocharger 19 is provided with an air cleaner 20 and a first throttle valve 21 that is a low-pressure intake adjustment valve. The air cleaner 20 is provided with a humidity sensor 22 that detects the humidity of the intake air. The first throttle valve 21 adjusts the amount of fresh air that has passed through the air cleaner 20 (fresh air amount), and by this adjustment, the amount of exhaust gas introduced into the intake pipe 14 via the low-pressure EGR pipe (described later) ( The low-pressure EGR gas amount) is indirectly adjusted. An air flow sensor 23 for detecting the intake air flow rate is provided on the downstream side of the air cleaner 20. In this embodiment, the air flow sensor 23 has a temperature detection function, and detects the intake air temperature together with the intake air flow rate.

  An intercooler 24 that cools the intake air whose temperature has risen due to pressurization by the turbocharger 19 is disposed in the intake pipe 14 downstream of the turbocharger 19. The intercooler 24 forms an intake passage together with the intake pipe 14. The intake pipe 14 on the downstream side of the intercooler 24 is provided with a second throttle valve 26 that is an intake adjustment valve that opens and closes the intake pipe 14 by driving an electric actuator.

  The second throttle valve 26 adjusts the amount of intake air that has passed through the intercooler 24 (fresh air amount + low pressure EGR gas amount), and exhaust gas introduced into the intake pipe 14 via the EGR pipe described later by this adjustment. The amount (EGR gas amount) is adjusted indirectly.

  One end of an EGR pipe (EGR flow path) 27 through which high-pressure exhaust gas (EGR gas) circulates is connected to the intake pipe 14 downstream of the second throttle valve 26. The other end of the EGR pipe 27 is connected to the upstream side of the turbocharger 19 of the exhaust pipe 16. An EGR cooler 28 is provided in the EGR pipe 27, and an EGR valve 29 is provided in a connection portion of the EGR pipe 27 with the intake pipe 14. When the EGR valve 29 is opened, a part of the high-pressure exhaust gas flowing upstream from the turbocharger 19 of the exhaust pipe 16 flows into the EGR pipe 27 and is cooled by the EGR cooler 28, and then is introduced into the intake pipe 14. It comes to be supplied. The EGR valve 29 may be provided so that the amount of EGR gas flowing from the EGR pipe 27 into the intake pipe 14 can be adjusted.

A linear air-fuel ratio sensor 30 that is an air-fuel ratio detecting means for detecting the air-fuel ratio of the intake air is provided downstream of the EGR pipe 27 of the intake pipe 14. The intake manifold 13 is provided with a boost pressure sensor 31 that is a pressure detection means for detecting the pressure inside the intake manifold 13. The air-fuel ratio detecting means may be any means that can detect the air-fuel ratio of the intake air, and may be, for example, an oxygen (O ₂ ) sensor in addition to the linear air-fuel ratio sensor.

  Further, on the downstream side of the turbocharger 19 of the exhaust pipe 16, a diesel oxidation catalyst 32 that is an exhaust purification catalyst and a diesel particulate filter (DPF: Diesel Particulate Filter: hereinafter “DPF”) 33) are arranged in order from the upstream side.

  One end of a low pressure EGR pipe (low pressure EGR flow path) 34 in which a part of low pressure exhaust gas (low pressure EGR gas) circulates downstream of the turbocharger 19 of the exhaust pipe 16 and downstream of the DPF 33 in this embodiment. Is connected. The other end of the low pressure EGR pipe 34 is connected to the intake pipe 14 between the turbocharger 19 and the throttle valve 21. As in the case of the EGR pipe 27, the low-pressure EGR pipe 34 is provided with a low-pressure EGR cooler 35 and a low-pressure EGR valve 36. When the low pressure EGR valve 36 is opened, the low pressure EGR gas flowing downstream of the turbocharger 19 in the exhaust pipe 16 is cooled by the low pressure EGR cooler 35 and supplied to the intake pipe 14. Yes. The “EGR flow path” recited in the claims includes an EGR pipe (EGR flow path) 27 and a low pressure EGR pipe (low pressure EGR flow path) 34, and the “EGR valve” includes an EGR valve 29 and A low pressure EGR valve 36 is included.

  Further, differential pressure sensors 37 as differential pressure detection means are provided at both ends of the low pressure EGR pipe 34. The differential pressure sensor 37 detects the differential pressure between the pressure upstream of the turbocharger 19 in the intake pipe 14 and the pressure downstream of the turbocharger 19 in the exhaust pipe 16. That is, the flow rate and flow rate of the low pressure EGR gas flowing through the low pressure EGR pipe 34 are obtained from the detection result of the differential pressure sensor 37.

  By the way, in the engine system 10 having such a configuration, when the intake air is cooled in the intercooler 24, moisture is condensed and condensed water is generated. The generated condensed water accumulates in the intercooler 24 or in the intake pipe 14 near the intercooler 24, and may cause a problem that the intercooler 24 and the intake pipe 14 are corroded. For this reason, it is necessary to appropriately discharge the condensed water accumulated in the intercooler 24 or the like. In the present invention, the condensed water accumulated in the intercooler 24 and the like is discharged through the condensed water removing pipe (condensed water removing passage) 38. One end side of the condensed water removal pipe 38 is connected to the intake passage on the downstream side of the second throttle valve 26, in this embodiment, the intake manifold 13. That is, a sensor for detecting the intake state of the engine 12, such as the linear air-fuel ratio sensor 30, is connected to the intake pipe 14 upstream of the connection portion between the one end side of the condensed water removal pipe 38 and the intake manifold 13. Is provided. For this reason, when the condensed water flows out from the condensed water removing pipe 38, it is possible to prevent the occurrence of water cracking due to the condensed water of the linear air-fuel ratio sensor 30 or the like.

  The other end side of the condensed water removal pipe 38 is connected to the intake passage upstream of the second throttle valve 26, in this embodiment, the intercooler 24. Here, as shown in FIG. 2, the intercooler 24 is arranged so that the direction of intake air flow is substantially horizontal (left and right in the figure) in the present embodiment. The intercooler 24 has a height h1 from the road surface of the inlet 24a and a height h1 from the road surface of the inlet 24a and the outlet 24b so that the height h2 from the road surface of the outlet 24b is substantially the same. The h2 is provided so as to be higher than the height h3 from the road surface of the bottom surface portion 24c of the intercooler 24. In such a configuration, the condensed water generated by the intercooler 24 tends to accumulate inside the intercooler 24, particularly in the vicinity of the outlet 24b. For this reason, in this embodiment, the other end side of the condensed water removal pipe 38 is connected to the intercooler 24. Further, near the outlet 24b of the intercooler 24, as shown in FIG. 1, a liquid level sensor 39, which is a detecting means for detecting the amount of condensed water accumulated in the intercooler 24, is provided.

  The control device of the engine 12 performs the condensed water removal control at a predetermined timing, thereby causing the condensed water accumulated in the intercooler 24 to flow out from the condensed water removal pipe 38 to the intake manifold 13.

Hereinafter, the condensed water removal control by the control device of the engine 12 will be described in detail.
The control device of the engine 12 is configured by an ECU (electronic control unit) 40 and various sensors. The ECU 40 includes an input / output device, a storage device (ROM, RAM, etc.), a central processing unit (CPU), a timer counter, and the like, and performs overall control of the engine 12 based on signals from the various sensors. On the input side of the ECU 40, various sensors such as a crank angle sensor for detecting the crank angle of the engine 12 in addition to the air flow sensor 23, the linear air-fuel ratio sensor 30, the boost pressure sensor 31, the humidity sensor 22, and the differential pressure sensor 37 described above. Are connected, and detection information from these sensors is input. On the other hand, various output devices such as the injector 17, the first and second throttle valves 21 and 26, the EGR valve 29, and the low pressure EGR valve 36 are connected to the output side of the ECU 40. These various output devices output various information such as the fuel injection amount and valve opening calculated by the ECU 40 based on the detection information detected by the various sensors as described above.

  As shown in FIG. 3, the ECU 40 includes a condensed water removing unit 41, a request unit 42, a determination unit 43, a prohibition unit 44, and a setting unit 45.

  The condensed water removing means 41 adjusts the opening degree of the second throttle valve 26 to generate a differential pressure between one end side and the other end side of the condensed water removing pipe 38, thereby condensing the condensed water to the condensed water removing pipe 38. From the second throttle valve 26, the condensed water removal control is performed at a predetermined timing so as to flow out into the intake passage downstream of the second throttle valve 26. In the present embodiment, the condensed water removing means 41 generates a differential pressure between the intake manifold 13 and the intercooler 24 by adjusting the second throttle valve 26 in the closing direction, whereby the condensed water is removed from the condensed water removing pipe. 38 to the intake manifold 13.

  The request means 42 requests the condensed water removal means 41 to execute the condensed water removal control when the condensed water exceeds a predetermined amount based on the detection result of the liquid level sensor 39 which is the condensed water amount detection means. In the present embodiment, the condensed water removing unit 41 executes the condensed water removing control when there is a request from the request unit 42.

  The determination unit 43 determines whether or not the operating state of the engine 12 is in a region where execution of the condensed water removal control is prohibited based on signals from various sensors included in the engine 12.

  The prohibition unit 44 prohibits the execution of the condensed water removal control by the condensed water removal unit 41 when the determination unit 43 determines that the operation state of the engine 12 is in a region where the execution of the condensed water removal control is prohibited. The prohibition instruction by the prohibiting unit 44 has priority over the request from the requesting unit 42. Therefore, even when the condensed water removal control is being executed, if the prohibited means 44 prohibits the execution of the condensed water removal control, the condensed water removal means 41 stops the execution of the condensed water removal control.

  Here, the determination of whether or not the operation state of the engine 12 by the determination unit 43 is in a region where the execution of the condensed water removal control is prohibited will be further described.

  Specifically, the determination unit 43 first determines whether or not the operating state of the engine 12 is an idle operation. As will be described later, when the operating state of the engine 12 is an idle operation, the execution of the condensed water removal control is prohibited. Therefore, when the determination unit 43 determines that the operating state of the engine 12 is in idle operation, the prohibition unit 44 prohibits the execution of the condensed water removal control by the condensed water removal unit 41.

  Here, whether or not the engine 12 is in the idle operation state is determined, for example, depending on whether or not the current engine speed is lower than a predetermined speed (for example, about 1000 [rpm]). The predetermined number of revolutions can be variably set according to the state of the vehicle (for example, whether or not the electric load is high when using an air conditioner or the like).

  Further, the determination unit 43 determines whether or not the operating state of the engine 12 is in a region where the execution of the condensed water removal control is prohibited based on the information of the setting unit 45.

  In the setting unit 45, the operation region of the engine 12 is set according to the engine speed and the load. That is, the setting unit 45 includes, for example, a map in which the operation region of the engine 12 is set according to the engine speed and load (see FIG. 4). In the map of the setting unit 45, a full load line corresponding to a parameter correlated with a load when the accelerator of the vehicle is fully opened is set. For example, the full load line L 1 corresponding to the intake air amount is set in the map of the setting unit 45. In the map of the setting unit 45, a deceleration load line L2 corresponding to the intake air amount when the accelerator of the vehicle is fully closed (accelerator off) is set.

  Further, in the map of the setting unit 45, an operation region A in which execution of the condensed water removal control is prohibited is set in a predetermined range below the full load line L1. That is, a prohibition line (shown by a dotted line in the figure) L3 is set below the full load line L1 at predetermined intervals, and this prohibition line L3 is an operation in which execution of the condensed water removal control is prohibited when the accelerator is on. This is a boundary between the region A and the operation region B in which execution of the condensed water removal control is permitted.

  Here, the prohibition line L3 is set based on, for example, the relationship between the load of the engine 12 and the intake air amount when a predetermined engine speed is set. FIG. 5 is a graph showing the relationship between the load of the engine 12 and the intake air amount at a predetermined engine speed Ne1 (see FIG. 4). As shown in FIG. 5, the intake air amount during normal operation always exceeds the minimum air amount necessary for operation of the engine 12 (thick line in FIG. 5). However, when the condensed water removal control is executed, the second throttle valve 26 is adjusted in the closing direction, so that the intake air amount when the condensed water removal control is executed is lower than the intake air amount during normal operation. For this reason, when the load of the engine 12 exceeds the predetermined value T1, the intake air amount when the condensed water removal control is executed is less than the minimum air amount necessary for the operation of the engine 12. That is, if the condensed water removal control is executed in a state where the load of the engine 12 exceeds the predetermined value T1, the minimum air amount necessary for the operation of the engine 12 cannot be obtained.

  The prohibition line L3 is set based on such a result. That is, the forbidden line L3 defines the limit value of the load that can secure the minimum amount of air necessary for the operation of the engine 12 as the amount of intake air when the condensed water removal control is executed.

  In the present invention, as described above, the condensed water removal control is executed only when the operation state of the engine 12 is in the region (operation region B) where the execution of the condensed water removal control is permitted. For example, when the operation state of the engine 12 is in the idle operation region or when a high load is required, that is, when the operation state of the engine 12 is in the operation region A, the condensed water removal control is executed. There is nothing.

  Thereby, it is possible to secure a load necessary for traveling of the vehicle while discharging the condensed water in the intercooler 24 satisfactorily. Further, by executing the condensed water removal control only when the operating state of the engine 12 is in the operation region B, it is possible to appropriately control the outflow amount of the condensed water. Therefore, it is possible to suppress a large amount of condensed water from the intercooler 24 from being discharged to the intake manifold (intake passage) 13, and it is also possible to suppress damage to the engine 12 due to the condensed water.

  Further, since the execution of the condensed water removal control is prohibited in the idling region A, fluctuations in the engine speed during the idling operation are suppressed. Therefore, the deterioration of drivability accompanying the execution of the condensed water removal control is also suppressed. Furthermore, since the execution of the condensed water removal control is prohibited in the operation region A below the full load line, it is also possible to suppress an increase in smoke due to excessive fuel (air lean).

  Hereinafter, an example of the condensed water removal control according to the present embodiment will be described with reference to the flowchart of FIG.

  As shown in FIG. 6, first, it is detected by the liquid level sensor 39 that a predetermined amount or more of condensed water has accumulated in the intercooler 24, and the request means 42 performs the condensed water removal control on the condensed water removal means 41. When execution is requested (step S1: YES), the process proceeds to step S2, and the determination unit 43 determines whether or not the operation state of the engine 12 is an idle operation state. That is, in step S2, it is determined whether or not the current engine speed is below a predetermined speed (about 1000 [rpm] in one example). If the operation state of the engine 12 is not idle operation (step S2: NO), the process proceeds to step S3.

  When there is no request for execution of the condensed water removal control by the request means 42 (step S1: NO), when the operating state of the engine 12 is in the idle operation region (step S2: YES), the condensed water removal control is performed. The normal operation control of the engine 12 is executed without being executed (step S7).

  In step S <b> 3, the determination unit 43 further determines whether or not the operating state of the engine 12 is in a region where the execution of the condensed water removal control is prohibited. In the present embodiment, as described above, in the map of the setting unit 45 (see FIG. 4), the operation state of the engine 12 is in the operation region A between the full load line L1 and the prohibition line L3, or from the prohibition line L3. Is also in the lower operation region B. Here, when the operation state of the engine 12 is in the operation region B (step S3: YES), the process proceeds to step S4, and the condensed water removal control is executed by the condensed water removing means 41. On the other hand, when the operation state of the engine 12 is in the operation region A (step S3: NO), the normal operation control of the engine 12 is executed without executing the condensed water removal control (step S7).

  When the condensed water removal control is executed in step S4, it is then determined in step S5 whether the condensed water removal is completed. Specifically, it is determined whether or not the condensed water in the intercooler 24 is less than a predetermined amount. This determination is performed based on the detection result of the liquid level sensor 39, for example. Here, when the amount of the condensed water is not less than the predetermined amount, that is, when the removal of the condensed water is not completed (step S5: NO), the process returns to step S2.

  In step S2, it is determined again whether or not the operating state of the engine 12 is in the idling region. When the operation state of the engine 12 is not in the idle operation region (step S2: NO), the process proceeds to step S3. On the other hand, when the operation state of the engine 12 is in the idle operation region, the condensed water removal control is stopped and the normal operation control of the engine 12 is executed (step S7).

  In step S3, it is determined again whether or not the operating state of the engine 12 is in a region where the execution of the condensed water removal control is prohibited. When the operation state of the engine 12 is in a region where the execution of the condensed water removal control is permitted (operation region B), the process proceeds to step S4, and the condensed water removal control is continued. On the other hand, when the operation state of the engine 12 is in a region (operation region A) where the execution of the condensed water removal control is prohibited, the condensed water removal control is stopped and the normal operation control of the engine 12 is executed (step). S7).

  Thereafter, when it is determined in step S5 that the condensed water has been removed, that is, the condensed water in the intercooler 24 has become less than a predetermined amount (step S5: YES), the process proceeds to step S6, and the condensed water removal request is reset. Then, normal operation control of the engine 12 is executed (step S7). Thereby, a series of condensed water removal control is complete | finished.

  In the present embodiment, an example in which the map of the setting unit 45 is set according to the intake air amount determined by the engine speed and the load is described. However, the map of the setting unit 45 is the engine speed and the load. May be set based on other parameters determined by the above, for example, an air-fuel ratio (exhaust A / F). When the map of the setting unit 45 is set based on the air-fuel ratio, the air-fuel ratio when executing the condensed water removal control is the air-fuel ratio on the entire load line during the normal operation of the engine 12 (the lowest value of the air-fuel ratio). It is preferable that the forbidden line L3 is set so as not to fall below.

  FIG. 7 is a graph showing the relationship between the load of the engine 12 and the exhaust A / F at a predetermined engine speed Ne1 (see FIG. 4). As shown in FIG. 7, both the exhaust A / F during normal operation and the exhaust A / F during execution of the condensed water removal control tend to gradually decrease as the load on the engine 12 increases. However, when the condensed water removal control is executed, the second throttle valve 26 is adjusted in the closing direction, so that the exhaust A / F during execution of the condensed water removal control is lower than the exhaust A / F during normal operation. Become. For this reason, when the load of the engine 12 exceeds the predetermined value T1, the exhaust A / F during execution of the condensed water removal control falls below the lowest value (value at full load) E1 of the exhaust A / F during normal operation. End up. If the exhaust A / F is below the minimum value E1, smoke may increase significantly due to excessive fuel. Therefore, when the map of the setting unit 45 is set based on the exhaust A / F determined by the engine speed and the load, the air-fuel ratio at the time of executing the condensed water removal control as described above is the normal operation. It is preferable that the prohibition line L3 is set so as not to fall below the air-fuel ratio E1 on the entire load line at that time. Thereby, the condensed water in the intercooler 24 can be removed while suppressing an increase in smoke due to excessive fuel.

  In the above-described embodiment, when the condensed water removal control is executed, the opening degree of the second throttle valve 26 is adjusted so that a differential pressure is generated between one end side and the other end side of the condensed water removal pipe 38. However, at this time, when EGR gas or low-pressure EGR gas is used, the first throttle valve 21, the EGR valve 29, and the low-pressure EGR valve 36 are appropriately adjusted together with the second throttle valve 26. You may do it. As a result, the air-fuel ratio can be adjusted to a more appropriate value, and drivability can be improved.

  For example, as shown in FIG. 8, the usage state of the EGR gas and the low pressure EGR gas is determined according to the operation region of the engine 12. In the example of FIG. 8, only EGR gas is used in the operation region C which is a low load region, and EGR gas and low pressure EGR gas are used in combination in the operation region D where the load is higher than that in the operation region C. Furthermore, only the low pressure EGR gas is used in the operation region E where the load is higher than that in the operation region D, and the EGR gas and the low pressure EGR gas are not used in the operation region F which is the highest load region. During normal operation, for example, as shown in the table of FIG. 9A, the first and second throttle valves 21, 26, the EGR valve 29, and the low-pressure EGR valve 36 are in accordance with each of these operation regions. Each opening degree is adjusted appropriately. Further, at the time of executing the condensed water removal control, for example, as shown in the table of FIG. 9B, the opening degrees of the first and second throttle valves 21, 26, the EGR valve 29, and the low pressure EGR valve 36 are set. Adjust as appropriate. For example, in the operation region C in which EGR gas is used, the air-fuel ratio can be adjusted to the lean side by adjusting the EGR valve 29 in the closing direction, and the air-fuel ratio can be adjusted by opening the EGR valve 29 in the opening direction. The fuel ratio can be adjusted to the rich side. By appropriately adjusting the air-fuel ratio in this way, it is possible to further improve the drivability during execution of the condensed water removal control.

  In addition, when the opening degree of each of the first throttle valve 21, the EGR valve 29, and the low pressure EGR valve 36 is adjusted together with the second throttle valve 26 in this way, the EGR gas and the low pressure EGR gas are not used. It is preferable to set the operation region F to a region in which execution of the condensed water removal control is prohibited. Thereby, the drivability at the time of execution of condensed water removal control can be improved more reliably.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. The present invention can be modified as appropriate without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the configuration in which the intercooler 24 is arranged so that the direction in which the intake air flows is substantially horizontal (see FIG. 2), but the structure of the intake passage including the intercooler 24 is particularly limited. Is not to be done. For example, as shown in FIG. 10A, the height h1 from the road surface of the inlet 24a of the intercooler 24 is higher than the height h3 from the road surface of the bottom surface portion 24c of the intercooler 24, and from the road surface of the outlet 24b. The height h <b> 2 may be lower than the height h <b> 3 from the road surface of the bottom surface portion 24 c of the intercooler 24. In such a configuration, the condensed water generated by the intercooler 24 is likely to accumulate in the intake pipe 14 near the outlet 24 b of the intercooler 24. Therefore, in this example, it is preferable that the other end side of the condensed water removal pipe 38 is connected to the intake pipe 14 on the downstream side of the intercooler 24.

  Further, for example, as shown in FIG. 10B, the intercooler 24 may be arranged so that the direction in which the intake air flows is substantially vertical (up and down in the figure). In such a configuration, the condensed water generated by the intercooler 24 is likely to be accumulated in the intake pipe 14 near the inlet 24 a of the intercooler 24. Therefore, in the case of this example, it is preferable that the other end side of the condensed water removal pipe 38 is connected to the intake pipe 14 upstream of the intercooler 24.

  Of course, even with these configurations, the condensed water generated by the intercooler 24 can be satisfactorily discharged to the intake manifold 13 via the condensed water removal pipe 38.

  For example, in the above-described embodiment, the amount of condensed water accumulated in the intercooler 24 is detected by the liquid level sensor 39, but is not limited to direct sensing by the liquid level sensor 39, The amount of condensed water generated may be obtained by estimation or the like. For example, the liquid level sensor 39 may be replaced with a temperature sensor, and the amount of condensed water generation may be obtained by estimation based on the detection result of the temperature sensor. In this case, the amount of water vapor in the intake air is calculated from the information of the air flow sensor 23 and the humidity sensor 22, and the saturated water vapor amount of the gas passing through the outlet of the intercooler 24 is calculated from the information of the temperature sensor and the boost pressure sensor 31. The amount of water vapor in the 24 outlet passage gas exceeds the amount of saturated water vapor is estimated as the amount of condensed water generated (condensed water generation amount).

  Alternatively, when EGR gas and low-pressure EGR gas are used, the amount of low-pressure EGR gas is calculated using information from the differential pressure sensor 37, and the amount of water vapor in the low-pressure EGR gas is calculated from the combustion gas component ratio. Thus, the amount of water vapor in the intercooler 24 outlet passage gas (intake air + EGR gas) is calculated, and the amount of condensed water generated can be estimated based on the result.

  Further, for example, in the above-described embodiment, the engine control device includes a detection unit that detects the amount of condensed water accumulated in the intercooler, and requests execution of the condensed water removal control based on the detection result of the detection unit. Although the configuration provided with the requesting means to explain has been described, these detection means and requesting means do not necessarily have to be provided. In that case, for example, the condensate removal control may be executed every time a certain period elapses regardless of the amount of the condensate.

  Further, in the above-described embodiment, the determination unit determines whether or not the engine is in the idling operation state, and the operation state of the engine is in a region where the execution of the condensed water removal control is prohibited based on the information of the setting unit. Whether or not to further determine. However, the determination means may be any means that determines at least whether or not the engine is in the idling operation state.

DESCRIPTION OF SYMBOLS 10 Engine system 11 Cylinder 12 Engine 13 Intake manifold 14 Intake pipe 15 Exhaust manifold 16 Exhaust pipe 17 Injector 18 Common rail 19 Turbocharger 20 Air cleaner 21 First throttle valve 22 Humidity sensor 23 Air flow sensor 24 Intercooler 26 Second throttle valve 27 EGR pipe 28 EGR cooler 29 EGR valve 30 Linear air-fuel ratio sensor 31 Boost pressure sensor 34 Low pressure EGR pipe 35 Low pressure EGR cooler 36 Low pressure EGR valve 37 Differential pressure sensor 38 Condensate removal pipe 39 Liquid level sensor 41 Condensate removal means 42 request means 43 determination means 44 prohibition means 45 setting unit

Claims (6)

An intercooler provided in an intake passage downstream of a supercharger for supercharging intake air of a vehicle engine;
An intake adjustment valve provided in an intake passage downstream of the intercooler;
One end side is connected to an intake passage downstream from the intake adjustment valve, and the other end is connected to an intake passage upstream from the intake adjustment valve to allow condensed water removal passage to pass the condensed water generated by the intercooler. When,
By adjusting the opening of the intake adjustment valve to generate a differential pressure between one end side and the other end side of the condensed water removal passage, the condensed water is downstream from the intake water adjustment valve from the condensed water removal passage. Condensed water removal means for performing condensed water removal control to flow out into the intake passage of
Determination means for determining whether or not the engine is in an idle operation state;
A prohibiting means for prohibiting execution of the condensed water removal control by the condensed water removing means when the judging means determines that the engine is in an idle operation state;
An engine control device comprising: The engine operating region comprises a setting unit set according to the engine speed and load,
In the setting unit, a full load line corresponding to a parameter correlated with a load when the accelerator of the vehicle is fully opened is set, and the condensed water removal is within a predetermined range below the full load line. An area that prohibits execution of control is set,
The determination means further determines whether or not the operating state of the engine is in a region where the execution of the condensed water removal control is prohibited based on the information of the setting unit,
The prohibiting means executes the condensed water removal control by the condensed water removing means even when it is determined by the determining means that the operating state of the engine is in a region where the execution of the condensed water removal control is prohibited. The engine control device according to claim 1, wherein the engine control device is prohibited.   The predetermined range is set to a range in which an air-fuel ratio at the time of executing the condensed water removal control does not fall below an air-fuel ratio on the full load line during normal operation of the engine. The engine control apparatus according to 2. An EGR flow path connecting the exhaust passage and the intake passage;
An EGR valve that adjusts the amount of EGR gas flowing from the EGR flow path into the intake passage;
Further comprising
The engine control according to claim 2, wherein the predetermined range is set to a range in which the EGR valve is closed and the flow of EGR gas from the EGR flow path to the intake passage is blocked. apparatus.   The sensor for detecting the state of intake air of the engine is provided in the intake passage upstream of a connection portion between the one end side of the condensed water removal passage and the intake passage. Item 5. The engine control device according to any one of Items 1 to 4. Detection means for detecting the amount of the condensed water;
Request means for requesting execution of the condensed water removal control when the condensed water exceeds a predetermined amount based on the detection result of the detecting means;
Further comprising
The said condensed water removal means performs the said condensed water removal control, when there exists a request | requirement of execution of the said condensed water removal control by the said request | requirement means. The engine control device described.