JP2016031063A - Exhaust gas recirculation device of engine with turbocharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discharge condensate water generated from EGR gas leaking to a downstream side of an EGR valve when the EGR valve is fully closed to outside before an engine is started.SOLUTION: In a low-pressure loop EGR device of an engine 1 mounted in a vehicle and including a turbocharger 7, an inlet 17b of an EGR passage 17 is connected to an exhaust passage 5 downstream of a turbine 9 and an outlet 17a thereof is connected to an intake passage 3 upstream of a compressor 8. An EGR valve 18 is provided in the EGR passage 17. The outlet 17a of the EGR passage 17 is disposed at a higher position than the inlet 17b in a perpendicular direction, so that condensate water can flow down from a downstream side to an upstream side of the EGR valve 18 and so that the condensate water can flow down the EGR passage 17 to the exhaust passage 5. An electronic control unit (ECU) 50 forcibly opens the EGR valve 18 in a fully closed state when a door sensor 58 detects that a driver door is opened in order to discharge the condensate water from the downstream side to the upstream side of the EGR valve 18 when the engine 1 is stopped.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine equipped with a supercharger, and relates to an exhaust gas recirculation device for an engine with a supercharger that causes a part of the exhaust of the engine to flow as an exhaust recirculation gas to an intake passage and recirculate to the engine.

  2. Description of the Related Art Conventionally, for example, an exhaust gas recirculation (EGR) device for an automobile engine uses a part of exhaust gas after combustion discharged from a combustion chamber of the engine to an exhaust passage as EGR gas to be taken in through the EGR passage. It is led to the passage, mixed with the intake air flowing through the intake passage, and recirculated to the combustion chamber. EGR gas flowing through the EGR passage is adjusted by an EGR valve provided in the EGR passage. By this EGR, nitrogen oxide (NOx) in the exhaust gas can be mainly reduced, and fuel efficiency can be improved at the time of partial load of the engine.

  By the way, it is well known that an engine equipped with a supercharger is provided with an EGR device. The following Patent Document 1 describes a low-pressure loop type EGR device provided in an engine equipped with this type of supercharger. The supercharger includes a turbine provided in the exhaust passage and a compressor provided in the intake passage and driven by the turbine. In the low-pressure loop type EGR device, an EGR passage is provided between an exhaust passage downstream of the turbine and an intake passage upstream of the compressor, and an EGR valve is provided in the EGR passage. In this EGR device, the EGR gas recirculation amount is limited by closing the EGR valve as necessary in order to prevent corrosion due to condensed water generated in the EGR passage while responding to strict NOx reduction requirements. It has become.

JP 2012-229679 A

  By the way, according to the low-pressure loop type EGR device described in Patent Document 1, when the EGR valve is fully closed, EGR gas may stay in the EGR passage upstream of the EGR valve. At this time, in the EGR valve, since a fine gap may be formed between the valve seat and the valve body, it is difficult to completely eliminate the leakage of EGR gas from the upstream side to the downstream side of the EGR valve. Further, when the EGR valve is fully closed, foreign matters such as deposits may be caught between the valve seat and the valve body. In this case, EGR gas may leak from the upstream side to the downstream side of the EGR valve. The EGR gas leaked to the downstream side of the EGR valve in this way may enter the intake passage upstream of the compressor from the EGR passage. If the EGR gas is cooled under low temperature conditions after the engine is stopped, the moisture in the EGR gas May produce condensed water. If a large amount of this condensed water stays in the EGR passage downstream from the EGR valve or the intake passage upstream from the compressor, corrosion occurs in the EGR passage or the intake passage, or the accumulated large amount of condensed water flows into the combustion chamber of the engine all at once. There is a risk that it will flow and cause problems such as water hammer. In addition, when the temperature is extremely low, the condensed water freezes and the compressor may be damaged due to the scattering of ice pieces.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide condensed water generated from exhaust recirculation gas leaked to the downstream side of the exhaust recirculation valve when the exhaust recirculation valve is fully closed before externally starting the engine. It is an object of the present invention to provide an exhaust gas recirculation device for an engine with a supercharger that can be discharged into the engine.

  In order to achieve the above object, an invention according to claim 1 is provided between an intake passage and an exhaust passage of an engine, and a supercharger for boosting intake air in the intake passage, and a supercharger, Including a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, a rotating shaft that connects the compressor and the turbine so as to be integrally rotatable, and an exhaust gas discharged from the combustion chamber of the engine to the exhaust passage. An exhaust recirculation gas as an exhaust recirculation gas to the intake passage and recirculation to the combustion chamber, an exhaust recirculation valve for adjusting the flow of exhaust recirculation gas in the exhaust recirculation passage, and an exhaust recirculation passage Connected to the exhaust passage downstream of the turbine, the outlet thereof being connected to the intake passage upstream of the compressor, operating state detecting means for detecting the operating state of the engine, and detection And a control means for controlling the exhaust gas recirculation valve based on the operating state of the engine and a control means for controlling the exhaust gas recirculation valve to be fully closed when the engine is stopped. In the exhaust gas recirculation apparatus, the outlet of the exhaust gas recirculation passage is disposed at a position higher in the vertical direction than the inlet, and the condensed water is provided so as to flow down from the downstream side to the upstream side of the exhaust gas recirculation valve. The vehicle includes a driver seat door provided so as to flow down toward the exhaust passage, and the vehicle includes a driver seat door provided to correspond to the driver seat, and the vehicle includes a door opening detection means for detecting that the driver seat door is opened. When the engine is stopped, the control means detects when the door opening detection means detects that the driver's seat door has been opened in order to discharge condensed water from the downstream side to the upstream side of the exhaust gas recirculation valve. In And purpose to forcibly open the EGR valve from the fully closed state.

  According to the configuration of the above invention, when the engine is stopped, the door opening detection means detects that the driver's seat door has been opened in order to discharge condensed water from the downstream side to the upstream side of the exhaust gas recirculation valve. When detected, the exhaust gas recirculation valve is forcibly opened from the fully closed state. Here, even if the exhaust gas recirculation valve is controlled according to the operating state of the engine as usual after the engine is started, it takes a few seconds to surely start the engine after the driver's door is opened. Therefore, during this time, the exhaust gas recirculation valve is forcibly opened, so that the condensed water accumulated on the downstream side of the exhaust gas recirculation valve flows from the downstream side to the upstream side of the exhaust gas recirculation valve, and further exhausts the exhaust gas recirculation passage. It flows down to the passage and is discharged outside.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the control means detects the opening of the driver's seat door after the door opening detecting means detects that the engine door has been opened. The purpose is to return the exhaust gas recirculation valve from the forced open state to the fully closed state when it is detected by the operating state detecting means.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, after the exhaust gas recirculation valve is forcibly opened, the exhaust gas recirculation valve is brought into a forced open state when the engine is started. Since it is returned to the fully closed position, a certain amount of time can be secured from when the driver's seat door is opened until the engine is started.

  In order to achieve the above object, according to a third aspect of the present invention, in the first aspect of the present invention, the control means is configured to recirculate exhaust gas as time elapses after the exhaust recirculation valve is forcibly opened. The purpose is to return the valve from the forced open state to the fully closed state.

  According to the configuration of the invention, in addition to the operation of the invention according to claim 1, after the exhaust gas recirculation valve is forcibly opened, the exhaust gas recirculation valve is forced to open in accordance with the passage of time thereafter. Therefore, even if the engine does not start, the exhaust gas recirculation valve is not left in a forced open state.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the operating state detecting means is a cooling water temperature for detecting the temperature of the engine cooling water. A detecting means, and the control means, when the door opening detecting means detects that the driver's seat door is opened, if the detected coolant temperature is not lower than a predetermined temperature, the control means The purpose is not to forcibly open the valve from the fully closed state.

  According to the configuration of the above invention, in addition to the operation of the invention according to any one of claims 1 to 3, the moisture in the exhaust gas recirculation gas if the temperature of the engine is not relatively high even when the driver's door is opened. In this case, the exhaust gas recirculation valve is not opened unnecessarily.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the control means detects that the driver's door has been opened by the door open detection means. The purpose is to forcibly open the exhaust gas recirculation valve from the fully closed state only when there is no history of forcibly opening the exhaust gas recirculation valve most recently.

  According to the configuration of the invention, in addition to the operation of the invention according to any one of claims 1 to 4, there is a history of forcibly opening the exhaust gas recirculation valve immediately after the driver's seat door is opened. Therefore, the exhaust gas recirculation valve is not forcibly opened again, and the exhaust gas recirculation valve is not opened unnecessarily.

  In order to achieve the above object, according to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the intake passage is formed with a recess around the outlet of the exhaust gas recirculation passage. Is arranged at the lowest position of the recess.

  According to the configuration of the invention, in addition to the action of the invention according to any one of claims 1 to 5, a recess is formed around the outlet of the exhaust gas recirculation passage in the intake passage, and the outlet is at the lowest position of the recess. Therefore, the condensed water generated inside the intake passage is collected in the recess, and the condensed water is reliably guided from the outlet of the exhaust gas recirculation passage to the passage.

  According to the first aspect of the present invention, the condensed water generated from the exhaust recirculation gas leaked to the downstream side of the exhaust recirculation valve when the exhaust recirculation valve is fully closed can be discharged to the outside before the engine is started.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the condensed water can be reliably discharged to the outside before the engine is started.

  According to the third aspect of the invention, in addition to the effect of the first aspect of the invention, the exhaust gas recirculation valve is not left open and unnecessary exhaust gas is restarted when the engine is started next time. It is possible to prevent the reflux gas from flowing into the intake passage.

  According to the invention of claim 4, in addition to the effect of the invention of any one of claims 1 to 3, the frequency of use of the exhaust gas recirculation valve can be minimized, and the durability of the exhaust gas recirculation valve is improved. This can improve the battery power consumption.

  According to the invention of claim 5, in addition to the effect of the invention of any of claims 1 to 4, the frequency of use of the exhaust gas recirculation valve can be minimized, and the durability of the exhaust gas recirculation valve can be improved. This can improve the battery power consumption.

  According to the invention described in claim 6, in addition to the effect of the invention described in any one of claims 1 to 5, it is possible to prevent the condensed water generated in the intake passage upstream from the compressor from entering the compressor. And the compressor can be protected from condensed water.

The schematic block diagram which shows the gasoline engine system which concerns on one Embodiment and contains the EGR apparatus of the engine with a supercharger. Sectional drawing which concerns on one Embodiment and is a part of EGR channel | path, and expands and shows the part in which an EGR valve is provided. 1 is a plan view illustrating an outline of a vehicle according to an embodiment. The flowchart which concerns on one Embodiment and shows an example of the processing content of condensed water discharge | emission control.

  Hereinafter, an embodiment of an exhaust gas recirculation device (EGR device) for a supercharged engine according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a gasoline engine system including an EGR device for an engine with a supercharger in this embodiment. This engine system is mounted on an automobile and includes a reciprocating type engine 1. An intake passage 3 is connected to the intake port 2 of the engine 1, and an exhaust passage 5 is connected to the exhaust port 4. An air cleaner 6 is provided at the inlet of the intake passage 3. A supercharger 7 for boosting the intake air in the intake passage 3 is provided in the intake passage 3 downstream of the air cleaner 6 between the exhaust passage 5 and the intake passage 3.

  The supercharger 7 includes a compressor 8 disposed in the intake passage 3, a turbine 9 disposed in the exhaust passage 5, and a rotating shaft 10 that connects the compressor 8 and the turbine 9 so as to be integrally rotatable. The supercharger 7 rotates the turbine 9 by the exhaust gas flowing through the exhaust passage 5 and integrally rotates the compressor 8 via the rotary shaft 10 to boost the intake air in the intake passage 3, that is, perform supercharging. It is like that.

  An exhaust bypass passage 11 that bypasses the turbine 9 is provided in the exhaust passage 5 adjacent to the supercharger 7. A waste gate valve 12 is provided in the exhaust bypass passage 11. By adjusting the exhaust gas flowing through the exhaust bypass passage 11 by the waste gate valve 12, the exhaust gas flow rate supplied to the turbine 9 is adjusted, the rotational speeds of the turbine 9 and the compressor 8 are adjusted, and supercharging by the supercharger 7 is performed. The pressure is adjusted.

  In the intake passage 3, an intercooler 13 is provided between the compressor 8 of the supercharger 7 and the engine 1. The intercooler 13 is for cooling the intake air that has been pressurized by the compressor 8 to a high temperature. A surge tank 3 a is provided in the intake passage 3 between the intercooler 13 and the engine 1. The intake passage 3 downstream of the intercooler 13 and upstream of the surge tank 3a corresponds to an example of an intake air amount adjusting valve of the present invention, and is provided with an electronic throttle device 14 that is an electric throttle valve. The electronic throttle device 14 detects a butterfly throttle valve 21 disposed in the intake passage 3, a DC motor 22 for opening and closing the throttle valve 21, and an opening degree (throttle opening degree) TA of the throttle valve 21. And a throttle sensor 23 for performing the operation. The electronic throttle device 14 is configured such that the opening degree of the throttle valve 21 is adjusted by the throttle valve 21 being opened and closed by the DC motor 22 in accordance with the operation of the accelerator pedal 26 by the driver. The exhaust passage 5 downstream from the turbine 9 is provided with a catalytic converter 15 as an exhaust catalyst for purifying exhaust.

  The engine 1 is provided with an injector 25 for injecting and supplying fuel to the combustion chamber 16. Fuel is supplied to the injector 25 from a fuel tank (not shown). The engine 1 is provided with a spark plug 29 corresponding to each cylinder. Each spark plug 29 is ignited by receiving a high voltage output from the igniter 30. The ignition timing of each spark plug 29 is determined by the high voltage output timing from the igniter 30. The spark plug 29 and the igniter 30 constitute an ignition device.

  In this embodiment, the EGR device causes an exhaust gas recirculation passage (EGR passage) to flow a part of the exhaust discharged from the combustion chamber 16 of the engine 1 to the exhaust passage 5 as EGR gas to the intake passage 3 and recirculate to the combustion chamber 16. 17 and an exhaust gas recirculation valve (EGR valve) 18 provided in the EGR passage 17 in order to adjust the flow of EGR gas in the EGR passage 17. The EGR device is a low-pressure loop type, and the EGR passage 17 is provided between the exhaust passage 5 downstream from the catalytic converter 15 and the intake passage 3 upstream from the compressor 8. That is, the outlet 17 a of the EGR passage 17 is connected to the intake passage 3 upstream from the compressor 8. Further, the inlet 17 b of the EGR passage 17 is connected to the exhaust passage 5 downstream from the catalytic converter 15. The EGR passage 17 is provided with an EGR cooler 20 for cooling the EGR gas flowing through the passage 17. In this embodiment, the EGR valve 18 is disposed in the EGR passage 17 downstream of the EGR cooler 20.

  FIG. 2 is an enlarged sectional view showing a part of the EGR passage 17 where the EGR valve 18 is provided. As shown in FIGS. 1 and 2, the EGR valve 18 is configured as a poppet valve and as an electric valve. That is, the EGR valve 18 includes a valve body 32 that is driven by the DC motor 31. The valve body 32 has a substantially conical shape, and is provided so as to be seated on a valve seat 33 provided in the EGR passage 17. The DC motor 31 includes an output shaft 34 that is configured to be able to reciprocate (stroke) in a straight line. A valve body 32 is fixed to the tip of the output shaft 34. The output shaft 34 is supported by a housing constituting the EGR passage 17 via a bearing 35. The opening degree of the valve body 32 with respect to the valve seat 33 is adjusted by moving the output shaft 34 of the DC motor 31 in a stroke. The output shaft 34 of the EGR valve 18 is provided so as to be able to perform a stroke movement by a predetermined stroke L1 from a fully closed state in which the valve body 32 is seated on the valve seat 33 to a fully open state in which the valve body 32 contacts the bearing 35. . In the EGR device of this embodiment, the opening area of the valve seat 33 is enlarged for the EGR valve 18 as compared with the conventional technique in order to realize a large amount of EGR. Accordingly, the valve body 32 is enlarged.

  As shown in FIG. 1, in this embodiment, the outlet 17a of the EGR passage 17 is arranged at a higher position in the vertical direction than the inlet 17b. Further, the condensed water is provided so as to flow down from the downstream side to the upstream side of the EGR valve 18, and the condensed water is provided so as to flow down toward the exhaust passage 5 through the EGR passage 17. More specifically, as shown in FIGS. 1 and 2, in the EGR passage 17, the EGR valve 18 is arranged such that the valve body 32 and the output shaft 34 perform stroke motion in the vertical direction. Further, the EGR passage 17 upstream from the EGR valve 18 is disposed so as to extend vertically in a portion near the EGR valve 18 and to incline downward toward the exhaust passage 5 in a portion further upstream. An EGR cooler 20 is disposed in the inclined portion of the EGR passage 17. On the other hand, the EGR passage 17 downstream of the EGR valve 18 is inclined upward toward the downstream side in the immediate vicinity of the EGR valve 18, and the further downstream portion is arranged vertically toward the intake passage 3. An inclined portion of the EGR passage 17 downstream from the EGR valve 18 serves as a trap 45 for collecting condensed water. Thereby, when the EGR valve 18 is fully closed, the condensed water generated by the EGR gas leaked from the upstream side to the downstream side of the EGR valve 18 is collected in the trap 45. Yes. The shape and arrangement of the valve seat 33 of the EGR valve 18 are such that the condensed water collected in the trap 45 flows down from the downstream side to the upstream side of the EGR valve 18 when the EGR valve 18 is opened. Is set.

  Therefore, the condensed water generated on the downstream side of the EGR valve 18 does not flow to the intake passage 3 due to the height difference between the EGR valve 18 and the outlet 17a of the EGR passage 17. The condensed water flowing down from the downstream side of the EGR valve 18 flows down from the EGR passage 17 toward the exhaust passage 5 due to a difference in height between the EGR valve 18 and the inlet 17 b of the EGR passage 17. The condensed water flowing down to the exhaust passage 5 is discharged to the outside together with the exhaust.

  In this embodiment, the intake passage 3 is formed with a recess 3 b around the outlet 17 a of the EGR passage 17. Here, the bottom wall of the recess 3b has a tapered shape that inclines downward from the outer periphery of the recess 3b toward the center of the recess 3b. The outlet 17a of the EGR passage 17 is disposed at the lowest position of the recess 3b. Therefore, the condensed water generated in the intake passage 3 upstream from the compressor 8 is collected in the recess 3 b and flows down from the outlet 17 a of the EGR passage 17 toward the trap 45 of the EGR passage 17.

  In addition, in the engine 1 of this embodiment, the blow-by gas leaking from the combustion chamber 16 into the crankcase 1b and the cylinder head (including the head cover) 1c flows into the intake passage 3 and is returned to the combustion chamber 16. A gas reduction device is provided. As shown in FIG. 1, the blow-by gas reduction device includes a gas reduction passage 61, a PCV valve 62, and a scavenging passage 63. The gas reduction passage 61 is configured to flow blow-by gas generated in the engine 1 to the intake passage 3 using negative pressure. The gas reduction passage 61 has an inlet side connected to the cylinder head 1 c via the PCV valve 62 and an outlet side connected to the intake passage 3 upstream of the compressor 8. The PCV valve 62 is configured to operate under a negative pressure in order to adjust the flow rate of blow-by gas flowing into the gas reduction passage 61. Here, when the engine 1 is in operation, if intake air flows into the intake passage 3 and the intake passage 3 upstream of the compressor 8 has a negative pressure, the negative pressure passes through the gas reduction passage 61 and the PCV valve 62 to the cylinder head 1c. Acts inside. Upon receiving this negative pressure, the PCV valve 62 opens, and blow-by gas flows from the cylinder head 1 c to the intake passage 3 upstream of the compressor 8 through the PCV valve 62 and the gas reduction passage 61. The blow-by gas that has flowed into the intake passage 3 is taken into the combustion chamber 16 together with the intake air. The scavenging passage 63 is configured to introduce fresh air into the cylinder head 1 c in order to scavenge the inside of the cylinder head 1 c when blow-by gas flows from the cylinder head 1 c to the intake passage 3. Here, the moisture contained in the blow-by gas is also collected in the recess 3 b of the intake passage 3 and flows down from the outlet 17 a of the EGR passage 17 toward the trap 45 of the EGR passage 17.

  In this embodiment, in order to execute fuel injection control, ignition timing control, intake air amount control, EGR control, and the like according to the operating state of the engine 1, the injector 25, the igniter 30, the DC motor 22 of the electronic throttle device 14, and The DC motor 31 of the EGR valve 18 is controlled by an electronic control unit (ECU) 50 in accordance with the operating state of the engine 1. The ECU 50 stores in advance a central processing unit (CPU), a predetermined control program and the like, various memories for temporarily storing a calculation result of the CPU, and the like, an external input circuit connected to these parts, and an external And an output circuit. The ECU 50 corresponds to an example of a control unit of the present invention. An igniter 30, an injector 25, a DC motor 22, and a DC motor 31 are connected to the external output circuit. The external input circuit is connected to various sensors 27, 51 to 58 corresponding to an example of the operating state detecting means of the present invention for detecting the operating state of the engine 1 including the throttle sensor 23, and various engine signals are inputted. It has come to be.

  Here, in addition to the throttle sensor 23, various sensors include an accelerator sensor 27, an intake pressure sensor 51, a rotation speed sensor 52, a water temperature sensor 53, an air flow meter 54, an air-fuel ratio sensor 55, an intake air temperature sensor 56, an ignition switch 57, and A door sensor 58 is provided. The accelerator sensor 27 detects an accelerator opening ACC that is an operation amount of the accelerator pedal 26. The intake pressure sensor 51 detects the intake pressure PM in the surge tank 3a. That is, the intake pressure sensor 51 detects the intake pressure PM in the surge tank 3 a downstream from the throttle valve 21. The rotational speed sensor 52 detects the rotational angle (crank angle) of the crankshaft 1a of the engine 1 and detects the change in the crank angle as the rotational speed (engine rotational speed) NE of the engine 1. The water temperature sensor 53 detects the cooling water temperature THW of the engine 1 and corresponds to an example of the cooling water temperature detection means of the present invention. The air flow meter 54 detects the intake air amount Ga flowing through the intake passage 3 immediately downstream of the air cleaner 6. The air-fuel ratio sensor 55 is provided in the exhaust passage 5 immediately upstream of the catalytic converter 15, and detects the air-fuel ratio A / F in the exhaust. An intake air temperature sensor 56 provided in the air cleaner 6 detects the temperature of intake air (intake air temperature) THA taken into the intake passage 3. FIG. 3 is a plan view schematically showing the vehicle 71. As shown in FIG. 3, the ignition switch 57 is provided at the driver's seat of the vehicle 71 and is operated by the driver to start or stop the engine 1 and outputs an operation signal thereof. The door sensor 58 is provided to detect the opening of the driver's seat door 72 of the vehicle 71, and outputs an open signal when the driver's seat door 72 is opened as shown by a two-dot chain line in FIG. Yes.

  In this embodiment, the ECU 50 controls the EGR valve 18 in order to execute EGR control in accordance with the operation state of the engine 1 in the entire operation region of the engine 1. Further, the ECU 50 normally controls the opening of the EGR valve 18 based on the operation state detected during the acceleration operation or the steady operation of the engine 1, and when the engine 1 is stopped, during the idle operation or during the deceleration operation, the EGR valve 18. Is controlled to be fully closed.

  In this embodiment, the ECU 50 controls the electronic throttle device 14 based on the accelerator opening ACC in order to drive the engine 1 in response to a driver's request. Further, the ECU 50 controls to open the electronic throttle device 14 based on the accelerator opening ACC during acceleration operation or steady operation of the engine 1 and closes the electronic throttle device 14 when the engine 1 is stopped or decelerated. It has become. Thereby, the throttle valve 21 is opened during the acceleration operation or the steady operation of the engine 1 and is fully closed when the engine 1 is stopped or decelerated.

  Here, in this low-pressure loop type EGR device, when the EGR valve 18 is fully closed, EGR gas leaked from the upstream side to the downstream side of the EGR valve 18 is passed through the EGR passage 17 downstream from the EGR valve 18 or the compressor 8. There is a possibility that it enters the upstream intake passage 3 and is cooled under low temperature conditions (including when the engine 1 is not warmed up) such as after the engine 1 is stopped to generate condensed water. If this condensed water stays in a large amount in the EGR passage 17 downstream of the EGR valve 18 or the intake passage 3 upstream of the compressor 8, the EGR passage 17 or the intake passage 3 is corroded or a large amount of condensed water burns. There is a possibility that problems such as water hammer may occur due to a sudden flow into the chamber 16. Therefore, in this embodiment, the ECU 50 condenses as follows in order to discharge condensed water generated from the EGR gas leaked to the downstream side of the EGR valve 18 when the EGR valve 18 is fully closed before starting the engine 1. Water discharge control is implemented.

  FIG. 4 is a flowchart showing an example of the processing content of the condensed water discharge control. When the process proceeds to this routine, first, at step 100, the ECU 50 determines whether or not IG (ignition) is off. That is, the ECU 50 determines whether the ignition switch 57 is off. If this determination is negative, the ECU 50 proceeds to step 240. If the determination result is affirmative, the ECU 50 proceeds to step 110.

  In step 110, the ECU 50 determines whether or not the driver's seat door is opened. That is, the ECU 50 determines whether or not an open signal is output from the door sensor 58. When this determination result is negative, the ECU 50 proceeds to step 130 as it is. If the determination result is affirmative, the ECU 50 proceeds to step 120.

  In step 120, the ECU 50 sets the door opening flag XDO to “1” because the driver's seat door is once opened.

  Next, in step 130, the ECU 50 determines whether or not the door open flag XDO is “1”, that is, whether or not the driver's seat door is once opened. When this determination result is negative, the ECU 50 returns the process to step 100 as it is. If the determination result is affirmative, the ECU 50 proceeds to step 140.

  In step 140, the ECU 50 stands by for engine control. That is, the ECU 50 waits in a state where fuel injection control other than EGR control, ignition timing control, and intake air amount control can be performed at any time.

  Next, at step 150, the ECU 50 determines whether or not the EGR valve opening flag XEO is “0”. The flag XEO is set to “1” when the EGR valve 18 is opened, and is set to “0” when the EGR valve 18 is fully closed. The ECU 50 can determine from this flag XEO whether there is a history of forcibly opening the EGR valve 18 immediately before the engine 1 is operated once. If this determination result is negative, the ECU 50 proceeds to step 200 because the EGR valve 18 is open. If this determination result is affirmative, the ECU 50 proceeds to step 160 because the EGR valve 18 is fully closed.

  In step 160, the ECU 50 determines whether or not the cooling water temperature THW detected by the water temperature sensor 53 is lower than a predetermined reference temperature T1 (for example, “50 ° C.”). If this determination result is negative, the temperature of the engine 1 is not relatively low enough to condense the moisture in the EGR gas, and the ECU 50 proceeds to step 220. If the determination result is affirmative, the temperature of the engine 1 is relatively low enough to condense the moisture in the EGR gas, and thus the ECU 50 proceeds to step 170.

  In step 170, the ECU 50 forcibly opens the EGR valve 18 from the fully closed state assuming that the temperature of the engine 1 is relatively low and condensed water is generated. In step 180, the ECU 50 sets the EGR valve opening flag XEO to “1”.

  Thereafter, in step 190, the ECU 50 captures a post-opening time TEO, which is an elapsed time since the EGR valve 18 is forcibly opened. The ECU 50 separately counts the post-valve time TEO. Thereafter, the ECU 50 returns the process to step 100.

  On the other hand, in step 200 after shifting from step 150, the ECU 50 determines whether or not the post-valve opening time TEO exceeds a predetermined reference time A1 (for example, “3 to 5 seconds”). That is, the ECU 50 determines whether or not a predetermined reference time A1 has elapsed after the driver's seat door 72 is once opened. If this determination is negative, the ECU 50 returns the process to step 100 as it is. If this determination result is affirmative, the ECU 50 proceeds to step 210 assuming that sufficient time has elapsed for completion of the condensed water discharge.

  In step 210, the ECU 50 returns the EGR valve 18 from the forced open state to the fully closed state.

  Next, in step 220 after shifting from step 160 or step 210, the ECU 50 cancels engine control standby.

  In step 230, the ECU 50 resets the door open flag XDO to “0” and returns the process to step 100.

  On the other hand, since the process is shifted from step 100 to step 240 and IG is ON, the ECU 50 determines whether or not the EGR valve open flag XEO is “1”. If this determination result is negative, since there is no history of forcibly opening the EGR valve 18 most recently (for example, the previous control cycle), the ECU 50 proceeds to step 260 as it is. If the determination result is affirmative, the EGR valve 18 has already been forcibly opened, and the ECU 50 proceeds to step 250.

  In step 250, the ECU 50 returns the EGR valve 18 from the forced open state to the fully closed state.

  Thereafter, the process proceeds from step 240 or step 250, and in step 260, the ECU 50 determines whether or not the engine 1 has been started. The ECU 50 can make this determination based on, for example, the engine rotational speed NE detected by the rotational speed sensor 52. If this determination is negative, the ECU 50 returns the process to step 100 as it is. If the determination result is affirmative, the ECU 50 proceeds to step 270.

  In step 270, the ECU 50 resets the EGR valve open flag XEO to “0” because the engine 1 has started.

  In step 280, the ECU 50 normally controls the EGR valve 18. That is, the EGR valve 18 is controlled in order to execute normal EGR control based on the operating state of the engine 1. The description of the EGR control is omitted here. Thereafter, the ECU 50 returns the process to step 100.

  According to the EGR device for an engine with a supercharger of this embodiment described above, the ECU 50 allows the driver's seat door to discharge condensed water from the downstream side to the upstream side of the EGR valve 18 when the engine 1 is stopped. When the door sensor 58 detects that 72 is opened, the EGR valve 18 is forcibly opened from the fully closed state. Here, even if the EGR valve 18 is controlled in accordance with the operation state of the engine 1 as usual after the engine 1 is started, it takes a few seconds to reliably start the engine 1 after the driver's seat door 72 is opened. Cost. Accordingly, the EGR valve 18 is forcibly opened during this time, so that the condensed water accumulated on the downstream side of the EGR valve 18 flows from the downstream side to the upstream side of the EGR valve 18 and further exhausts through the EGR passage 17. It flows down toward the passage 5 and is discharged to the outside. For this reason, the condensed water generated from the EGR gas leaked to the downstream side of the EGR valve 18 when the EGR valve 18 is fully closed can be discharged to the outside before the engine 1 is started. Further, it is possible to prevent a large amount of condensed water generated from the EGR gas leaking to the downstream side of the EGR valve 18 when the EGR valve 18 is fully closed from staying on the downstream side of the EGR valve 18. As a result, it is possible to prevent corrosion caused by condensed water in the EGR passage 17 downstream from the EGR valve 18 and the intake passage 3 upstream from the compressor 8, and a large amount of condensed water is prevented from being generated in the combustion chamber 16 of the engine 1. Can be prevented in advance, and problems such as water hammer can be prevented.

  In this embodiment, the ECU 50 forces the EGR valve 18 when the rotational speed sensor 52 detects that the engine 1 has started after the door sensor 58 detects that the driver's seat door 72 has been opened. The valve is returned from the open state to the fully closed state. Accordingly, when the engine 1 is started after the EGR valve 18 is forcibly opened, the EGR valve 18 is returned to the fully closed state from the forcibly opened state, so that the engine is opened after the driver's seat door 72 is opened. A certain amount of time can be secured until 1 starts. Therefore, the condensed water generated from the EGR gas leaked to the downstream side of the EGR valve 18 when the EGR valve 18 is fully closed can be surely discharged to the outside before the engine 1 is started.

  In this embodiment, the ECU 50 is configured to return the EGR valve 18 from the forcibly opened state to the fully closed state as time elapses after the EGR valve 18 is forcibly opened. Therefore, after the EGR valve 18 is forcibly opened, the EGR valve 18 is returned to the fully closed state from the forcibly opened state as time passes thereafter, so that even if the engine 1 does not start, The EGR valve 18 is not left in a forced open state. Therefore, the EGR valve 18 is not left open and it is possible to prevent unnecessary EGR gas from flowing into the intake passage 3 when the engine 1 is started next time.

  In this embodiment, when the coolant temperature THW detected by the water temperature sensor 53 is not lower than the predetermined reference temperature T1 when the door sensor 58 detects that the driver's seat door 72 is opened, the ECU 50 performs EGR. The valve 18 is not forcibly opened from the fully closed state. Therefore, even if the driver's seat door 72 is opened, if the temperature of the engine 1 is relatively high, condensed water is not generated from the moisture in the EGR gas. In this case, the EGR valve 18 may be opened unnecessarily. Absent. For this reason, the usage frequency of the EGR valve 18 can be minimized, the durability of the EGR valve 18 can be improved, and the use of battery power can be suppressed.

  In this embodiment, when the door sensor 58 detects that the driver's seat door 72 is opened, the ECU 50 opens the EGR valve 18 only when there is no history of forcibly opening the EGR valve 18 most recently. The valve is forcibly opened from the closed state. Therefore, even if the driver's seat door 72 is opened, if there is a history that the EGR valve 18 has been forcibly opened recently, the EGR valve 18 is not forcibly opened again, and the EGR valve 18 is wasted. The valve is never opened. Also in this sense, the usage frequency of the EGR valve 18 can be minimized, the durability of the EGR valve 18 can be improved, and the use of battery power can be suppressed.

  In this embodiment, in the intake passage 3 upstream from the compressor 8, a recess 3b is formed around the outlet 17a of the EGR passage 17, and the outlet 17a is arranged at the lowest position of the recess 3b. Therefore, the condensed water generated inside the intake passage 3 is collected in the recess 3 b, and the condensed water is reliably guided from the outlet 17 a of the EGR passage 17 to the passage 17. For this reason, it is possible to prevent the condensed water generated in the intake passage 3 upstream from the compressor 8 from entering the compressor 8 and to protect the compressor 8 from the condensed water.

  Here, if the lowest part of the inner wall of the intake passage 3 upstream of the compressor 8 is set at the same level as the lowest part of the inlet of the compressor 8, the condensed water generated in the intake passage 3 upstream of the compressor 8 Water accumulates due to tension. If the condensed water freezes and hardens, the frozen pieces may be sucked into the compressor 8 when the engine 1 is started and the compressor 8 may be damaged. Further, when the lowest part of the inner wall of the intake passage 3 upstream from the compressor 8 is made higher than the lowest part of the inlet of the compressor 8, the condensed water generated in the intake passage 3 upstream from the compressor 8 may flow down to the compressor 8. There is. On the other hand, when the lowest part of the inner wall of the intake passage 3 upstream of the compressor 8 is made lower than the lowest part of the inlet of the compressor 8, the condensed water generated in the intake passage 3 upstream of the compressor 8 is contained in the intake passage 3. It accumulates in. If the condensed water freezes and hardens, the frozen pieces may be sucked into the compressor 8 when the engine 1 is started and the compressor 8 may be damaged. On the other hand, in this embodiment, the condensed water generated in the intake passage 3 upstream from the compressor 8 flows down from the recess 3b to the EGR passage 17, so that the condensed water and its icing pieces are sucked into the compressor 8. There is no.

  In this embodiment, since the trap 45 is provided on the downstream side of the EGR valve 18, the condensed water generated on the downstream side of the EGR valve 18 is reliably collected by the trap 45. When the EGR valve 18 is forcibly opened, the collected condensed water flows down from the trap 45 to the upstream side of the EGR valve 18 and further to the exhaust passage 5 and is discharged to the outside. For this reason, the condensed water produced on the downstream side of the EGR valve 18 can be reliably collected and discharged naturally to the exhaust passage 5 by gravity.

  In this embodiment, since the EGR valve 18 is forcibly opened and then always returned to the fully closed state, there is no hindrance to the normal control of the EGR valve 18 thereafter. Therefore, it is possible to prevent EGR gas from being inadvertently taken into the combustion chamber 16 after the EGR valve 18 is forcibly opened, and the operation of the engine 1 becomes unstable due to the EGR gas. Can be prevented.

  Further, in this embodiment, since the EGR valve 18 is forcibly opened before the engine 1 is started, EGR gas does not flow from the EGR passage 17 to the intake passage 3, and the EGR passage before the engine 1 is started. No EGR gas remains in 18 and unnecessary EGR gas is not taken into the combustion chamber 16 through the intake passage 3. For this reason, deterioration of the startability of the engine 1 due to EGR gas can be prevented.

  In addition, this invention is not limited to the said embodiment, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.

  For example, in the embodiment, the EGR valve 18 is configured as a poppet valve and an electric valve, but the EGR valve may be configured as a butterfly valve and an electric valve.

  The present invention can be used for an automobile engine regardless of, for example, a gasoline engine or a diesel engine.

DESCRIPTION OF SYMBOLS 1 Engine 3 Intake passage 3a Surge tank 3b Recess 5 Exhaust passage 7 Supercharger 8 Compressor 9 Turbine 10 Rotating shaft 16 Combustion chamber 17 EGR passage 17a Outlet 17b Inlet 18 EGR valve 50 ECU (control means)
52 Rotational speed sensor (Operating state detection means)
53 Water temperature sensor (operating state detection means, cooling water temperature detection means)
57 Ignition switch (Operating state detection means)
58 Door sensor (door open detection means)
71 Vehicle 72 Driver's seat door

Claims (6)

A turbocharger provided between an intake passage and an exhaust passage of the engine for boosting intake air in the intake passage;
The supercharger includes a compressor disposed in the intake passage, a turbine disposed in the exhaust passage, and a rotation shaft that connects the compressor and the turbine so as to be integrally rotatable.
An exhaust gas recirculation passage for causing a part of the exhaust gas discharged from the combustion chamber of the engine to flow into the intake passage as an exhaust gas recirculation gas to be recirculated to the combustion chamber;
An exhaust gas recirculation valve for adjusting the flow of the exhaust gas recirculation gas in the exhaust gas recirculation passage;
The exhaust gas recirculation passage has an inlet connected to the exhaust passage downstream of the turbine and an outlet connected to the intake passage upstream of the compressor;
An operating state detecting means for detecting the operating state of the engine;
Control means for controlling the exhaust gas recirculation valve based on the detected operating state;
In the exhaust gas recirculation apparatus for an engine with a supercharger mounted on a vehicle, the control means includes: controlling the exhaust gas recirculation valve to be fully closed when the engine is stopped.
The outlet of the exhaust gas recirculation passage is disposed at a position higher in the vertical direction than the inlet, and is provided so that condensed water can flow from the downstream side to the upstream side of the exhaust gas recirculation valve. Is provided to flow down toward the exhaust passage,
The vehicle includes a driver's seat door provided corresponding to the driver's seat, and the vehicle is provided with door opening detection means for detecting that the driver's seat door is opened,
When the engine is stopped, the control means detects that the driver's seat door has been opened in order to discharge the condensed water from the downstream side to the upstream side of the exhaust gas recirculation valve. An exhaust gas recirculation device for an engine with a supercharger, wherein when detected, the exhaust gas recirculation valve is forcibly opened from a fully closed state.   The control means sets the exhaust gas recirculation valve when the operating state detecting means detects that the engine has started after the door opening detecting means detects that the driver seat door has been opened. 2. The exhaust gas recirculation device for an engine with a supercharger according to claim 1, wherein the exhaust valve is returned from a forced open state to a fully closed state.   2. The control unit according to claim 1, wherein the control unit returns the exhaust gas recirculation valve from the forced open state to a fully closed state as time elapses after the exhaust gas recirculation valve is forcibly opened. Exhaust gas recirculation device for supercharged engines. The operating state detecting means includes a cooling water temperature detecting means for detecting a temperature of the cooling water of the engine,
When the detected temperature of the cooling water is not lower than a predetermined temperature when the door opening detecting means detects that the driver's door has been opened, the control means controls the exhaust recirculation valve. The exhaust gas recirculation device for a supercharged engine according to any one of claims 1 to 3, wherein the valve is not forcibly opened from a fully closed state.   When the door opening detection means detects that the driver's seat door has been opened, the control means is provided only when there is no recent history of forcibly opening the exhaust recirculation valve. The exhaust gas recirculation device for an engine with a supercharger according to any one of claims 1 to 4, wherein the valve is forcibly opened from a fully closed state.   6. The intake passage according to claim 1, wherein a recess is formed around the outlet of the exhaust gas recirculation passage, and the outlet is disposed at a lowest position of the recess. Exhaust gas recirculation device for turbocharged engines.

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