JP2014074356A - Engine condensed water discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control discharge of condensed water, generated while a vehicle travels, from an air intake passage to an exhaust passage while the vehicle travels and when a key is turned off after an engine stops.SOLUTION: An engine condensed water discharge device comprises: an electrically-assisted turbocharger 21 which can control supercharging pressure in an air intake passage 12 without relying on a travel state of a vehicle by driving a motor-generator; and an intercooler 22. The engine condensed water discharge device also has: a condensed water storage tank 23; a bypass passage 24 which communicate the condensed water storage tank 23 with a downstream side of the electrically-assisted turbocharger 21 in an exhaust passage 13; an on-off valve 25 installed in the bypass passage 24; and an ECU 42 which controls drive of the electrically-assisted turbocharger and an opening/closing state of the on-off valve 25. With the engine condensed water discharge device, discharge of condensed water generated while a vehicle travels is controlled to be performed from the air intake passage 12 to the exhaust passage 13 while the vehicle travels and when a key is turned off after an engine stops.

Description

  The present invention relates to a condensed water discharge device for an engine.

  In an internal combustion engine equipped with a low pressure EGR (Exhaust Gas Recirculation), when the EGR gas that has come out of the low pressure EGR passes through the intercooler, moisture in the gas is condensed and condensed water is generated. Accumulate downstream.

  Patent Document 1 below discloses a technology for preventing corrosion of the intake manifold due to condensed water by providing a condensed water discharge port downstream of the intercooler and connecting a drain pipe connected to the condensed water discharge port to the exhaust passage. Is disclosed.

  In Patent Document 2 below, the condensate collected in the tank is controlled by opening and closing the open / close valve and the drain valve based on the detection output of the water level sensor that detects the level of the condensate collected in the tank that stores the condensate. A technique for appropriately and automatically discharging condensed water according to the amount of water is disclosed.

  In Patent Document 3 below, by installing a condensate removal device on the underside of the intake manifold, it is possible to avoid the accumulation of water in the intake system without manual operation, greatly reducing the amount of condensate discharged from the drain pipe. Techniques to do this are disclosed.

JP 2000-27715 A JP 2011-241797 A JP 2004-176691 A

  If the engine is stopped and the key is turned off while condensate has accumulated in the downstream of the intercooler, the condensate freezes and closes the intake passage in conditions such as cold or winter, making it difficult to restart the engine. It may cause symptoms such as becoming.

  Therefore, an object of the present invention is to perform control for discharging condensed water generated during vehicle travel from the intake passage to the exhaust passage during vehicle travel and when the key is turned off after the engine is stopped.

The condensed water discharge device for an engine according to the first invention for solving the above-mentioned problem is
This is a condensate drainage device for an engine comprising an electric assist turbocharger and an intercooler that can control the supercharging pressure in the intake passage without depending on the running state of the vehicle when the motor generator is driven. And
In the intake passage, a condensed water storage tank provided on the downstream side of the intercooler;
A bypass passage communicating the condensed water storage tank and the downstream side of the electrically assisted turbocharger in the exhaust passage;
An on-off valve provided in the bypass passage;
Control means for controlling the driving of the electric assist turbocharger and the open / close state of the on-off valve;
The control means forces the condensed water stored in the condensed water storage tank to the exhaust passage through a bypass passage by driving the electric assist turbocharger and opening the on-off valve under a predetermined condition. It is characterized in that the condensate discharge control is performed.

The condensed water discharge device for an engine according to the second invention for solving the above-mentioned problems is
In the condensed water discharge device for an engine according to the first aspect of the invention,
The control means performs the condensed water discharge control when it is determined that the vehicle is stopped and the key is OFF.

An engine condensate discharge device according to a third aspect of the present invention for solving the above problem
In the condensed water discharge device for an engine according to the first or second invention,
The control means performs the condensed water discharge control when it is determined that the vehicle is running and is in a decelerating state.

An engine condensed water discharger according to a fourth aspect of the present invention for solving the above-described problem is
In the condensed water discharge device for an engine according to the first or second invention,
The control means stops the condensed water discharge control when it is determined that the boost passage in the intake passage has occurred.

An engine condensed water discharger according to a fifth aspect of the present invention for solving the above-described problem is
In the condensed water discharge device for an engine according to any one of the first to fourth inventions,
In the intake passage, provided with a throttle valve provided downstream of the condensed water storage tank,
During the condensed water discharge control, the control means further controls the throttle valve to be in a closed state.

An engine condensate discharge device according to a sixth aspect of the present invention for solving the above problems
In the condensed water discharge device for an engine according to any one of the first to fifth inventions,
An exhaust gas recirculation device is further provided for sending exhaust gas to the upstream side of the electric assist turbocharger in the intake passage from the downstream side of the electric assist turbocharger in the exhaust passage.

  According to the condensate drainage device for an engine according to the first and sixth inventions, the condensate storage tank is configured by driving the electric assist turbocharger with electric power and opening the on-off valve to connect the bypass passage to the exhaust passage. The condensed water accumulated in the gas can be forcibly discharged to the exhaust passage by the supercharging pressure generated by driving the electric assist turbocharger.

  According to the condensate drainage device for an engine according to the second and sixth inventions, the condensate generated during vehicle travel can be drained after the key is turned off. It is possible to reliably prevent the passage from being blocked.

  According to the condensed water discharge device for an engine according to the third and sixth aspects of the invention, the condensed water generated during vehicle travel is discharged during deceleration, so that the condensed water can be discharged more reliably. In addition, since the amount discharged after the key is turned off is reduced, the time for the condensed water discharge control can be shortened. That is, it is effective to save the electric power required for driving the electrically assisted turbocharger.

  According to the condensed water discharge device for an engine according to the fourth and sixth inventions, since the condensed water discharge control is continued until the boost drop occurs, the condensed water is surely discharged, and the condensed water is stored in the condensed water storage tank. Condensed water can be prevented from remaining.

  According to the condensed water discharge device for an engine according to the fifth and sixth inventions, the supercharging pressure is easily increased by closing the throttle valve, so that the condensed water is discharged more reliably and smoothly.

It is the schematic of the internal combustion engine provided with the condensed water discharge apparatus of the engine which concerns on Example 1 of this invention. It is a flowchart explaining the action | operation of the condensed water discharge apparatus of the engine which concerns on Example 1 of this invention.

  Hereinafter, an engine condensate discharge device according to the present invention will be described with reference to the accompanying drawings.

  An engine condensed water discharger according to Embodiment 1 of the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic view of an internal combustion engine equipped with EGR. The internal combustion engine includes an intake passage 12, an exhaust passage 13, a catalyst 14, an engine 15, an electric assist turbocharger 21, an intercooler 22, a condensate storage tank 23, a bypass passage 24, an on-off valve 25, a high pressure EGR 27, and a high pressure throttle. A valve 28, a low-pressure EGR 30, a low-pressure throttle valve 31, a boost sensor 40, a vehicle speed sensor 41, and an ECU (Electronic Controlled Unit) 42 are provided.

  The electric assist turbocharger 21 described above uses the exhaust gas in the exhaust passage 13 to compress the air in the intake passage 12 to increase the charging efficiency. The intake passage 12 and the exhaust passage 13 are connected to each other. The compressor is provided on the intake passage 12 side and the turbine is provided on the exhaust passage 13 side (not shown). When the exhaust passage 13 is not exhausted or the exhaust is weak, the motor generator is driven to compress the air in the intake passage 12 and increase the charging efficiency. . In the case of a normal turbocharger, the supercharging pressure varies depending on the traveling state of the vehicle, but the electrically assisted turbocharger 21 can control the supercharging pressure without depending on the traveling state of the vehicle.

  The above-described intercooler 22 cools the intake air sent from the turbocharger 21 and further increases the charging efficiency, and is provided downstream of the turbocharger 21 in the intake passage 12.

  The condensate storage tank 23 described above stores condensate generated by intake air passing through the intercooler 22, and is provided downstream of the intercooler 22 in the intake passage 12.

  The bypass passage 24 described above communicates the condensed water storage tank 23 with the electric assist turbocharger 21 and the downstream side of the catalyst 14 in the exhaust passage 13 (the catalyst 14 is provided in the exhaust passage 13). It is a filter that purifies the exhaust gas component.

  The on-off valve 25 described above is a valve provided in the bypass passage 24 and can be opened and closed by the ECU 42.

  The high-pressure EGR 27 described above is an EGR that sends exhaust gas from between the engine 15 and the turbocharger 21 in the exhaust passage 13 into the intake passage 12 between the intercooler 22 and the engine 15. A high pressure EGR valve 29 for controlling the exhaust gas recirculation amount is provided at a portion where the high pressure EGR 27 joins with the intake passage 12. It arrange | positions so that it may be located in the downstream rather than.

  The high-pressure throttle valve 28 described above is a throttle valve that adjusts the amount of intake air, and is provided in the intake passage 12 on the downstream side of the condensed water storage tank 23.

  The low pressure EGR 30 is an EGR that sends exhaust gas from the downstream side of the electrically assisted turbocharger 21 and the catalyst 14 in the exhaust passage 13 to the upstream side of the electrically assisted turbocharger 21 in the intake passage 12. The low-pressure EGR 30 is provided with an EGR cooler 33 that cools air passing through the inside, and a low-pressure EGR valve 32 that controls the amount of exhaust gas recirculation is provided at a portion where it joins the intake passage 12.

  The above-described low-pressure throttle valve 31 is a throttle valve that adjusts the intake amount of intake air, and is provided upstream of the low-pressure EGR valve 32 in the intake passage 12.

  The above-described boost sensor 40 is a sensor that measures the supercharging pressure in the intake passage 12. However, if the high-pressure throttle valve 28 is completely closed, the boost pressure cannot be measured by the boost sensor 40.

  The ECU 42 opens and closes the electric assist turbocharger 21, the on-off valve 25, and the high-pressure throttle valve 28 when the supercharging pressure input from the boost sensor 40 and the acceleration / deceleration state of the vehicle satisfy predetermined conditions, and a condensed water storage tank. The condensed water accumulated in 23 is forcibly discharged downstream of the electrically assisted turbocharger 21 and the catalyst 14 in the exhaust passage 13 via the bypass passage 24. The acceleration / deceleration state of the vehicle is determined from the vehicle speed sensor 41 or the accelerator opening.

  Hereinafter, the operation of this apparatus will be described with reference to the flowchart shown in FIG.

  In step S1, the engine 15 is started. At this time, the on-off valve 25 is maintained in a closed state.

  In step S2, it is determined from the vehicle speed whether the vehicle is traveling. If the vehicle is running, the process proceeds to step S3. If the vehicle is stopped, the process proceeds to step S10.

  In step S3, the accelerator ON / OFF is detected from the accelerator opening, and it is determined whether or not the accelerator is OFF, that is, whether or not the vehicle is decelerating. If the accelerator is OFF and the vehicle is decelerating, the process proceeds to step S4. If not, the process proceeds to step S2.

  In step S4, it is confirmed that it is determined that the vehicle is traveling and is in a deceleration state.

  In step S5, condensed water discharge control is performed. That is, first, the high-pressure throttle valve 28 is closed, the on-off valve 25 is opened, and the electric assist turbocharger 21 is driven by electric power. As a result, the supercharging pressure in the intake passage 12 rises, and the condensed water accumulated in the condensed water storage tank 23 passes through the bypass passage 24 to the exhaust passage 13 by the supercharging pressure in the intake passage 12. Discharged.

  In step S5 described above, the high-pressure throttle valve 28 is closed and the on-off valve 25 is opened, and the electric assist turbocharger 21 is driven by electric power. However, the following steps S6 to S8 remain in this state. Assumed to be performed.

  In step S <b> 6, it is determined based on the boost pressure information in the intake passage 12 input from the boost sensor 40 whether or not the boost passage in the intake passage 12 has occurred. If it has not occurred, the process proceeds to step S7, and if it has occurred, the process proceeds to step S9. Here, the state in which the boost passage in the intake passage 12 has occurred means that all the condensed water accumulated in the condensed water storage tank 23 has been discharged through the bypass passage 24, so that the pressure in the intake passage 12 is increased. On the contrary, the state where the boost loss has not occurred indicates that the condensed water is still accumulated in the condensed water storage tank 23.

  In step S7, it is determined whether or not the vehicle is traveling. If the vehicle is running, the process proceeds to step S8, and if the vehicle is stopped, the process proceeds to step S9.

  In step S8, it is determined whether or not the vehicle is decelerating. If it is a deceleration state, it will return to step S6, and if it is an acceleration state, it will transfer to step S9.

  In step S9, the condensed water discharge control is stopped. That is, the high-pressure throttle valve 28 is opened, the driving of the electric assist turbocharger 21 with electric power is stopped, and the on-off valve 25 is closed.

  In steps S7 and S8, it is determined whether or not the vehicle is stopped or the vehicle has been decelerated before the boost passage in the intake passage 12 occurs. When the vehicle is stopped or when the vehicle changes from the deceleration state to the acceleration state (accelerator OFF to ON), the condensed water discharge control is stopped and the normal traveling state is restored. If the vehicle is running and the vehicle is decelerating, the condensate discharge control is continued until the boost loss occurs.

  Steps S3 to S9 are for performing condensed water discharge control when the vehicle is running and in a decelerating state. In addition, about the electric power used for the electric assist turbocharger 21, you may supply from a battery, and if it is a vehicle which can generate electric power at the time of deceleration, you may use the electric power generated at the time of deceleration.

  The reason for performing step S3 is that condensed water is discharged from the bypass passage 24 by controlling the supercharging pressure in the intake passage 12 in step S5, but this control is performed when the accelerator is depressed to accelerate. This is because the driver may feel uncomfortable, and it is preferable that the control be performed during deceleration when the accelerator is not depressed.

  Next, in step S10, it is determined whether or not the key is OFF. If the key is OFF, the process proceeds to step S11. If the key is not OFF, the process proceeds to step S2.

  In step S11, it is confirmed that it is determined that the vehicle is stopped and the key is OFF.

  In step S12, condensate discharge control is performed. Since this control is the same as step S5 described above, a description thereof will be omitted. The states of the high-pressure throttle valve 28, the electric assist turbocharger 21, and the on-off valve 25 controlled in step S12 are maintained in step S13.

  In step S13, it is determined whether or not the boost passage in the intake passage 12 has occurred. If it has occurred, the process proceeds to step S14. If not, step S13 is repeated.

  In step S14, the condensed water discharge control is stopped. Since this control is the same as step S9 described above, description thereof is omitted.

  Steps S <b> 10 to S <b> 14 are performed when the condensed water discharge control is performed when the vehicle is in a stopped state and the key is OFF, and the condensed water discharge control is stopped when the boost passage in the intake passage 12 occurs.

  In the present apparatus, the high-pressure throttle valve 28 is not an essential component. This is because the supercharging pressure in the intake passage 12 can be controlled by providing the electric assist turbocharger 21 without the high-pressure throttle valve 28. Therefore, control of the high pressure throttle valve 28 is not essential among the above steps.

  In the above, the condensed water discharge device for the engine according to the first embodiment has been described in detail. A condensate drain device for an engine comprising an electrically assisted turbocharger 21 and an intercooler 22 capable of controlling the supply pressure, and a condensate storage tank provided downstream of the intercooler 22 in the intake passage 12 23, a bypass passage 24 communicating with the condensed water storage tank 23 and the downstream side of the electrically assisted turbocharger 21 in the exhaust passage 13, an on-off valve 25 provided in the bypass passage 24, and driving of the electrically assisted turbocharger 21 And an ECU 42 (control means) for controlling the open / closed state of the open / close valve 25. Condensed water discharge control for forcibly discharging the condensed water stored in the condensed water storage tank 23 to the exhaust passage 13 through the bypass passage 24 by driving the strobe turbocharger 21 and opening the on-off valve 25 To do.

  As a result, the electrically assisted turbocharger 21 is driven by electric power and the on-off valve 25 is opened to connect the bypass passage 24 to the exhaust passage 13, so that the condensed water accumulated in the condensed water storage tank 23 can be removed from the electrically assisted turbocharger 21. Can be forcibly discharged to the exhaust passage 13 by the supercharging pressure generated by the driving of.

  Further, the ECU 42 performs the condensed water discharge control when it is determined that the vehicle is in a stopped state and the key is OFF.

  As a result, the condensed water generated when the vehicle travels can be discharged after the key is turned off, so that it is possible to reliably prevent the intake passage 12 from being blocked by the condensed water being frozen when the engine 15 is restarted. .

  Further, the ECU 42 performs the condensed water discharge control when it is determined that the vehicle is traveling and is in a decelerating state.

  Thereby, since the condensed water produced | generated at the time of vehicle travel is discharged | emitted at the time of deceleration, condensed water can be discharged | emitted more reliably. In addition, since the amount discharged after the key is turned off is reduced, the time for the condensed water discharge control can be shortened. That is, it is effective to save the electric power required for driving the electric assist turbocharger 21.

  Furthermore, the ECU 42 stops the condensed water discharge control when it is determined that the boost passage in the intake passage 12 has occurred.

  Thereby, the condensed water discharge control is stopped due to the occurrence of the boost loss (that is, the condensed water discharge control is continued until the boost loss occurs), so that the condensed water is reliably discharged, and the condensed water storage tank 23 Condensed water can be prevented from remaining inside.

  The apparatus includes a throttle valve (high-pressure throttle valve 28) provided downstream of the condensed water storage tank 23 in the intake passage 12, and the ECU 42 further increases the pressure during the condensed water discharge control. The throttle valve 28 may be controlled to be closed.

  As described above, since the supercharging pressure is easily increased by closing the throttle valve, the condensed water can be discharged more reliably and smoothly.

  In addition, this apparatus includes a low pressure EGR 30 that sends exhaust gas from the downstream side of the electric assist turbocharger 21 in the exhaust passage 13 to the upstream side of the electric assist turbocharger 21 in the intake passage 12.

  The present invention is suitable as a condensed water discharge device for an engine.

12 Intake passage 13 Exhaust passage 14 Catalyst (filter)
15 Engine 21 Electric assist turbocharger 22 Intercooler 23 Condensate storage tank 24 Bypass passage 25 On-off valve 27 High pressure EGR
28 High-pressure throttle valve 29 High-pressure EGR valve 30 Low-pressure EGR
31 Low pressure throttle valve 32 Low pressure EGR valve 33 EGR cooler 40 Boost sensor 41 Vehicle speed sensor 42 ECU

Claims (6)

This is a condensate drainage device for an engine comprising an electric assist turbocharger and an intercooler that can control the supercharging pressure in the intake passage without depending on the running state of the vehicle when the motor generator is driven. And
In the intake passage, a condensed water storage tank provided on the downstream side of the intercooler;
A bypass passage communicating the condensed water storage tank and the downstream side of the electrically assisted turbocharger in the exhaust passage;
An on-off valve provided in the bypass passage;
Control means for controlling the driving of the electric assist turbocharger and the open / close state of the on-off valve;
The control means forces the condensed water stored in the condensed water storage tank to the exhaust passage through a bypass passage by driving the electric assist turbocharger and opening the on-off valve under a predetermined condition. A condensed water discharge device for an engine, characterized in that the condensed water discharge control is performed to discharge automatically.   The condensate drain device for an engine according to claim 1, wherein the control means performs the condensate drain control when it is determined that the vehicle is stopped and the key is OFF.   3. The engine condensate discharge device according to claim 1, wherein the control unit performs the condensate discharge control when it is determined that the vehicle is running and in a decelerating state. 4.   The condensed water discharge device for an engine according to claim 1 or 2, wherein the control means stops the condensed water discharge control when it is determined that the boost passage in the intake passage has occurred. In the intake passage, provided with a throttle valve provided downstream of the condensed water storage tank,
5. The engine condensate discharge device according to claim 1, wherein the control unit further controls the throttle valve to be in a closed state during the condensate discharge control.   6. The exhaust gas recirculation device according to claim 1, further comprising an exhaust gas recirculation device that sends exhaust gas to the upstream side of the electric assist turbocharger in the intake passage from the downstream side of the electric assist turbocharger in the exhaust passage. The condensate drainage device for an engine according to any one of the preceding claims.

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