JP5770460B2 - EGR cooler condensate storage and discharge mechanism - Google Patents

Description

  The present invention relates to a mechanism for storing and discharging condensed water generated in an EGR cooler for cooling EGR gas recirculated from an engine exhaust passage to an intake passage through an EGR pipe.

  Conventionally, it has a gas passage through which exhaust gas from an internal combustion engine passes, and a liquid passage that is provided adjacent to the gas passage and through which cooling water passes, and has an inlet, an intermediate chamber, and an outlet through which the gas passage sequentially communicates. And the heat exchanger by which the lower part downstream of an intermediate | middle chamber is connected to the inlet port of an internal combustion engine through the tank which has a drain pipe is disclosed (for example, refer patent document 1). In the heat exchanger configured as described above, the condensed water generated in the heat exchanger is automatically removed from the heat exchanger and held in the tank because of the low pressure generated in the intake port. Here, the condensed water is retained in the tank because the pressure in the tank is slightly lower than the atmospheric pressure. As a result, the inside of the heat exchanger is not corroded by acidic substances, and the life of the heat exchanger can be extended. Further, the condensed water held in the tank is automatically and quietly discharged because the inside of the tank is opened to the atmosphere after the internal combustion engine is stopped.

  On the other hand, the exhaust passage and the section upstream of the compressor of the intake passage are connected by an EGR passage, and in this EGR passage, a collecting portion for collecting condensed water, and a storage portion for storing the collected condensed water And an exhaust gas recirculation apparatus in which a storage unit is connected to a discharge unit for discharging condensed water is disclosed (for example, see Patent Document 2). In this exhaust gas recirculation device, the pressure in the section downstream of the compressor in the intake passage is introduced from the pressure introduction path to the storage section, and this pressure introduction path is configured to be opened and closed by an on-off valve. In addition, a reverse valve is provided between the collection unit and the storage unit to allow the flow from the collection unit to the storage unit while preventing the flow from the storage unit to the collection unit, and the discharge path is a discharge valve. Is configured to be opened and closed. The EGR passage is provided with an EGR cooler that cools the EGR gas, and the collection portion is disposed downstream of the EGR cooler with respect to the flow direction of the EGR gas. Further, an intercooler that cools the intake air pressurized by the compressor is provided in the intake passage, and the pressure introduction path is connected to the intake passage between the compressor and the intercooler.

  In the exhaust gas recirculation apparatus configured as described above, when the pressure introduction path is closed by the on-off valve, the condensed water collected in the collection section is stored in the storage section through the check valve, and the pressure introduction path is opened. The intake air pressure downstream of the compressor is introduced from the pressure introduction path into the storage part, and condensed water is discharged from the storage part at that pressure, while a check valve is provided between the storage part and the collection part. Closed. As a result, the condensed water generated in the EGR passage can be discharged while suppressing the backflow to the EGR passage. Also, while condensate is stored in the reservoir, closing the drain valve and closing the reservoir from the outside can suppress the leakage of gas components from the collector to the reservoir and keep the internal pressure of the reservoir low. By doing so, the check valve is easily opened by the weight of the condensed water, so that the condensed water can move from the collecting section to the storing section.

Japanese Utility Model Publication No. 61-144374 (Claim 1, specification, page 7, line 11 to page 12, line 12, specification, page 8, line 15 to page 19, line 19, specification, page 9, line 2) Line to 4th line of the same page, FIG. 1 and FIG. 3) JP 2008-280945 A (claims 1 to 3, paragraph [0009], FIG. 1)

  However, in the heat exchanger shown in the above-mentioned conventional Patent Document 1, since this heat exchanger is provided extending in the horizontal direction, the condensed water generated in the heat exchanger remains in the heat exchanger, There is a problem that it is difficult to be stored in the tank, and because the condensed water in the tank is discharged by its own weight by opening the tank to the atmosphere, it takes a relatively long time to discharge the condensed water from the tank. There was also.

  On the other hand, in the exhaust gas recirculation device disclosed in the above-mentioned conventional patent document 2, since the condensed water in the reservoir is discharged using the pressure of the compressor, the compressor pressure is extremely low when the engine is stopped without any compressor pressure. When idling the engine, there was a problem that the condensed water in the reservoir could not be discharged. Further, the exhaust gas recirculation apparatus disclosed in the above-mentioned conventional patent document 2 can be applied to an engine with a turbocharger, but has a problem that it cannot be applied to a naturally aspirated engine. Furthermore, in the exhaust gas recirculation device shown in the above-mentioned conventional patent document 2, there is a possibility that the condensed water generated in the EGR cooler may flow into the engine. there were.

  A first object of the present invention is an EGR cooler that can quickly store condensed water generated in the EGR cooler in the drain mechanism, and can quickly discharge the condensed water stored in the drain mechanism when the engine is stopped or idling. It is to provide a storage and discharge mechanism for condensed water. The second object of the present invention can be applied not only to a turbocharged engine but also to a naturally aspirated engine, and it is possible to separate condensed water from EGR gas without providing a collection part having a relatively complicated structure. It is in providing the storage and discharge mechanism of the condensed water of an EGR cooler. The third object of the present invention is to store the condensed water in the EGR cooler, which can effectively use the EGR regulating valve to quickly discharge the condensed water stored in the drain mechanism and can prevent the engine from being corroded by the condensed water. And providing a discharge mechanism. A fourth object of the present invention is to provide an EGR cooler condensate water storage and discharge mechanism in which a drain pressure increasing valve and an EGR adjustment valve used for discharging condensate water can be configured with relatively inexpensive parts that do not require heat resistance. It is to provide.

  As shown in FIG. 1, the first aspect of the present invention is provided with an EGR pipe 14 that connects the exhaust passage 12 and the intake passage 13 of the engine 11, and passes through the EGR pipe 14 from the exhaust passage 12 to the intake passage 13. The EGR gas is recirculated, and the EGR pipe 14 is provided with a first EGR cooler 21 and a second EGR cooler 22 in order from the exhaust passage 12 to the intake passage 13, and an EGR adjustment for adjusting the flow rate of the EGR gas flowing through the EGR pipe 14. An engine EGR device in which a valve 16 is provided in an EGR pipe 14 and first and second EGR coolers 21 and 22 are configured to cool EGR gas of 100 ° C. or higher in two stages to cool to less than 100 ° C. The at least second EGR cooler 22 is provided on the side of the engine 11 and extends in the vertical direction, and the EGR gas is supplied to the second EG. The second EGR cooler 22 or the first and second EGR coolers 21 are connected to the EGR pipe 14 connected to the lower end of the second EGR cooler 22 so as to flow into the cooler 22 from the lower end or upper end thereof and to be discharged from the upper end or lower end thereof. , 22 is connected to a drain mechanism 17 that stores and discharges the condensed water 28 generated at a position lower than the horizontal plane including the lower end of the second EGR cooler 22, the drain pressure increasing valve 18 that opens and closes the EGR pipe 14, and the EGR adjustment valve 16. Is disposed so as to sandwich a connection portion of the drain mechanism 17 to the EGR pipe 14, and compressed air supply means 19 for supplying compressed air to the EGR pipe 14 between the drain pressure increasing valve 18 and the EGR adjustment valve 16 is connected. The controller 26 controls the EGR adjusting valve 16, the drain pressure increasing valve 18, the compressed air supply means 19 and the drain according to the operating condition of the engine 11. Characterized in that it is configured to control the mechanism 17.

A second aspect of the present invention is an invention based on the first aspect, and further, as shown in FIG. 1, the first EGR cooler 21 is on the side of the engine 11 and below the exhaust manifold 12a in the exhaust passage 12. The second EGR cooler 22 is provided on the side of the engine 11 and below the intake manifold 13a of the intake passage 13 and extends in the vertical direction. The first EGR cooler 21 The upper end of the second EGR cooler 22 is connected directly to the intake manifold 13a, or the upper end of the second EGR cooler 22 is connected directly to the exhaust manifold 12a. The EGR pipe 14 is connected via a second communication pipe 14 b that constitutes a part of the EGR pipe 14, and the lower end of the first EGR cooler 21 is connected to the lower end of the second EGR cooler 22. The drain mechanism 17 is provided at a position lower than the horizontal plane including the lower surface of the engine 11, and the drain pressure increasing valve 18 is connected to the first EGR cooler 21 and the drain mechanism 17. The EGR adjustment valve 16 is provided between the connection portion of the drain mechanism 17 to the third communication tube 14c and the second EGR cooler 22 between the connection portion to the third communication tube 14c. It is provided in the third communication pipe 14c.

The third aspect of the present invention is an invention based on the first aspect, and as shown in FIG. 2, the first EGR cooler 21 is located above the engine 11 and extends in the horizontal direction. The 2EGR cooler 22 is provided on the side of the engine 11 and extends in the vertical direction, and one end of the first EGR cooler 21 forms a part of the EGR pipe 54 in the exhaust manifold 12a of the exhaust passage 12. The upper end of the second EGR cooler 22 is connected to the other end of the first EGR cooler 21 via a second communication pipe 54b that forms part of the EGR pipe 54, and the lower end of the second EGR cooler 22 is connected to the intake passage. 13 is connected to the intake manifold 13a via a third communication pipe 54c constituting a part of the EGR pipe 54, and the drain mechanism 17 is lower than a horizontal plane including the lower surface of the engine 11. Provided in a position, drainage booster valve 18 provided in the third communicating tube 54c between the connection to the third communication pipe 54c of the 2EGR cooler 22 and the drain mechanism 17, EGR control valve 16 is the drain mechanism 17 It is provided in the third communication pipe 54c between the connection portion to the third communication pipe 54c and the intake manifold 13a.

  A fourth aspect of the present invention is an invention based on the second or third aspect, and as shown in FIG. 1, the drain mechanism 17 is connected to the third communication pipe 14c and extends downward. 17a, a drain tank 17b provided in the middle of the drain pipe 17a, and a drain valve 17c provided in the drain pipe 17a below the drain tank 17b for opening and closing the drain pipe 17a.

  In the EGR cooler condensate water storage and discharge mechanism according to the first aspect of the present invention, when the controller opens the EGR adjustment valve at a predetermined opening during engine operation, a part of the exhaust gas in the exhaust passage is EGR gas. And then returned to the intake passage through the EGR pipe. At this time, the condensed water generated in the second EGR cooler or the like flows down the second EGR cooler or the like provided in the vertical direction, and is stored in the drain mechanism through the EGR pipe connected to the lower end of the second EGR cooler. As a result, the condensed water generated by the second EGR cooler or the like can be quickly stored in the drain mechanism. Further, since the controller controls the EGR adjustment valve, the drain pressure increasing valve, the compressed air supply means and the drain mechanism according to the operating state of the engine, when the engine is stopped or in an idling state, the controller By closing the drain pressure increasing valve and opening the compressed air supply means and the drain mechanism, the condensed water stored in the drain mechanism can be quickly discharged. At this time, the EGR adjustment valve that adjusts the flow rate of the EGR gas that normally flows through the EGR pipe is used to quickly discharge the condensed water stored in the drain mechanism, so that the EGR adjustment valve can be effectively used. Furthermore, since the condensed water in the reservoir is discharged using the pressure of the turbocharger compressor, it can be applied to engines with turbochargers, but it cannot be applied to naturally aspirated engines. Thus, the present invention can be applied not only to a turbocharged engine but also to a naturally aspirated engine.

  In the condensate water storage and discharge mechanism of the EGR cooler according to the second aspect of the present invention, since the drain mechanism is provided at a position lower than the horizontal plane including the lower surface of the engine, the condensate water stored in the drain mechanism is discharged. , Condensate is not applied to the engine, and the engine will not get wet with the condensate. As a result, engine corrosion due to condensed water can be prevented. Further, since condensed water generated in the EGR cooler may flow into the engine, in the present invention, EGR gas is contained in the second EGR as compared with a conventional exhaust gas recirculation device that requires a relatively complicated collection part. While the cooler is raised and flows into the intake manifold, the condensed water generated in the second EGR cooler descends the second EGR cooler and flows into the drain mechanism due to its own weight. Without providing, the condensed water can be separated from the EGR gas.

In the condensate water storage and discharge mechanism of the EGR cooler according to the third aspect of the present invention, since the drain mechanism is provided at a position lower than the horizontal plane including the lower surface of the engine, the condensate water stored in the drain mechanism is the same as described above. When the engine is discharged, no condensate is applied to the engine, and the engine does not get wet with the condensate. As a result, engine corrosion due to condensed water can be prevented. Also, since the drain pressure increasing valve and the EGR regulating valve are provided in the third communication pipe through which the EGR gas that has passed the second EGR cooler and has become less than 100 ° C., the drain pressure increasing valve and the EGR regulating valve have heat resistance components. There is no need to configure. As a result, since the drain pressure increasing valve and the EGR regulating valve can be configured with relatively inexpensive parts that do not require heat resistance, the manufacturing cost can be reduced. Further, since the condensed water generated in the EGR cooler may flow into the engine, compared with a conventional exhaust gas recirculation device that requires a relatively complicated structure, the EGR gas and the condensed water are used in the present invention. After the lowering of the second EGR cooler, the EGR gas rises from the connection part to the third communication pipe of the drain mechanism to the third communication pipe on the intake manifold side, but the condensed water is connected to the third communication pipe of the drain mechanism . Therefore, the condensed water can be separated from the EGR gas without providing a collecting part having a relatively complicated structure.

  In the EGR cooler condensed water storage and discharge mechanism according to the fourth aspect of the present invention, when the drain pressure increasing valve and the EGR regulating valve are opened and the drain valve is closed, the condensed water generated in the second EGR cooler and the like is passed through the drain pipe. Passed through and stored in the drain tank. When the compressed air is supplied to the third communication pipe of the EGR pipe by the compressed air supply means with the drain pressure increasing valve and the EGR regulating valve closed and the drain valve opened, the condensed water in the drain tank passes through the drain pipe. Discharged. As a result, the condensed water in the drain tank can be quickly discharged.

It is a block diagram of the intake / exhaust system of an engine including the storage and discharge mechanism of the condensed water of the EGR cooler of 1st Embodiment of this invention. It is a block diagram of the intake / exhaust system of an engine including the storage and discharge mechanism of the condensed water of the EGR cooler of 2nd Embodiment of this invention.

Next, an embodiment for carrying out the present invention will be described with reference to the drawings.
<First Embodiment>
As shown in FIG. 1, the EGR device includes an EGR pipe 14 that connects an exhaust passage 12 and an intake passage 13 of a naturally aspirated diesel engine 11 and recirculates EGR gas from the exhaust passage 12 to the intake passage 13. The first and second EGR coolers 21 and 22 that cool the EGR gas that is provided in the EGR pipe 14 and flows through the EGR pipe 14, and the EGR adjustment valve 16 that is provided in the EGR pipe 14 and adjusts the flow rate of the EGR gas that flows through the EGR pipe 14. With. The exhaust passage 12 has an exhaust manifold 12 a having one end connected to the exhaust port of the diesel engine 11 and an exhaust pipe 12 b connected to the other end of the exhaust manifold 12 a. The intake manifold 13a has one end connected to the intake port, and the intake pipe 13b connected to the other end of the intake manifold 13a. In this embodiment, the EGR pipe 14 has one end connected to the exhaust manifold 12a and the other end connected to the intake manifold 13a. The EGR device and the diesel engine 11 are mounted on a truck (not shown) in this embodiment.

  The first EGR cooler 21 and the second EGR cooler 22 are provided in this order from the exhaust manifold 12a toward the intake manifold 13a. In this embodiment, the first EGR cooler 21 is provided on the side of the engine 11 and below the exhaust manifold 12a and extends in the vertical direction, and the second EGR cooler 22 is on the side of the engine 11 and intake air. It is located below the manifold 13a and extends in the vertical direction. The upper end of the first EGR cooler 21 is connected to the exhaust manifold 12a via a first communication pipe 14a constituting a part of the EGR pipe 14, and the upper end of the second EGR cooler 22 is connected to the intake manifold 13a and a part of the EGR pipe 14. The lower end of the first EGR cooler 21 is connected to the lower end of the second EGR cooler 22 via a third communication pipe 14c constituting a part of the EGR pipe 14. The first and second communication pipes 14 a and 14 b are formed in a straight line extending in the vertical direction, and the third communication pipe 14 c is formed in a substantially U shape so as to face the bottom surface and both lower side surfaces of the engine 11. Thus, the EGR gas is configured to flow into the second EGR cooler 22 from its lower end and to be discharged from its upper end. In the first embodiment, the upper end of the first EGR cooler is connected to the exhaust manifold via the first communication pipe, and the upper end of the second EGR cooler is connected to the intake manifold via the second communication pipe. The upper end of the first EGR cooler may be directly connected to the exhaust manifold without going through the first communication pipe, and the upper end of the second EGR cooler may be directly connected to the intake manifold without going through the second communication pipe.

  The first EGR cooler 21 is a water-cooled EGR cooler that is cooled by cooling water of a radiator (not shown) that cools the engine 11, and the second EGR cooler 22 is cooling water of a dedicated heat exchanger (not shown). It is preferable that it is a water-cooled EGR cooler cooled by. The first and second EGR coolers 21 and 22 are preferably formed in the same shape. In this embodiment, the first and second EGR coolers 21 and 22 are each formed in a substantially lotus-like multi-tube type (tube type). Specifically, although not shown, the first and second EGR coolers 21 and 22 are provided so as to extend in the vertical direction and are arranged to gather at a predetermined interval in the horizontal direction so that EGR gas flows therethrough. And a cooler case that extends in the vertical direction, accommodates a plurality of tubes, allows cooling water to circulate, and indirectly contacts the cooling water with the EGR gas in the tube. The first and second EGR coolers 21 and 22 are configured so that EGR gas of 100 ° C. or higher is cooled to less than 100 ° C. in two stages.

  On the other hand, the drain mechanism 17 is connected to the EGR pipe 14 connected to the lower end of the second EGR cooler 22, that is, the third communication pipe 14 c connecting the lower end of the first EGR cooler 21 and the lower end of the second EGR cooler 22. Are provided at a position lower than the horizontal plane including the lower end of the engine 11 and at a position lower than the horizontal plane including the lower surface of the engine 11. The drain mechanism 17 is provided in a drain pipe 17a connected to the third communication pipe 14c and extending downward, a drain tank 17b provided in the middle of the drain pipe 17a, and a drain pipe 17a below the drain tank 17b. And a drain valve 17c for opening and closing the drain pipe 17a. Further, the third communication pipe 14c of the EGR pipe 14 is provided with a drain pressure increasing valve 18 that opens and closes the third communication pipe 14c. The drain pressure increasing valve 18 and the EGR adjustment valve 16 are arranged so that the connection portion of the drain pipe 17a to the third communication pipe 14c is sandwiched between these valves 18 and 16. That is, the drain pressure increasing valve 18 is provided in the third communication pipe 14c between the lower end of the first EGR cooler 21 and the connection portion of the drain pipe 17a to the third communication pipe 14c, and the EGR adjustment valve 16 is provided in the first pipe of the drain pipe 17a. It is provided in the third communication pipe 14 c between the connection portion to the three communication pipes 14 c and the lower end of the second EGR cooler 22.

  On the other hand, the EGR pipe 14 between the drain pressure increasing valve 18 and the EGR adjustment valve 16, that is, the third communication pipe 14c between the drain pressure increasing valve 18 and the EGR adjustment valve 16, is compressed air into the third communication pipe 14c. Compressed air supply means 19 is connected. The compressed air supply means 19 includes an air tank 19a that stores compressed air, an air pipe 19b that connects the air tank 19a and the third communication pipe 14c, and an air pipe 19b that opens and closes the air pipe 19b. And an air on-off valve 19c. 1 is a rotation sensor that detects the rotation speed of the engine 11, and 24 is a load sensor that detects the load of the engine 11. The detection outputs of the rotation sensor 23 and the load sensor 24 are connected to the control input of the controller 26, and the control output of the controller 26 is connected to the EGR adjustment valve 16, the drain pressure increasing valve 18, the air on-off valve 19c and the drain valve 17c, respectively. . Further, a memory 27 is connected to the controller 26. In this memory 27, the opening degree of the EGR adjustment valve 16 corresponding to the rotational speed and load of the engine 11 is stored as a map.

  The operation of the storage and discharge mechanism of the condensed water 28 of the EGR coolers 21 and 22 configured as described above will be described. When the rotation sensor 23 and the load sensor 24 detect medium / high-speed rotation and medium / high load of the engine 11, the controller 26 opens the EGR adjustment valve 16 at a predetermined opening according to the rotation speed and load of the engine 11. The drain pressure increasing valve 18, the air on-off valve 19c and the drain valve 17c are kept closed. As a result, EGR gas, which is part of the exhaust gas, recirculates from the exhaust manifold 12a to the intake manifold 13a through the first communication pipe 14a, the first EGR cooler 21, the third communication pipe 14c, the second EGR cooler 22, and the second communication pipe 14b. Is done. Specifically, EGR gas having a temperature exceeding 100 ° C. (for example, about 600 ° C.) is cooled by the first EGR cooler 21 and is lower than the temperature before flowing into the first EGR cooler 21 but still exceeding 100 ° C. For example, the EGR gas is 150 ° C., and the EGR gas still having a temperature exceeding 100 ° C. (for example, 150 ° C.) is cooled by the second EGR cooler 22, and the EGR gas having a temperature of less than 100 ° C. (for example, 50 ° C.). Then, it is returned to the intake manifold 13a. At this time, when the EGR gas passes through the second EGR cooler 22 and is cooled to a temperature higher than 100 ° C. (for example, 150 ° C.) to a temperature lower than 100 ° C. (for example, 50 ° C.), it was included in the EGR gas. Water vapor is condensed and condensed water 28 is generated. The condensed water 28 flows down due to its own weight in the tube of the second EGR cooler 22 extending in the vertical direction, and is stored in the drain tank 17b through the third communication pipe 14c and the drain pipe 17a.

  When the rotation sensor 23 and the load sensor 24 detect the low-speed rotation and the low load of the engine 11, respectively, the controller 26 sets the EGR adjustment valve 16 at a predetermined opening narrower than the opening according to the rotation speed and the load of the engine 11. While being opened, the drain pressure increasing valve 18, the air on-off valve 19c and the drain valve 17c are kept closed. As a result, the EGR gas having a temperature exceeding 100 ° C. (for example, about 600 ° C.) is cooled by the first EGR cooler 21 to become an EGR gas having a temperature lower than 100 ° C. (for example, 90 ° C.). For example, the EGR gas at 90 ° C. is cooled by the second EGR cooler 22, becomes EGR gas at a lower temperature (for example, 50 ° C.), and is recirculated to the intake manifold 13 a. At this time, if the EGR gas passes through the first EGR cooler 21 and is cooled to a temperature higher than 100 ° C. (for example, about 600 ° C.) to a temperature lower than 100 ° C. (for example, 90 ° C.), it is contained in the EGR gas. The condensed water vapor is condensed to generate condensed water 28. The condensed water 28 flows down in the tube of the first EGR cooler 21 extending in the vertical direction by its own weight, and is stored in the drain tank 17b through the third communication pipe 14c and the drain pipe 17a. Further, when the EGR gas passes through the second EGR cooler 22 and is cooled to a temperature lower than 100 ° C. (for example, 50 ° C.) from a temperature lower than 100 ° C. (for example, 90 ° C.), it is contained in the EGR gas. The condensed water vapor is condensed to generate condensed water 28. The condensed water 28 flows down due to its own weight in the tube of the second EGR cooler 22 extending in the vertical direction, and is stored in the drain tank 17b through the third communication pipe 14c and the drain pipe 17a.

  Further, when the rotation sensor 23 and the load sensor 24 detect low-speed rotation and no load of the engine 11 respectively, the controller 26 determines that the engine 11 is idling, closes the EGR adjustment valve 16, drains the pressure increase valve 18, air The on-off valve 19c and the drain valve 17c are kept closed. Thereby, the flow of EGR gas in the EGR pipe 14 is stopped. Immediately after the flow of the EGR gas is stopped, the EGR gas in the first EGR cooler 21 is cooled by the first EGR cooler 21, and the water vapor contained in the EGR gas is condensed to generate condensed water 28. The condensed water 28 flows down in the tube of the first EGR cooler 21 extending in the vertical direction by its own weight, and is stored in the drain tank 17b through the third communication pipe 14c and the drain pipe 17a. Further, immediately after the EGR gas flow is stopped, the EGR gas in the second EGR cooler 22 is cooled by the second EGR cooler 22, and the water vapor contained in the EGR gas is condensed to generate condensed water 28. The condensed water 28 flows down due to its own weight in the tube of the second EGR cooler 22 extending in the vertical direction, and is stored in the drain tank 17b through the third communication pipe 14c and the drain pipe 17a. Thus, the condensed water 28 generated in the second EGR cooler 22 or the first and second EGR coolers 21 and 22 is separated from the EGR gas and quickly stored in the drain tank 17b.

  On the other hand, when the truck is stopped at a predetermined position in the parking lot and the key switch of the driver's seat is turned off, the rotation sensor 23 detects that the rotational speed of the engine 11 has become zero, so that the controller 26 After determining that it has stopped and closing the EGR adjustment valve 16 and the drain pressure increasing valve 18, the drain valve 17c is opened and the air on-off valve 19c is opened. By closing the EGR adjustment valve 16, the drain mechanism 17 and the compressed air supply means 19 are disconnected from the second EGR cooler 22 and the intake manifold 13 a, and the drain pressure increasing valve 18 is closed to close the drain mechanism 17 and the compressed air supply means 19. The communication with the first EGR cooler 21 and the exhaust manifold 12a is blocked. Further, by opening the drain valve 17c and the air opening / closing valve 19c, the compressed air in the air tank 19a flows into the drain tank 17b through the air pipe 19b, the third communication pipe 14c and the upper drain pipe 17a. The internal pressure rises, and the condensed water 28 in the drain tank 17b is discharged outside the vehicle through the lower drain pipe 17a. As a result, the condensed water 28 stored in the drain tank 17b can be quickly discharged. At this time, the EGR adjustment valve 16 that adjusts the flow rate of the EGR gas that normally flows through the EGR pipe 14 is used for quickly discharging the condensed water 28 stored in the drain tank 17b, and effective use of the EGR adjustment valve 16 is achieved. Can be planned. Further, since the drain mechanism 17 is provided at a position lower than the horizontal plane including the lower surface of the engine 11, the condensed water 28 is not applied to the engine 11 when the condensed water 28 stored in the drain tank 17b is discharged, and the engine 11 is condensed. It does not get wet with water 28. As a result, corrosion of the engine 11 due to the condensed water 28 can be prevented.

<Second Embodiment>
FIG. 2 shows a second embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 denote the same components. In this embodiment, the first EGR cooler 21 is located above the engine 11 and extends in the horizontal direction, and the second EGR cooler 22 is located on the side of the engine 11 and extends in the vertical direction. One end of the first EGR cooler 21 is connected to the exhaust manifold 12 a via a first communication pipe 54 a constituting a part of the EGR pipe 54, and the upper end of the second EGR cooler 22 is connected to the other end of the first EGR cooler 21. The second EGR cooler 22 is connected to the intake manifold 13a via a third communication pipe 54c that constitutes a part of the EGR pipe 54. The first communication tube 54a is formed in an approximately inverted L shape, the second communication tube 54b is formed in an approximately inverted J shape, and the third communication tube 54c is formed in an approximately J shape that is reversed left and right.

  On the other hand, the drain mechanism 17 connects the lower end of the second EGR cooler 22 to the EGR pipe 54 connected to the lower end of the second EGR cooler 22, that is, the third communication pipe 54c connecting the lower end of the second EGR cooler 22 and the intake manifold 13a. It is connected at a position lower than the horizontal plane including it, and is provided at a position lower than the horizontal plane including the lower surface of the engine 11. The third communication pipe 54c is provided with a drain pressure increasing valve 18 that opens and closes the third communication pipe 54c. The drain pressure increasing valve 18 and the EGR adjustment valve 16 are arranged so that the connection portion of the drain pipe 17a to the third communication pipe 54c is sandwiched between these valves 18 and 16. That is, the drain pressure increasing valve 18 is provided in the third communication pipe 54c between the lower end of the second EGR cooler 22 and the connection portion of the drain pipe 17a to the third communication pipe 54c, and the EGR adjustment valve 16 is provided in the first pipe of the drain pipe 17a. It is provided in the third communication pipe 54c between the connection portion to the three communication pipe 54c and the intake manifold 13a. The configuration other than the above is the same as that of the first embodiment.

  The operation of the storage and discharge mechanism of the condensed water 28 of the EGR coolers 21 and 22 configured as described above will be described. When the rotation sensor 23 and the load sensor 24 detect medium / high-speed rotation and medium / high load of the engine 11, the controller 26 opens the EGR adjustment valve 16 at a predetermined opening according to the rotation speed and load of the engine 11. The drain pressure increasing valve 18, the air on-off valve 19c and the drain valve 17c are kept closed. As a result, EGR gas, which is part of the exhaust gas, recirculates from the exhaust manifold 12a to the intake manifold 13a through the first communication pipe 54a, the first EGR cooler 21, the second communication pipe 54b, the second EGR cooler 22, and the third communication pipe 54c. Is done. Specifically, EGR gas having a temperature exceeding 100 ° C. (for example, about 600 ° C.) is cooled by the first EGR cooler 21 and is lower than the temperature before flowing into the first EGR cooler 21 but still exceeding 100 ° C. For example, the EGR gas is 150 ° C., and the EGR gas still having a temperature exceeding 100 ° C. (for example, 150 ° C.) is cooled by the second EGR cooler 22, and the EGR gas having a temperature of less than 100 ° C. (for example, 50 ° C.). Then, it is returned to the intake manifold 13a. At this time, when the EGR gas passes through the second EGR cooler 22 and is cooled to a temperature higher than 100 ° C. (for example, 150 ° C.) to a temperature lower than 100 ° C. (for example, 50 ° C.), it was included in the EGR gas. Water vapor is condensed and condensed water 28 is generated. The condensed water 28 flows down due to its own weight in the tube of the second EGR cooler 22 extending in the vertical direction, and is stored in the drain tank 17b through the third communication pipe 54c and the drain pipe 17a.

  When the rotation sensor 23 and the load sensor 24 detect the low-speed rotation and the low load of the engine 11, respectively, the controller 26 sets the EGR adjustment valve 16 at a predetermined opening narrower than the opening according to the rotation speed and the load of the engine 11. While being opened, the drain pressure increasing valve 18, the air on-off valve 19c and the drain valve 17c are kept closed. As a result, the EGR gas having a temperature exceeding 100 ° C. (for example, about 600 ° C.) is cooled by the first EGR cooler 21 to become an EGR gas having a temperature lower than 100 ° C. (for example, 90 ° C.). For example, the EGR gas at 90 ° C. is cooled by the second EGR cooler 22, becomes EGR gas at a lower temperature (for example, 50 ° C.), and is recirculated to the intake manifold 13 a. At this time, if the EGR gas passes through the first EGR cooler 21 and is cooled to a temperature higher than 100 ° C. (for example, about 600 ° C.) to a temperature lower than 100 ° C. (for example, 90 ° C.), it is contained in the EGR gas. The condensed water vapor is condensed to generate condensed water 28. This condensed water 28 is stored in the drain tank 17b through the second communication pipe 54b, the second EGR cooler 22, the third communication pipe 54c and the drain pipe 17a by the flow of EGR gas in the tube of the first EGR cooler 21 extending in the horizontal direction. Is done. Further, when the EGR gas passes through the second EGR cooler 22 and is cooled to a temperature lower than 100 ° C. (for example, 50 ° C.) from a temperature lower than 100 ° C. (for example, 90 ° C.), it is contained in the EGR gas. The condensed water vapor is condensed to generate condensed water 28. The condensed water 28 flows down due to its own weight in the tube of the second EGR cooler 22 extending in the vertical direction, and is stored in the drain tank 17b through the third communication pipe 54c and the drain pipe 17a.

  Further, when the rotation sensor 23 and the load sensor 24 detect the low speed rotation and no load of the engine 11, respectively, the controller 26 determines that the engine 11 is idling, so the EGR adjustment valve 16 is closed and the drain pressure increasing valve 18, The air on-off valve 19c and the drain valve 17c are kept closed. As a result, the flow of EGR gas in the EGR pipe 54 is stopped. Immediately after the flow of the EGR gas is stopped, the EGR gas in the first EGR cooler 21 is cooled by the first EGR cooler 21, and the water vapor contained in the EGR gas is condensed to generate condensed water 28. This condensed water 28 is stored in the drain tank 17b through the second communication pipe 54b, the second EGR cooler 22, the third communication pipe 54c and the drain pipe 17a by the flow of EGR gas in the tube of the first EGR cooler 21 extending in the horizontal direction. Is done. Further, immediately after the EGR gas flow is stopped, the EGR gas in the second EGR cooler 22 is cooled by the second EGR cooler 22, and the water vapor contained in the EGR gas is condensed to generate condensed water 28. The condensed water 28 flows down due to its own weight in the tube of the second EGR cooler 22 extending in the vertical direction, and is stored in the drain tank 17b through the third communication pipe 54c and the drain pipe 17a. Thus, the condensed water 28 generated in the second EGR cooler 22 or the first and second EGR coolers 21 and 22 is separated from the EGR gas and quickly stored in the drain tank 17b.

  On the other hand, since the drain pressure increasing valve 18 and the EGR regulating valve 16 are provided in the third communication pipe 54c through which the EGR gas that has passed the second EGR cooler 22 and has become less than 100 ° C. passes, the drain pressure increasing valve 18 and the EGR regulating valve. It is not necessary to configure 16 with heat-resistant parts. As a result, since the drain pressure increasing valve 18 and the EGR regulating valve 16 can be configured with relatively inexpensive parts that do not require heat resistance, the manufacturing cost can be reduced. Since the operation other than the above is substantially the same as the operation of the first embodiment, repeated description will be omitted.

  In the first and second embodiments, the first and second EGR coolers are formed in a substantially lotus-like multi-tube type (tube type), respectively. However, the first and second EGR coolers are formed in a stacked type, respectively. May be. The stacked EGR cooler is provided extending in the vertical direction and stacked in a horizontal direction with a predetermined interval, and a plurality of flat tubes through which EGR gas flows, and extending in the vertical direction, and accommodates the plurality of tubes. And a cooler case in which the cooling water flows and indirectly makes contact with the EGR gas in the tube. In the first and second embodiments, the condensate stored in the drain tank is controlled to be discharged when the engine is stopped. However, the condensate stored in the drain tank is discharged when the engine is idling. You may control to discharge | emit.

  In the first and second embodiments, the condensate storage and discharge mechanism of the EGR cooler of the present invention is applied to a naturally aspirated diesel engine. However, a diesel engine with a turbocharger, The present invention may be applied to an intake type gasoline engine or a gasoline engine with a turbocharger. Here, when the condensate water storage and discharge mechanism of the EGR cooler of the present invention is applied to a diesel engine with a turbocharger or a gasoline engine with a turbocharger, the hot EGR gas is supercooled, Even if a relatively large amount of condensed water is generated in the 2EGR cooler or the first and second EGR coolers, the condensed water can be quickly separated from the EGR gas, and the fuel efficiency performance and exhaust gas purification performance of the engine can be improved. Furthermore, in the first and second embodiments, the EGR device and the engine are mounted on the truck. However, the EGR device and the engine may be mounted on a passenger car, an industrial machine, or the like.

11 Diesel engine (engine)
12 Exhaust passage 12a Exhaust manifold 13 Intake passage 13a Intake manifold 14, 54 EGR pipes 14a, 54a First communication pipe 14b, 54b Second communication pipe 14c, 54c Third communication pipe 16 EGR adjustment valve 17 Drain mechanism 17a Drain pipe 17b Drain Tank 17c Drain valve 18 Drain pressure increasing valve 19 Compressed air supply means 21 First EGR cooler 22 Second EGR cooler 26 Controller 28 Condensed water

Claims (4)

An EGR pipe (14, 54) connecting the exhaust passage (12) of the engine (11) and the intake passage (13) is provided, and passes through the EGR pipe (14, 54) from the exhaust passage (12). The EGR gas is recirculated to the intake passage (13), and the first EGR cooler (21) and the second EGR cooler (22) are sequentially supplied to the EGR pipe (14, 54) from the exhaust passage (12) toward the intake passage (13). ) And an EGR adjustment valve (16) for adjusting the flow rate of the EGR gas flowing through the EGR pipe (14, 54) is provided in the EGR pipe (14, 54), and the first and second EGR coolers (21, 22) is an EGR device for an engine configured to cool the EGR gas having a temperature of 100 ° C. or higher to less than 100 ° C. in two stages,
At least the second EGR cooler (22) is located on the side of the engine (11) and extends in the vertical direction;
The EGR gas is configured to flow into the second EGR cooler (22) from its lower end or upper end and to be discharged from its upper end or lower end,
Condensed water (28) generated by the second EGR cooler (22) or the first and second EGR coolers (21, 22) on the EGR pipe (14, 54) connected to the lower end of the second EGR cooler (22) A drain mechanism (17) for storing and discharging the gas is connected at a position lower than a horizontal plane including the lower end of the second EGR cooler (22),
The drain pressure increasing valve (18) that opens and closes the EGR pipe (14, 54) and the EGR adjustment valve (16) sandwich the connection portion of the drain mechanism (17) to the EGR pipe (14, 54). Arranged,
Compressed air supply means (19) for supplying compressed air to the EGR pipe (14, 54) between the drain pressure increasing valve (18) and the EGR regulating valve (16) is connected,
The controller (26) controls the EGR regulating valve (16), the drain pressure increasing valve (18), the compressed air supply means (19), and the drain mechanism (17) according to the operating condition of the engine (11). The EGR cooler condensate water storage and discharge mechanism is configured as described above. The first EGR cooler (21) is provided on the side of the engine (11) and below the exhaust manifold (12a) of the exhaust passage (12) and extends in the vertical direction, and the second EGR cooler ( 22) is provided on the side of the engine (11), below the intake manifold (13a) of the intake passage (13) and extending vertically, and the upper end of the first EGR cooler (21) is Directly connected to the exhaust manifold (12a) or connected via a first communication pipe (14a) constituting a part of the EGR pipe (14), the upper end of the second EGR cooler (22) is connected to the intake air Connected directly to the manifold (13a) or via a second communication pipe (14b) constituting a part of the EGR pipe (14), the lower end of the first EGR cooler (21) is connected to the second EGR cooler. The lower end of (22) is connected via a third communication pipe (14c) that constitutes a part of the EGR pipe (14). Is, the drain mechanism (17) is provided at a position lower than the horizontal plane including the lower surface of the engine (11), said drainage booster valve (18) is the first 1EGR cooler (21) and the drain mechanism (17) The EGR adjustment valve (16) is provided in the third communication pipe (14c) between the connection part to the third communication pipe (14c) and the third communication pipe (14c) of the drain mechanism (17 ). The EGR cooler condensate water storage and discharge mechanism according to claim 1, which is provided in the third communication pipe (14 c) between the connection portion to the second EGR cooler (22). The first EGR cooler (21) is provided above the engine (11) and extends in the horizontal direction, and the second EGR cooler (22) is positioned on the side of the engine (11) and in the vertical direction. One end of the first EGR cooler (21) is provided through the first communication pipe (54a) constituting a part of the EGR pipe (54) to the exhaust manifold (12a) of the exhaust passage (12). An upper end of the second EGR cooler (22) is connected to the other end of the first EGR cooler (21) via a second communication pipe (54b) constituting a part of the EGR pipe (54), The lower end of the second EGR cooler (22) is connected to the intake manifold (13a) of the intake passage (13) via a third communication pipe (54c) constituting a part of the EGR pipe (54), and the drain mechanism (17) is provided at a position lower than a horizontal plane including the lower surface of the engine (11), and the drain pressure increasing valve (18) is provided in the second EG. Provided in the third communication pipe between the connecting portion of the third communicating tube cooler (22) and the drain mechanism (17) to (54c) (54c), said EGR control valve (16) is the drain The condensed water of the EGR cooler according to claim 1, provided in the third communication pipe (54c) between a connection portion of the mechanism (17) to the third communication pipe (54c) and the intake manifold (13a). Storage and discharge mechanism.   The drain mechanism (17) is connected to the third communication pipe (14c, 54c) and extends downward, and a drain tank (17b) provided in the middle of the drain pipe (17a) 4. The EGR cooler condensate water storage according to claim 2, further comprising: a drain valve (17 c) provided in the drain pipe (17 a) below the drain tank (17 b) for opening and closing the drain pipe (17 a). And discharge mechanism.

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