JP2019167912A - Exhaust recirculation device - Google Patents

Abstract

To easily discharge condensate water occurring from EGR gas.SOLUTION: An exhaust recirculation device comprises: an EGR passage 26 of which one end communicates with an exhaust passage and the other end side is branched into a first passage 30 and a second passage 31; a throttle part 30a provided in the first passage 30 and having a passage cross-sectional area made narrower toward the other end side; and a valve (branch valve 29) provided in the EGR passage 26, and configured to adjust the opening degree of one or both of the first passage 30 and the second passage 31. Since condensate water is refined and easily vaporized by the throttle part 30a, the situation in which each part is deteriorated due to accumulation of the condensate water is suppressed, and the condensate water is easily discharged out of the vehicle together with exhaust gas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an exhaust gas recirculation device.

  Conventionally, vehicles equipped with an exhaust gas recirculation device have been widely used. For example, as described in Patent Document 1, in an exhaust gas recirculation device, an EGR cooler is provided in an EGR passage through which EGR gas recirculates to an intake passage. When the EGR gas is cooled by the EGR cooler, moisture in the EGR gas may be condensed and condensed water may be generated.

JP 2007-023911 A

  The condensed water is acidic and can be a cause of deterioration of each part that comes into contact. For this reason, it is desirable that the condensed water is appropriately discharged without stagnation.

  Accordingly, an object of the present invention is to provide an exhaust gas recirculation device that can easily discharge condensed water generated from EGR gas.

  In order to solve the above-mentioned problems, an exhaust gas recirculation apparatus according to the present invention is provided in an EGR passage having one end communicating with an exhaust passage and the other end branching into a first passage and a second passage, and the other end. A throttle portion whose passage cross-sectional area is narrowed toward the side, and a valve that is provided in the EGR passage and adjusts the opening degree of one or both of the first passage and the second passage.

  When the engine coolant temperature or the intake air temperature is less than the threshold value, a valve control unit may be provided that controls the valve so that the opening degree of the first passage is larger than when the engine coolant temperature or the intake temperature is equal to or higher than the threshold value.

  Of the first passage, the end on the intake passage side may extend in the direction of intake air flow in the intake passage.

  The first passage may be arranged at a position lower than the second passage.

  According to the present invention, the condensed water generated from the EGR gas can be easily discharged.

It is the schematic of the engine provided with the exhaust gas recirculation apparatus. It is explanatory drawing for demonstrating an EGR channel | path. It is explanatory drawing for demonstrating a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a schematic view of an engine 1 provided with an exhaust gas recirculation device 100. First, the schematic configuration of the engine 1 will be described, and then the configuration of the exhaust gas recirculation device 100 will be described. As shown in FIG. 1, the engine 1 is, for example, a horizontally opposed four-cylinder engine. In the engine 1, two cylinder blocks 3 are arranged with the crankshaft 2 interposed therebetween. Cylinder bores 3a formed on the cylinder blocks 3 face each other. Here, a horizontally opposed four-cylinder engine is illustrated, but the type of the engine 1 on which the exhaust gas recirculation device 100 is mounted is not limited.

  A crankcase 4 is integrally formed with the cylinder block 3. A cylinder head 5 is fixed on the side of the cylinder block 3 opposite to the crankcase 4. The crankshaft 2 is rotatably supported in the crank chamber 6. The crank chamber 6 is formed by the crankcase 4.

  A piston 8 is connected to the crankshaft 2 via a connecting rod 7. The piston 8 is slidably accommodated in the cylinder bore 3a. The combustion chamber 9 is a space surrounded by the cylinder bore 3 a, the cylinder head 5, and the crown surface of the piston 8.

  An intake port 10 and an exhaust port 11 are formed in the cylinder head 5 so as to communicate with the combustion chamber 9. The tip of the intake valve 12 is located between the intake port 10 and the combustion chamber 9. The tip of the exhaust valve 13 is located between the exhaust port 11 and the combustion chamber 9.

  A space surrounded by the cylinder head 5 and the head cover 14 is a cam chamber. An intake valve cam 15 and an exhaust valve cam 16 are provided in the cam chamber. The intake valve cam 15 contacts the other end of the intake valve 12. As the intake valve cam 15 rotates, the intake valve 12 moves in the axial direction. As a result, the intake valve 12 opens and closes between the intake port 10 and the combustion chamber 9. The exhaust valve cam 16 contacts the other end of the exhaust valve 13. As the exhaust valve 13 rotates, the exhaust valve 13 moves in the axial direction. Thereby, the exhaust valve 13 opens and closes between the exhaust port 11 and the combustion chamber 9.

  An intake manifold 17 is provided on the upstream side of the intake port 10. The intake manifold 17 communicates with the intake port 10. The intake manifold 17 constitutes a part of an intake passage 18 through which intake air flows. An exhaust manifold 19 is provided on the downstream side of the exhaust port 11. The exhaust manifold 19 communicates with the exhaust port 11. The exhaust manifold 19 constitutes a part of an exhaust passage 20 through which exhaust gas flows.

  The intake manifold 17 has a collecting portion 21 and an intake pipe portion 22. The collecting portion 21 communicates with an intake upstream portion 18 a upstream of the collecting portion 21 in the intake passage 18. The collecting portion 21 is a tank into which intake air flows from the intake upstream portion 18a. The intake pipe portion 22 branches from the collecting portion 21 and the downstream end is connected to the intake port 10. In the intake passage 18, an air cleaner 23 and a throttle valve 24 are provided in this order from the upstream side in the intake upstream portion 18 a. The air cleaner 23 removes foreign matters such as dust and dust contained in the intake air. The opening degree of the throttle valve 24 is adjusted by an actuator (not shown). The flow rate of the intake air supplied to the intake manifold 17 is variable by the throttle valve 24.

  The intake air whose flow rate is adjusted by the throttle valve 24 flows into the collecting portion 21 of the intake manifold 17. The intake air flowing into the collecting portion 21 is distributed to the intake pipe portion 22 and is guided to the combustion chamber 9 through the intake port 10. An air-fuel mixture of fuel injected from an injector (not shown) and intake air is ignited by an ignition plug (not shown) provided in the cylinder head 5.

  Due to the combustion of the air-fuel mixture, the piston 8 reciprocates within the cylinder bore 3a. The power of reciprocating motion of the piston 8 is converted to power of rotational motion of the crankshaft 2 through the connecting rod 7. The exhaust gas is guided from the combustion chamber 9 to the exhaust passage 20 through the exhaust port 11 and the exhaust manifold 19. The exhaust gas is purified by the catalyst 25 provided in the exhaust passage 20 and then discharged outside the vehicle.

(Exhaust gas recirculation device 100)
The exhaust gas recirculation device 100 is a device for performing exhaust gas recirculation, and includes an intake passage 18 (intake manifold 17), an exhaust passage 20, and an EGR passage 26. The EGR passage 26 communicates the exhaust passage 20 and the collecting portion 21 of the intake manifold 17. One end of the EGR passage 26 communicates with the exhaust passage 20. The EGR passage 26 recirculates a part of the exhaust gas flowing through the exhaust passage 20 to the intake passage 18. Here, the exhaust gas recirculated to the intake passage 18 via the EGR passage 26 is referred to as EGR gas.

  An EGR cooler 27 is provided in the EGR passage 26. The EGR gas is cooled by the EGR cooler 27 and then returned to the collecting portion 21. The EGR valve 28 is provided in the EGR passage 26. The EGR valve 28 adjusts the passage width of the EGR passage 26. The flow rate of EGR gas flowing through the EGR passage 26 is controlled by the EGR valve 28.

  The EGR gas recirculated to the collecting portion 21 is supplied to the combustion chamber 9 through the intake pipe portion 22 and the intake port 10 together with the intake air flowing into the collecting portion 21 from the intake upstream portion 18a. By supplying EGR gas to the combustion chamber 9, the oxygen concentration in the combustion chamber 9 is reduced. As a result, the combustion temperature of the fuel is lowered, and the generation of NOx (nitrogen oxide) and the like is suppressed.

  By the way, when the EGR gas is cooled by the EGR cooler 27, the moisture in the EGR gas may be condensed and condensed water may be generated. This condensed water is acidic and can be a cause of deterioration of each part in contact.

  FIG. 2 is an explanatory diagram for explaining the EGR passage 26. As shown in FIG. 2, the EGR passage 26 is provided with a branch valve 29 (valve). The branch valve 29 is constituted by a three-way valve, for example. The branch valve 29 is provided downstream of the EGR valve 28 in the EGR passage 26 (see FIG. 1).

  The EGR passage 26 branches into a first passage 30 and a second passage 31 at a branch valve 29. Here, the upstream portion of the EGR passage 26 from the branch valve 29 is referred to as a pre-branch passage 32. That is, the EGR passage 26 includes the pre-branch passage 32, the first passage 30, and the second passage 31. The downstream ends of the first passage 30 and the second passage 31 (the other end of the EGR passage 26) communicate with the collecting portion 21 (see FIG. 1). The first passage 30 is disposed at a position where the height in the vertical direction is lower than that of the second passage 31. The second passage 31 is designed to have a passage sectional area through which the required maximum amount of EGR gas can flow.

  The first passage 30 is provided with a throttle portion 30a. In the throttle portion 30a, the passage cross-sectional area narrows toward the other end side (the gathering portion 21 side) of the EGR passage 26. Here, the throttle portion 30a is formed by projecting the flow path wall of the first passage 30 inward. However, the throttle portion 30a may be formed, for example, by squeezing a pipe constituting the first passage 30 inward.

  The downstream end of the pre-branch passage 32 is connected to the inlet 29 a of the branch valve 29. The upstream end of the first passage 30 is connected to the first outlet 29 b of the branch valve 29. The upstream end of the second passage 31 is connected to the second outlet 29 c of the branch valve 29.

  The EGR gas flows from the pre-branch passage 32 into the branch valve 29 through the inflow port 29a. The inflow EGR gas flows out to the first passage 30 through the first outlet 29b or out to the second passage 31 through the second outlet 29c.

  The coolant temperature sensor S1 detects the coolant temperature of the engine 1 and outputs a signal indicating the coolant temperature to the valve control unit 110. The intake air temperature sensor S2 detects the intake air temperature and outputs a signal indicating the intake air temperature to the valve control unit 110.

  The valve control unit 110 is configured by an ECU (Engine Control Unit), for example. The valve control unit 110 controls the branch valve 29 according to output signals from the cooling water temperature sensor S1 and the intake air temperature sensor S2.

  Specifically, in the branch valve 29, the opening degree of the first outlet 29b and the opening degree of the second outlet 29c are variable. That is, the branch valve 29 adjusts the opening degree of the first passage 30 and the second passage 31. The valve control part 110 controls the opening degree of the 1st outflow port 29b and the opening degree of the 2nd outflow port 29c with an actuator not shown.

  As described above, when the EGR gas is cooled by the EGR cooler 27, condensed water may be generated. Therefore, when the coolant temperature or the intake air temperature of the engine 1 is less than the threshold value, the valve control unit 110, for example, fully opens the opening of the first passage 30 and fully closes the opening of the second passage 31.

  The condensed water flowing into the first passage 30 passes through the throttle portion 30a. Condensed water is refined (atomized) by the change in flow velocity when passing through the throttle portion 30a, and is efficiently supplied to the combustion chamber 9 together with the intake air. Thereby, it can suppress that condensed water retains in the EGR channel | path 26 and the intake passage 18, and those deterioration are suppressed.

  When the cooling water temperature or the intake air temperature of the engine 1 is equal to or higher than the threshold value, condensed water is hardly generated in the EGR passage 26. For example, when the coolant temperature or the intake air temperature of the engine 1 is equal to or higher than the threshold, the valve control unit 110 fully closes the opening of the first passage 30 and fully opens the opening of the second passage 31. The EGR gas flows from the second passage 31 to the collecting portion 21 without passing through the throttle portion 30 a of the first passage 30. Therefore, pressure loss due to the throttle portion 30a is avoided.

  Further, when the required amount of EGR gas cannot be provided by the first passage 30 alone, the second passage 31 is also used. The valve control unit 110 opens both the first passage 30 (first outlet 29b) and the second passage 31 (second outlet 29c). For example, the valve control unit 110 fully opens the first passage 30 side, and adjusts the opening degree on the second passage 31 side so as to pass through the second passage 31 by a flow rate that is insufficient in the first passage 30. Thus, an amount of EGR gas in a possible range passes through the throttle portion 30a, and at least a part of the condensed water is refined.

  FIG. 3 is an explanatory diagram for explaining a modification. As shown in FIG. 3, in the modified example, the narrow portion 230 b having the narrowest passage cross-sectional area of the narrowed portion 230 a of the first passage 230 extends in the flow path direction. The narrow portion 230b is provided with a partition member 230c (indicated by cross-hatching in FIG. 3) that partitions the flow path in the width direction.

  The partition member 230c has, for example, a mesh structure. Each flow path partitioned by the partition member 230c communicates from the upstream end to the downstream end of the narrow portion 230b. The condensed water is further refined by the partition member 230c.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the embodiment and the modification described above, the case where the branch valve 29 is provided has been described. However, the branch valve 29 is not an essential component. If both the first passage 30 and the second passage 31 are provided, at least a part of the EGR gas flows into the first passage 30 and the effect of miniaturizing the condensed water is expected.

  In the embodiment and the modification described above, the case where the branch valve 29 adjusts the opening degrees of both the first passages 30 and 230 and the second passage 31 has been described. However, the branch valve 29 may adjust only the opening degree of one of the first passages 30 and 230 or the second passage 31. Even in this case, the flow rate of both the first passages 30 and 230 and the second passage 31 can be controlled by the branch valve 29 as compared with the case where the branch valve 29 is not provided.

  In the embodiment and the modification described above, the case where the branch valve 29 is provided separately from the EGR valve 28 has been described. However, the branch valve 29 may function as the EGR valve 28. In other words, the EGR valve 28 may function as the branch valve 29. In this case, for example, the branch valve 29 can independently control the opening degree of the first passages 30, 230 and the second passage 31, or can adjust the opening degree on the pre-branch passage 32 side (inlet 29 a). If it is.

  In the embodiment and the modification described above, the opening degree of the first passages 30 and 230 is larger when the valve control unit 110 is less than the threshold when the engine coolant temperature or the intake air temperature is less than the threshold. The case where the branch valve 29 is controlled has been described. However, the valve control unit 110 may control the branch valve 29 with other logic.

  In the embodiment and the modification described above, the case where the first passages 30 and 230 are arranged at a position lower than the second passage 31 has been described. In this case, the condensed water generated on the pre-branch passage 32 side tends to flow downward into the first passages 30 and 230 due to gravity. That is, it becomes easy to miniaturize by the aperture parts 30a and 230a. However, the first passages 30 and 230 may be disposed at the same height as the second passage 31 or higher than the second passage 31.

  The present invention can be used for an exhaust gas recirculation device.

1 Engine 18 Intake passage 20 Exhaust passage 26 EGR passage 29 Branch valve (valve)
30, 230 First passage 30a, 230a Restriction portion 31 Second passage 100 Exhaust gas recirculation device 110 Valve control portion

Claims (4)

An EGR passage having one end communicating with the exhaust passage and the other end branching into a first passage and a second passage;
A throttle portion provided in the first passage and having a passage cross-sectional area narrowing toward the other end side;
A valve provided in the EGR passage for adjusting the opening degree of one or both of the first passage and the second passage;
An exhaust gas recirculation device.   2. The exhaust according to claim 1, further comprising: a valve control unit that controls the valve so that an opening degree of the first passage is larger when an engine coolant temperature or an intake air temperature is lower than a threshold value than when the engine coolant temperature or intake air temperature is higher than the threshold value. Reflux apparatus.   3. The exhaust gas recirculation apparatus according to claim 1, wherein an end of the first passage on an intake passage side extends in a flow direction of intake air in the intake passage.   The exhaust gas recirculation apparatus according to any one of claims 1 to 3, wherein the first passage is disposed at a position lower than the second passage.

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