JP2014181629A - Exhaust gas recirculation device of engine for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device of an engine for a turbocharger-mounted vehicle capable of reducing the number of components, the weight, and the cost with a simple structure.SOLUTION: An exhaust gas introduction passage 20 having an upstream end connected to an exhaust passage 4 on an exhaust downstream side of an exhaust catalyst 16 and having a branch part 19 on a downstream end thereof, a low pressure exhaust gas recirculation passage 21 for communicating the branch part 19 with an intake passage 3 on an intake upstream side of a compressor 7 of a turbocharger 5, and a high pressure exhaust gas recirculation passage 22 for communicating the branch part 19 with the intake passage 3 on an intake downstream side of the compressor 7 are formed in an exhaust gas recirculation passage 18. A switching valve 24 with a flow rate adjusting function is arranged in the branch part 19. The switching valve 24 is switched to any of a state for communicating the exhaust gas introduction passage 20 with the low pressure exhaust gas recirculation passage 21, a state for communicating the exhaust gas introduction passage 20 with the high pressure exhaust gas recirculation passage 22, and a state for not communicating the exhaust gas introduction passage 20 with any of them.

Description

  The present invention relates to an exhaust gas recirculation device for a vehicle engine used in a vehicle, and is particularly suitable for an exhaust gas recirculation device for a vehicle engine equipped with a turbocharger.

  The exhaust gas recirculation system returns a part of the exhaust gas to the combustion chamber of the engine, thereby lowering the combustion temperature, reducing NOx and knocking, further reducing pump loss, and increasing fuel consumption in a high load range. It is to ease. In a turbocharged vehicle in which a compressor is arranged in the intake passage and a turbine is arranged in the exhaust passage, it is possible to select whether the exhaust gas recirculation destination is the intake upstream side or the intake downstream side of the compressor. As an exhaust gas recirculation device for a vehicle engine equipped with a turbocharger as described above, for example, there is one described in Patent Document 1 below. In this exhaust gas recirculation device for a vehicle engine, a low pressure exhaust gas recirculation passage that recirculates a part of the exhaust gas from the compressor of the turbocharger to the intake upstream side, and a high pressure exhaust gas recirculation passage that recirculates from the compressor to the intake downstream side. Forming. Then, an EGR valve composed of an on-off valve is arranged in each of the low pressure exhaust gas recirculation passage and the high pressure exhaust gas recirculation passage, and a part of the exhaust gas is recirculated to the low pressure exhaust gas recirculation passage side or the high pressure exhaust gas return is returned. It is controlled whether it is recirculated to the flow passage side or whether it is recirculated to the low pressure exhaust gas recirculation passage or the high pressure exhaust gas recirculation passage.

JP 2008-128043 A

  However, in the exhaust gas recirculation device for a vehicle engine described in Patent Document 1, on-off valves must be arranged in both the low-pressure exhaust gas recirculation passage and the high-pressure exhaust gas recirculation passage. The number of points is also high, which causes high costs.

  The present invention has been made paying attention to the above-mentioned problems, and by arranging a switching valve at a branch portion between the low pressure exhaust gas recirculation passage and the high pressure exhaust gas recirculation passage, the structure is simple, and the parts An object of the present invention is to provide an exhaust gas recirculation device for a vehicle engine that can reduce the number of points and weight and can reduce the cost.

  In order to solve the above problems, an embodiment of the present invention is arranged in a compressor disposed in an intake passage of an engine and an exhaust passage of the engine in an exhaust gas recirculation device for a vehicle engine that recirculates exhaust gas to the intake side. A turbocharger having a turbine; an exhaust catalyst disposed in an exhaust passage downstream of the turbine; an exhaust gas recirculation passage connecting the exhaust passage and the intake passage; and the exhaust gas recirculation passage; A recirculation upstream end is connected to an exhaust passage on the exhaust downstream side of the exhaust catalyst, and an exhaust gas introduction passage having a branch portion at the recirculation downstream end portion is formed in the exhaust gas recirculation passage. The branch portion and the compressor A low pressure exhaust gas recirculation passage communicating with the intake passage on the upstream side of the intake air, and the exhaust gas recirculation passage; A high-pressure exhaust gas recirculation passage that communicates with the intake passage downstream of the presser, and a state that is provided in the branch portion and that communicates the exhaust gas introduction passage and the low-pressure exhaust gas recirculation passage, the exhaust gas introduction passage And a switching valve for switching the exhaust gas introduction passage to either the low pressure exhaust gas recirculation passage or the high pressure exhaust gas recirculation passage. This is an exhaust gas recirculation device for a vehicle engine.

  Further, an exhaust gas flow rate adjusting valve is disposed in the exhaust gas introduction passage.

  Further, an exhaust gas flow rate adjusting function is added to the switching valve.

  An exhaust gas cooler for cooling the exhaust gas is disposed in the exhaust gas introduction passage.

  Thus, according to an embodiment of the invention, the compressor of the turbocharger is arranged in the intake passage of the engine and the turbine is arranged in the exhaust passage. An exhaust catalyst is arranged in the exhaust passage downstream of the turbine, and the exhaust passage and the intake passage are connected by an exhaust gas recirculation passage. The exhaust gas recirculation passage includes an exhaust gas introduction passage having a recirculation upstream end connected to an exhaust passage downstream of the exhaust catalyst and having a branch at the recirculation downstream end, and an intake upstream of the branch and the compressor. A low-pressure exhaust gas recirculation passage that communicates with the intake passage, and a high-pressure exhaust gas recirculation passage that communicates between the branch portion and the intake passage downstream of the compressor. The branch portion is connected to the exhaust gas introduction passage and the low pressure exhaust gas recirculation passage, the exhaust gas introduction passage is connected to the high pressure exhaust gas recirculation passage, and the exhaust gas introduction passage is connected to the low pressure exhaust gas recirculation passage. And a switching valve for switching to any state not communicating with any of the high-pressure exhaust gas recirculation passages. Therefore, the exhaust gas from which the substance to be removed by the exhaust catalyst is removed can be introduced into the exhaust gas introduction passage, and further introduced into the low pressure exhaust gas recirculation passage and the high pressure exhaust gas recirculation passage. In addition, since a common exhaust gas introduction passage can be used for the low pressure exhaust gas recirculation passage and the high pressure exhaust gas recirculation passage, the structure is simplified, the weight can be reduced, and the apparatus can be downsized. It becomes. Furthermore, since one switching valve is sufficient, the structure is simplified, the number of parts and the weight can be reduced, and the apparatus can be reduced in size and cost.

  Further, since the exhaust gas flow rate adjusting valve is disposed in the exhaust gas introduction passage, the flow rate of the exhaust gas recirculated through the low pressure exhaust gas recirculation passage or the high pressure exhaust gas recirculation passage can be adjusted.

  In addition, since the exhaust gas flow rate adjustment function is added to the switching valve, the flow rate of the exhaust gas recirculated through the low pressure exhaust gas recirculation passage or the high pressure exhaust gas recirculation passage can be adjusted, and the number of parts and weight can be adjusted. Increase can be suppressed.

  An exhaust gas cooler for cooling the exhaust gas is disposed in the exhaust gas introduction passage. Therefore, a common exhaust gas cooler can be used for the low-pressure exhaust gas recirculation passage and the high-pressure exhaust gas recirculation passage, the structure is simplified, the number of parts and weight can be reduced, and the size and cost of the apparatus are reduced. Can also be made cheaper.

1 is a schematic configuration diagram illustrating a first embodiment of an exhaust gas recirculation device for a vehicle engine according to the present invention. It is a schematic block diagram which shows 2nd Embodiment of the exhaust-gas recirculation apparatus of the engine for vehicles of this invention. It is explanatory drawing of the switching valve provided in the exhaust-gas recirculation apparatus of FIG. It is explanatory drawing of the switching valve provided in the exhaust-gas recirculation apparatus of FIG. It is explanatory drawing of the switching valve provided in the exhaust-gas recirculation apparatus of FIG.

  Next, a first embodiment of an exhaust gas recirculation device for a vehicle engine according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an exhaust gas recirculation device according to the present embodiment. The vehicle engine of this embodiment includes a turbocharger 5 that supercharges combustion air. In the present embodiment, similarly to an existing vehicle engine, an intake passage 3 for supplying air to the combustion chamber 2 of the engine 1 and an exhaust passage 4 for discharging the exhaust gas of the combustion chamber 2 are provided. An air cleaner 6 that purifies the intake air is disposed in the most upstream portion of the intake passage 3. A compressor 7 of the turbocharger 5 is disposed downstream of the air cleaner 6 to compress the intake air. An intercooler 8 for cooling the intake air is arranged on the intake air downstream side of the compressor 7. A throttle valve 9 is provided on the intake air downstream side of the intercooler 8, and an intake manifold 10 is disposed on the intake air downstream side of the throttle valve 9. Air in the intake manifold 10 is supplied to the combustion chamber 2 via the intake branch pipe 11 and the intake port 12 (therefore, the intake manifold 10, the intake branch pipe 11, and the intake port 12 are also part of the intake passage 3). ). A pre-compressor pressure sensor 31 that detects the intake pressure before being compressed by the compressor 7 is provided in the intake passage 3 between the air cleaner 6 and the compressor 7. Further, the intake manifold 10 is provided with an intake manifold pressure sensor 32 that detects the intake pressure in the intake manifold 10, that is, the intake pressure after being compressed by the compressor 7.

  On the other hand, the exhaust gas in the combustion chamber 2 is discharged from the exhaust port 13 through the exhaust manifold 14 to the exhaust passage 4 (therefore, the exhaust port 13 and the exhaust manifold 14 are also part of the exhaust passage 4). A turbine 15 of a turbocharger 5 that is driven to rotate by exhaust gas is disposed on the exhaust downstream side of the exhaust manifold 14. As is well known, since the turbine 15 is rotationally driven by exhaust gas, the intake air is compressed by the coaxial compressor 7. An exhaust catalyst (catalytic converter) 16 that removes substances to be removed from the exhaust is disposed on the exhaust downstream side of the turbine 15. A muffler 17 that mainly silences the exhaust is provided on the exhaust downstream side of the exhaust catalyst 16, and exhaust gas is discharged to the atmosphere on the exhaust downstream side of the muffler 17. A post-catalyst pressure sensor 33 that detects the exhaust pressure after passing through the exhaust catalyst 16 is provided on the exhaust downstream side of the exhaust catalyst 16.

  In the present embodiment, the exhaust gas recirculation passage 18 connects the exhaust passage 4 and the intake passage 3 on the exhaust downstream side of the exhaust catalyst 16. The exhaust gas recirculation passage 18 includes an exhaust gas introduction passage 20 having a recirculation upstream end connected to the exhaust passage 4 on the exhaust downstream side of the exhaust catalyst 16 and a branching portion 19 at the recirculation downstream end, A low pressure exhaust gas recirculation passage 21 that communicates with the intake passage 3 upstream of the compressor 7 and a high pressure exhaust gas recirculation passage 22 that connects the branch portion 19 and the intake passage 3 downstream of the compressor 7 with respect to the intake air are formed. . Of these, the exhaust gas introduction passage 20 connects the exhaust passage 4 downstream of the exhaust catalyst 16, more precisely, the exhaust passage 4 downstream of the post-catalyst pressure sensor 33 and the branch portion 19. The low-pressure exhaust gas recirculation passage 21 connects the branch portion 19 and the intake passage 3 at the position where the pre-compressor pressure sensor 31 is disposed. The high pressure exhaust gas recirculation passage 22 communicates the branch portion 19 and the intake manifold 10. The intake pressure in the intake passage 3 at the position where the pre-compressor pressure sensor 31 is disposed is relatively low, and the intake pressure in the intake manifold 10 is relatively high. An exhaust gas cooler 23 that cools the introduced exhaust gas is disposed in the exhaust gas introduction passage 20.

  In the present embodiment, a switching valve 24 is disposed at the branch portion 19 of the exhaust gas recirculation passage 18. This switching valve 24 is in a state where the exhaust gas introduction passage 20 and the low pressure exhaust gas recirculation passage 21 are in communication, in a state where the exhaust gas introduction passage 20 and the high pressure exhaust gas recirculation passage 22 are in communication, and the exhaust gas introduction passage 20 is low in pressure. This is a valve that switches to either one of the exhaust gas recirculation passage 21 and the high-pressure exhaust gas recirculation passage 22, and an electromagnetic three-way valve, a rotary valve, or the like can be applied. Therefore, the exhaust gas on the exhaust gas downstream side of the exhaust catalyst 16 is returned to the intake air upstream side of the compressor 7 through the low-pressure exhaust gas recirculation passage 21, more precisely to the intake passage 3 at the position of the pre-compressor pressure sensor 31. It is possible to switch between returning to the intake air downstream side of the compressor 7 through the high-pressure exhaust gas recirculation passage 22, more precisely, to the intake manifold 10, or not recirculating to either. In the present embodiment, the exhaust gas introduction passage 20 is provided with a flow rate adjusting valve 25 for adjusting the flow rate of the recirculated exhaust gas. Therefore, the flow rate of the exhaust gas recirculated to the intake passage 3 on the intake upstream side of the compressor 7 or the intake passage 3 on the intake downstream side of the compressor 7 can be adjusted.

  The switching control of the switching valve 24 and the flow rate adjusting control of the flow rate adjusting valve 25 are performed by a controller (control device) 34. In the controller 34, for example, the intake air pressure upstream of the compressor 7 detected by the pre-compressor pressure sensor 31, the intake air pressure downstream of the compressor 7 detected by the intake manifold pressure sensor 32, and the post-catalyst pressure sensor 33 detect The switching control of the switching valve 24 and the flow rate adjustment control of the flow rate adjustment valve 25 are performed based on the exhaust pressure on the exhaust downstream side of the exhaust catalyst 16 to be performed. According to the controller 34, the exhaust gas recirculation amount to the high-pressure exhaust gas recirculation passage 22 side increases as the load on the engine 1 increases. The lower the load on the engine 1, the closer to the low-pressure exhaust gas recirculation passage 21 side. Increase the exhaust gas recirculation amount.

  Thus, in the exhaust gas recirculation device for a vehicle engine according to this embodiment, the compressor 7 of the turbocharger 5 is disposed in the intake passage 3 of the engine 1 and the turbine 15 is disposed in the exhaust passage 4. An exhaust catalyst 16 is disposed in the exhaust passage 4 on the exhaust downstream side of the turbine 15, and the exhaust passage 4 and the intake passage 3 are connected to each other by an exhaust gas recirculation passage 18. The exhaust gas recirculation passage 18 includes an exhaust gas introduction passage 20 having a recirculation upstream end connected to the exhaust passage 4 on the exhaust downstream side of the exhaust catalyst 16 and a branching portion 19 at the recirculation downstream end, and a branching portion 19. And a low pressure exhaust gas recirculation passage 21 that connects the intake passage 3 upstream of the compressor 7 and a high pressure exhaust gas recirculation passage 22 that connects the branch portion 19 and the intake passage 3 downstream of the compressor 7. To do. The branch portion 19 is connected to the exhaust gas introduction passage 20 and the low pressure exhaust gas recirculation passage 21, the state is connected to the exhaust gas introduction passage 20 and the high pressure exhaust gas recirculation passage 22, and the exhaust gas introduction passage 20. Is provided with a switching valve 24 for switching between the low pressure exhaust gas recirculation passage 21 and the high pressure exhaust gas recirculation passage 22. Therefore, the exhaust gas from which the substance to be removed by the exhaust catalyst 16 is removed can be introduced into the exhaust gas introduction passage 20 and further introduced into the low pressure exhaust gas recirculation passage 21 and the high pressure exhaust gas recirculation passage 22. Further, since the common exhaust gas introduction passage 20 can be used for the low pressure exhaust gas recirculation passage 21 and the high pressure exhaust gas recirculation passage 22, the structure can be simplified, the weight can be reduced, and the apparatus can be reduced in size. Can be realized. Furthermore, since only one switching valve 24 is required, the structure is simplified, the number of parts and the weight can be reduced, and the apparatus can be downsized and the cost can be reduced.

  In addition, since the exhaust gas flow rate adjusting valve 25 is disposed in the exhaust gas introduction passage 20, it is possible to adjust the flow rate of the exhaust gas recirculated through the low pressure exhaust gas recirculation passage 21 or the high pressure exhaust gas recirculation passage 22.

  Further, an exhaust gas cooler 23 for cooling the exhaust gas is disposed in the exhaust gas introduction passage 20. Therefore, a common exhaust gas cooler 23 can be used for the low pressure exhaust gas recirculation passage 21 and the high pressure exhaust gas recirculation passage 22, the structure is simplified, the number of parts and the weight can be reduced, and the size of the apparatus can be reduced. And cost reduction.

  Next, a second embodiment of the exhaust gas recirculation device for a vehicle engine according to the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram of the exhaust gas recirculation device of the present embodiment. The exhaust gas recirculation device of the present embodiment is substantially the same as that shown in FIG. 1 of the first embodiment, and the same components are denoted by the same reference numerals, and detailed description thereof is omitted. In the present embodiment, the flow rate adjustment valve disposed in the exhaust gas introduction passage 20 in the first embodiment is removed, and a flow rate adjustment function is added to the switching valve 24 provided in the branch portion 19. 3 to 5 show the switching valve 24 of this embodiment to which a flow rate adjusting function is added. The switching valve 24 of the present embodiment is a rotary valve in which a rotor 27 is rotatably accommodated in, for example, a cylindrical valve body 26. The rotor 27 can control the rotation angle by, for example, an electric motor.

  The switching valve 24 with the flow rate adjusting function is in a state in which the exhaust gas introduction passage 20 and the low pressure exhaust gas recirculation passage 21 are in communication, in a state in which the exhaust gas introduction passage 20 and the high pressure exhaust gas recirculation passage 22 are in communication, and the exhaust gas. In addition to the function of switching the introduction passage 20 to a state in which neither the low-pressure exhaust gas recirculation passage 21 nor the high-pressure exhaust gas recirculation passage 22 communicates, the intake passage on the intake upstream side of the compressor 7 via the low-pressure exhaust gas recirculation passage 21 3 or a function of adjusting the flow rate of exhaust gas recirculated to the intake passage 3 on the intake downstream side of the compressor 7 via the high-pressure exhaust gas recirculation passage 22. The rotor 27 rotates with the central axis of the cylindrical valve body 26 as the rotation axis. The rotor 27 is provided with land portions 28 that are in contact with the inner peripheral surface of the circular hole of the valve body 26 symmetrically about the rotation axis, and an exhaust gas introduction passage is provided between the two land portions 28. 20 and a low-pressure exhaust gas recirculation passage 21 or a passage portion 29 for connecting the exhaust gas introduction passage 20 and the high-pressure exhaust gas recirculation passage 22 is formed.

  For example, as shown in FIG. 3, the switching valve 24 with the flow rate adjusting function is configured such that the land portion 28 is in the exhaust gas introduction passage 20 in a state where any one land portion 28 faces the exhaust gas introduction passage 20. Therefore, the exhaust gas introduction passage 20 does not communicate with either the low pressure exhaust gas recirculation passage 21 or the high pressure exhaust gas recirculation passage 22. From this state, for example, as shown in FIG. 4, when the rotor 27 is rotated in the counterclockwise direction in the figure, the land part 28 is disengaged from the opening of the exhaust gas introduction passage 20 to the left in the figure, and the right-side passage part 29 in the figure. The exhaust gas introduction passage 20 is communicated with the high pressure exhaust gas recirculation passage 22 through the. At this time, the opening area of the exhaust gas introduction passage 20 increases as the amount of rotation of the rotor 27 in the counterclockwise direction shown in the figure increases, so that the compressor is connected via the high-pressure exhaust gas recirculation passage 22 according to the increase or decrease of the opening area. 7 can be adjusted to increase or decrease the flow rate of the exhaust gas recirculated to the intake passage 3 on the intake downstream side. 3, when the rotor 27 is rotated in the clockwise direction in the figure as shown in FIG. 5, for example, the land part 28 is disengaged from the opening of the exhaust gas introduction passage 20 to the right in the figure, The exhaust gas introduction passage 20 is connected to the low pressure exhaust gas recirculation passage 21 through the passage portion 29. Also at this time, the opening area of the exhaust gas introduction passage 20 increases as the amount of rotation of the rotor 27 in the clockwise direction in the drawing increases, so that the compressor is connected via the low-pressure exhaust gas recirculation passage 21 according to the increase or decrease of the opening area. 7 can be adjusted to increase or decrease the flow rate of the exhaust gas recirculated to the intake passage 3 on the intake upstream side.

  As described above, in the exhaust gas recirculation device for a vehicle engine according to the present embodiment, in addition to the effects of the first embodiment, the switching valve 24 is provided with the exhaust gas flow rate adjusting function, so that the low pressure exhaust gas recirculation passage 21 or the high pressure exhaust gas is provided. The flow rate of the exhaust gas recirculated through the recirculation passage 22 can be adjusted, and the increase in the number of parts and weight can be suppressed.

1 is an engine 2 is a combustion chamber 3 is an intake passage 4 is an exhaust passage 5 is a turbocharger 6 is an air cleaner 7 is a compressor 8 is an intercooler 9 is a throttle valve 10 is an intake manifold 11 is an intake branch pipe 12 is an intake port 13 is an exhaust port 14 is an exhaust manifold 15 is a turbine 16 is an exhaust catalyst 17 is a muffler 18 is an exhaust gas recirculation passage 19 is a branching portion 20 is an exhaust gas introduction passage 21 is a low pressure exhaust gas recirculation passage 22 is a high pressure exhaust gas recirculation passage 23 is an exhaust gas cooler 24 The switching valve 25 is a flow rate adjusting valve 26 is a valve body 27 is a rotor 28 is a land portion 29 is a passage portion 31 is a pre-compressor pressure sensor 32 is an intake manifold pressure sensor 33 is a post-catalyst pressure sensor 34 is a controller (control device)

Claims (4)

In an exhaust gas recirculation device for a vehicle engine that recirculates exhaust gas to the intake side,
A turbocharger having a compressor disposed in an intake passage of an engine and a turbine disposed in an exhaust passage of the engine;
An exhaust catalyst disposed in an exhaust passage downstream of the turbine,
An exhaust gas recirculation passage connecting the exhaust passage and the intake passage;
An exhaust gas introduction passage formed in the exhaust gas recirculation passage, having a recirculation upstream end connected to an exhaust passage downstream of the exhaust catalyst and having a branch at the recirculation downstream end;
A low-pressure exhaust gas recirculation passage formed in the exhaust gas recirculation passage and connecting the branch portion and the intake passage upstream of the compressor;
A high-pressure exhaust gas recirculation passage formed in the exhaust gas recirculation passage and connecting the branch portion and the intake passage on the intake downstream side of the compressor;
A state in which the exhaust gas introduction passage communicates with the low pressure exhaust gas recirculation passage; a state in which the exhaust gas introduction passage communicates with the high pressure exhaust gas recirculation passage; and the exhaust gas introduction passage, An exhaust gas recirculation device for a vehicle engine, comprising: a switching valve that switches to either one of the low pressure exhaust gas recirculation passage and the high pressure exhaust gas recirculation passage.   2. The exhaust gas recirculation device for a vehicle engine according to claim 1, wherein an exhaust gas flow rate adjusting valve is disposed in the exhaust gas introduction passage.   2. The exhaust gas recirculation device for a vehicle engine according to claim 1, wherein an exhaust gas flow rate adjusting function is added to the switching valve.   The exhaust gas recirculation device for a vehicle engine according to any one of claims 1 to 3, wherein an exhaust gas cooler for cooling the exhaust gas is disposed in the exhaust gas introduction passage.

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