JP5589953B2 - EGR device - Google Patents

Description

  The present invention relates to a technical field of an EGR (Exhaust Gas Recirculation) device for a supercharged engine mounted on a vehicle.

  As this type of device, for example, an EGR device for an engine with a supercharger, which is coaxially driven by a turbine driven by exhaust gas through an EGR exhaust passage branched from the exhaust passage into an EGR passage and the turbine There has been proposed an EGR device that includes a compressor, and is provided with an EGR supercharger that pressurizes the EGR gas in the EGR passage by the compressor and feeds the gas through the EGR valve to the supply passage. In particular, it is described that the EGR valve is released only when the EGR gas pressure is larger than the supply pressure detection value (that is, only when the supply air in the supply pipe does not flow into the EGR pipe side) (patent) Reference 1).

  Alternatively, for example, in an engine EGR device with a supercharger, when the load of the engine is lower than a predetermined load, the supply air disposed in the intake passage from the downstream of the particulate filter disposed in the exhaust passage An EGR device has been proposed that recirculates exhaust to the downstream of the cooler and recirculates exhaust from the downstream of the particulate filter to the upstream of the charge air cooler when the engine load is higher than the specified load (Patent Document 2). reference).

  Alternatively, for example, an EGR device for an engine with a supercharger, in which an EGR cooler that exchanges heat between EGR gas and cooling water of an engine cooling system is disposed in the EGR passage. An EGR device that promotes warm-up of the engine during cold operation has been proposed (see Patent Document 3).

JP 2004-100508 A JP 2006-022770 A JP 2011-017315 A

  However, according to the background art described above, there is a technical problem that the temperature adjustment of the gas passing through the EGR passage may not be sufficient.

  This invention is made | formed in view of the said problem, for example, and makes it a subject to propose the EGR apparatus which can perform suitably the temperature adjustment of the gas which passes an EGR channel | path.

In order to solve the above problems, an EGR device of the present invention includes (i) a turbocharger that is mounted on a vehicle, (ii) includes a compressor disposed in an intake passage and a turbine disposed in an exhaust passage, and (iii) And an intercooler that cools the gas flowing in the intake passage, and is disposed on the downstream side of the compressor in the intake passage, and is mounted on an upstream side of the turbine in the exhaust passage, and in the intake passage A first flow path communicating with the downstream side of the intercooler; a second flow path communicating with the upstream side of the turbine in the exhaust passage; and the downstream side of the compressor and the upstream side of the intercooler in the intake passage. When the first flow path and the second flow path includes a switching means for switching to one another, wherein the switching means, the acceleration needed for the vehicle And when the pressure associated with the intake passage is greater than the pressure associated with the exhaust passage, the gas flowing through the intake passage is supplied to the exhaust passage without passing through the intercooler. Switch to the second flow path.

  According to the EGR device of the present invention, the engine on which the EGR device is mounted is mounted on a vehicle such as an automobile. The engine includes a compressor disposed in an intake passage and a turbocharger disposed in an exhaust passage, and a gas (for example, a gas flowing through the intake passage) disposed downstream of the compressor of the supercharger in the intake passage. And an intercooler for cooling the intake air and the like.

  The EGR device includes a first flow path that communicates an upstream side of a turbine of a supercharger in an exhaust passage and a downstream side of an intercooler in an intake passage, an upstream side of the turbine of the supercharger in an exhaust passage, and an intake passage A second flow path communicating with the downstream side of the compressor of the supercharger and the upstream side of the intercooler, and switching means for switching the first flow path and the second flow path to each other. Note that the flow direction of the gas in each of the first flow path and the second flow path is not limited to the direction from the exhaust passage to the intake passage, and may be the direction from the intake passage to the exhaust passage.

In the EGR device configured as described above, for example, the first
If the flow path and the second flow path are switched to each other, the temperature of the exhaust gas recirculated from the exhaust passage to the intake passage can be appropriately adjusted via the first flow path or the second flow path. Particularly in the present invention, the switching means switches to the second flow path when there is an acceleration request for the vehicle and the pressure related to the intake passage is larger than the pressure related to the exhaust passage. Here, “switching to the second flow path” is not limited to switching from the first flow path to the second flow path when the gas flows through the first flow path, and (i) the gas is the second flow path. Maintain the state when flowing through the flow path, and (ii) when no gas flows through either the first flow path or the second flow path, the gas flows through the second flow path. Including.

  Specifically, for example, when the engine is operating at a relatively light load, if the switching means is switched to the first flow path so as to recirculate the exhaust gas to the downstream side of the intercooler in the intake passage, the comparison is made. Since the exhaust gas having a high temperature is supplied into the engine, for example, misfire of the engine can be suppressed. On the other hand, when the engine is operating at a relatively high load, if the switching means is switched to the second flow path so as to recirculate the exhaust gas to the upstream side of the intercooler in the intake passage, it is cooled by the intercooler. Since the exhaust gas is supplied into the engine, for example, the occurrence of knocking can be suppressed.

  Further, when the pressure related to the intake passage (ie, the intake pressure) is higher than the pressure related to the exhaust passage (ie, the back pressure), from the upstream side of the intercooler in the intake passage to the upstream side of the turbine in the exhaust passage. If the switching means switches to the second flow path so as to supply intake air, relatively high-temperature intake air that is not cooled by the intercooler can be supplied to the turbine of the supercharger. The rotational speed can be increased.

  As a result, according to the EGR device of the present invention, the temperature of the gas passing through the EGR passage can be adjusted suitably.

  The effect | action and other gain of this invention are clarified from the form for implementing demonstrated below.

It is a schematic block diagram which shows the principal part of the vehicle by which the EGR apparatus which concerns on embodiment of this invention is mounted. It is a flowchart which shows the control processing of the EGR cooler and EGR valve which concern on embodiment of this invention.

  An embodiment according to an EGR device of the present invention will be described with reference to the drawings.

  First, a vehicle according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram illustrating a main part of a vehicle on which the EGR device according to the present embodiment is mounted. In addition, the solid line arrow in FIG. 1 represents the flow of gas, and the dotted line represents the flow path of the cooling medium (for example, cooling water).

  In FIG. 1, a vehicle 1 includes an engine 11, an intake passage (intake manifold: intake manifold) 12 connected to the engine 11, an exhaust passage 13 connected to the engine 11, and a compressor disposed in the intake passage 12. 14c and the supercharger 14 which has the turbine 14t arrange | positioned at the exhaust passage 13, the intake manifold intercooler 15 arrange | positioned at the intake passage 12, the EGR apparatus 16, the intercooler 17, and ECU (Electronic Control Unit: Electronic control) Unit) 20.

  The EGR device 16 includes EGR passages 161, 162, and 163, an EGR valve 164, an EGR cooler 165, and a flow path switching valve 166.

  Here, the EGR passage 161 is a passage connecting the upstream side of the turbine 14 t of the supercharger 14 in the exhaust passage 13 and the flow path switching valve 166. The EGR passage 162 is a passage connecting the downstream side of the intake manifold intercooler 15 in the intake passage 12 and the flow path switching valve 166. The EGR passage 163 is a passage connecting the flow path switching valve 166 to the downstream side of the compressor 14 c of the supercharger 14 and the upstream side of the intake manifold intercooler 15 in the intake passage 12.

  The EGR passages 161 and 162 constitute an example of the “first flow path” according to the present invention, and the EGR passages 161 and 163 constitute an example of the “second flow path” according to the present invention. Yes.

  In the EGR cooler 165, the cooling medium passage 31 through which the cooling medium that exchanges heat with the engine 11 flows, and the cooling medium through which the cooling medium that exchanges heat with the outside air in each of the intake manifold intercooler 15 and the intercooler 17 flows. The medium flow path 33 is connected. Here, since the temperature of the cooling medium flowing in the cooling medium passage 31 is higher than the temperature of the cooling medium flowing in the cooling medium passage 33, the cooling medium flowing in the cooling medium passage 31 is referred to as “high temperature cooling medium” for convenience of explanation. The cooling medium flowing in the cooling medium passage 33 is appropriately referred to as “low temperature cooling medium”.

  As shown in FIG. 1, a coolant passage 32 that bypasses the EGR cooler 165 also exists in the coolant passage through which the high-temperature coolant flows. The cooling medium passage 31 and the cooling medium passage 32 are switched to each other when the valves v2 and v3 are controlled by the ECU 20. Further, a cooling medium passage 34 that bypasses the EGR cooler 165 also exists in the cooling medium passage through which the low-temperature cooling medium flows. The cooling medium passage 33 and the cooling medium passage 34 are switched to each other when the valve v <b> 1 is controlled by the ECU 20.

  Next, control processing of the EGR cooler 165 and the EGR valve 164 executed by the ECU 20 in the vehicle 1 configured as described above will be described with reference to the flowchart of FIG.

  In FIG. 2, the ECU 20 first determines whether or not the engine 11 is warming up (step S101). Whether or not the engine 11 is warming up may be determined, for example, by detecting the temperature of the engine 11 or the like. In any case, since various known modes can be applied to the method for determining whether or not the engine 11 is warming up, it is omitted here.

  When it is determined that the engine 11 is warming up (step S101: Yes), the ECU 20 causes a part of the exhaust gas to be downstream of the intake manifold 12 in the intake passage 12 via the EGR passages 161 and 162. The EGR valve 164 and the flow path switching valve 166 are controlled so as to be recirculated. The ECU 20 further controls the valves v1, v2, and v3 so that only the high-temperature cooling medium is supplied to the EGR cooler 165 (step S102).

  Then, atomization of the fuel supplied to the engine 11 is promoted due to the recirculation of the relatively high temperature exhaust gas to the engine 11. Furthermore, the temperature of the engine 11 rises due to heat exchange between the high-temperature cooling medium warmed in the EGR cooler 165 and the engine 11 (when the engine 11 is warmed up, the temperature of the high-temperature cooling medium warmed in the EGR cooler 165 is Is higher than the temperature of the engine 11). As a result, warming up of the engine 11 is promoted.

  If it is determined in step S101 that the engine 11 is not warming up (step S101: No), the ECU 20 determines whether the load state of the engine 11 is a light load state (step S103). ). Specifically, for example, the ECU 20 detects an actual load of the engine 11 and compares the detected load with a predetermined threshold value to determine whether or not the load state of the engine 11 is a light load state. . The predetermined threshold may be set appropriately for each specification of the engine 11.

  When it is determined that the load state of the engine 11 is a light load state (step S103: Yes), the ECU 20 causes a part of the exhaust gas to flow into the intake manifold 12 in the intake passage 12 via the EGR passages 161 and 162. The EGR valve 164 and the flow path switching valve 166 are respectively controlled so as to be returned to the downstream side. The ECU 20 further controls the valves v1, v2, and v3 so that only the high-temperature cooling medium is supplied to the EGR cooler 165 (step S104).

  Then, atomization of the fuel supplied to the engine 11 is promoted due to the recirculation of the relatively high temperature exhaust gas to the engine 11. Furthermore, since the exhaust gas to be recirculated is cooled in the EGR cooler 165, the volume of the exhaust gas to be recirculated is reduced, and the controllability of EGR can be improved. As a result, misfire of the engine 11 due to the exhaust gas being recirculated can be prevented.

  When it is determined in the process of step S103 that the load state of the engine 11 is not a light load state (step S103: No), the ECU 20 determines whether or not the load state of the engine 11 is a medium to high load state ( Step S105). Specifically, for example, the ECU 20 detects an actual load of the engine 11 and compares the detected load with a predetermined threshold value to determine whether or not the load state of the engine 11 is a medium / high load state. . The predetermined threshold may be set appropriately for each specification of the engine 11.

  When it is determined that the load state of the engine 11 is a medium / high load state (step S105: Yes), the ECU 20 causes the turbocharger 14 in the intake passage 12 to partially convert the exhaust gas via the EGR passages 161 and 163. The EGR valve 164 and the flow path switching valve 166 are respectively controlled so as to return to the downstream side of the compressor 14 c and the upstream side of the intake manifold intercooler 15. The ECU 20 further controls the valves v1, v2, and v3 so that the high-temperature cooling medium and the low-temperature cooling medium are supplied to the EGR cooler 165 (step S106).

  As a result, the exhaust gas to be recirculated is cooled in both the EGR cooler 165 and the intake manifold intercooler 15, so that the occurrence of knocking can be effectively suppressed. In addition, since the capacity of the EGR cooler 165 can be reduced by using the intake manifold intercooler 15, it is very advantageous in practice.

  When it is determined in the process of step S105 that the load state of the engine 11 is not the middle / high load state (step S105: No), the EGR 20 causes a part of the intake air to pass through the EGR passages 163 and 161 in the exhaust passage 13. The EGR valve 164 and the flow path switching valve 166 are controlled so as to be supplied to the upstream side of the turbine 14 t of the supercharger 14. The ECU 20 further controls the valve v1 so that a part of the intake air is not cooled in the EGR cooler 165 (that is, the high temperature cooling medium flows through the cooling medium passage 32 and the low temperature cooling medium flows through the cooling medium passage 34). , V2 and v3 are respectively controlled (step S107).

  In this case, typically, when the vehicle 1 is accelerating and the intake pressure is higher than the back pressure, intake air flows into the exhaust passage 13 via the EGR passages 163 and 161. At this time, since the intake air is not cooled by the EGR cooler 165, relatively high temperature intake air flows into the turbine 14 t of the supercharger 14 disposed in the exhaust passage 13. As a result, when the rotational speed of the turbine 14t is increased using the blow-by, the temperature drop of the intake air blown through is suppressed, and thus the decrease in the rotational speed of the turbine 14t can be suppressed.

  Note that the “in-manifold intercooler 15” and the “flow path switching valve 166” according to the present embodiment are examples of the “intercooler” and the “switching unit” according to the present invention, respectively.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and an EGR device with such a change is also applicable. Moreover, it is included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 11 ... Engine, 12 ... Intake passage, 13 ... Exhaust passage, 14 ... Supercharger, 15 ... In manifold intercooler, 16 ... EGR device, 17 ... Intercooler, 20 ... EUC, 161, 162, 163 ... EGR passage, 164 ... EGR valve, 165 ... EGR cooler, 166 ... flow path switching valve

Claims (1)

(I) mounted on a vehicle, (ii) a turbocharger having a compressor disposed in an intake passage and a turbine disposed in an exhaust passage, and (iii) disposed downstream of the compressor in the intake passage, And an intercooler that cools the gas flowing through the intake passage,
A first flow path communicating the upstream side of the turbine in the exhaust passage and the downstream side of the intercooler in the intake passage;
A second flow path communicating with the upstream side of the turbine in the exhaust passage and the downstream side of the compressor and the upstream side of the intercooler in the intake passage;
Switching means for switching the first flow path and the second flow path to each other;
Equipped with a,
The switching means has an acceleration request for the vehicle, and when the pressure related to the intake passage is larger than the pressure related to the exhaust passage, the gas flowing through the intake passage does not pass through the intercooler. Switch to the second flow path so as to be supplied to the exhaust passage
An EGR device characterized by that.

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