JP2017008855A - Engine system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the production of condensed water by an EGR gas in a downstream-side EGR passage rather than an EGR valve in addition to an intake passage at a cold time.SOLUTION: An engine system comprises: a high-temperature air passage 63 which introduces high-temperature air heated in an exhaust passage 5 into an intake passage 4; a flow passage switching valve 64 which is switched for making the high-temperature air from the high-temperature air passage 63 and a low-temperature air from an intake inlet 4a selectively flow to the intake passage 4; an EGR passage 52 which makes a part of exhaust emission flow to the intake passage 4 as an EGR gas, and makes it flow back to an engine 1; an EGR valve 53 which adjusts a flow rate of the EGR gas; a shunt passage 71 which shunts a part of the high-temperature air introduced into the intake passage 4 from the high-temperature air passage 63 to the downstream-side EGR passage 52 rather than the EGR valve 53; an opening/closing valve 72 which is opened and closed for adjusting the flow rate of the high-temperature air of the shunt passage 71; and an electronic control device (ECU) 50 which controls the flow rate switching valve 64, the EGR valve 53 and the opening/closing valve 72.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine system configured to recirculate a part of exhaust discharged from an engine as exhaust gas recirculation gas to an engine through an intake passage and to introduce air heated by heating means into the intake passage.

  Conventionally, as this type of technology, for example, a control device described in Patent Document 1 below is known. This apparatus includes an EGR passage that recirculates a part of exhaust discharged from an engine as an exhaust gas recirculation gas (EGR gas) to the engine through an intake passage, and heated air that introduces air heated by heating means into the intake passage. A passage and a switching valve for switching between communication and blocking of the heated air passage with respect to the intake passage. The switching valve is controlled so that the heated air passage communicates with the intake passage when the outside air introduced into the intake passage is cold when the temperature is lower than a predetermined temperature. Thus, heated air is introduced into the intake passage when it is cold to warm the intake air, and the generation of condensed water due to the introduction of EGR gas in the intake passage is suppressed.

JP 2010-184660 A

  However, in the control device described in Patent Document 1, although the intake passage is warmed up by introducing the heated air into the intake passage when it is cold, the heated air does not flow through the EGR passage. It was difficult to do. That is, even if the intake passage is warmed up, the warm-up of the EGR passage is delayed, and the low temperature state of the inner wall may be prolonged. For this reason, when EGR gas flows through the low-temperature EGR passage, condensed water may be generated in the EGR passage, and the condensed water may be taken into the engine.

  The present invention has been made in view of the above circumstances, and an object thereof is to suppress the generation of condensed water by the exhaust gas recirculation gas in the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve in addition to the intake air passage when cold. It is to provide an engine system that enables the above.

  In order to achieve the above object, an invention according to claim 1 includes an intake passage for introducing intake air into an engine, the intake passage including an intake inlet, and introducing outside air as low-temperature air from the intake inlet; An intake air amount adjustment valve for adjusting the intake air amount in the intake passage, an exhaust passage for extracting exhaust from the engine, and an intake passage for introducing high temperature air heated by the heating means into the intake passage. The high-temperature air passage is connected to the intake passage and the high-temperature air passage, and a flow path is provided to selectively flow the high-temperature air from the high-temperature air passage and the low-temperature air from the intake inlet to the downstream side of the intake passage. A flow path switching valve for switching, an exhaust gas recirculation passage for flowing a part of the exhaust led out from the engine to the exhaust gas passage as exhaust gas recirculation gas to the intake air passage and recirculating to the engine, and the exhaust gas recirculation passage, Exhaust gas for adjusting the flow rate of the exhaust gas recirculation gas in the exhaust gas recirculation passage, including the air recirculation outlet, the exhaust gas recirculation inlet communicating with the exhaust passage, the exhaust gas recirculation outlet communicating with the intake air passage downstream of the intake air amount adjustment valve In an engine system including a recirculation valve and at least a control unit for controlling the flow path switching valve and the exhaust recirculation valve, a part of the high-temperature air introduced from the high-temperature air passage to the intake passage is diverted to the exhaust recirculation passage. The diversion passage and the diversion passage include a diversion inlet and a diversion outlet, the diversion inlet communicates with the intake passage downstream of the flow path switching valve and upstream of the intake air amount adjustment valve, and the diversion outlet is exhaust gas recirculation It is intended to include communication with the exhaust gas recirculation passage downstream of the valve and diversion adjusting means for adjusting the flow rate of high-temperature air in the diversion passage.

  According to the configuration of the invention described above, the control unit controls the flow path switching valve as necessary, and the flow path is switched, so that the intake air flowing downstream of the intake passage is exchanged with the high temperature air from the high temperature air path. It can be switched between cold air from the intake inlet. Therefore, the intake passage is warmed up by the high temperature air by switching the intake air to the high temperature air. A part of the high-temperature air flowing through the intake passage flows to the branch flow passage, is adjusted by the branch flow adjusting means, and is branched to the exhaust gas return passage downstream of the exhaust gas recirculation valve. Is done.

  To achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the engine is a reciprocating engine having a plurality of cylinders, and the intake passage distributes the intake air to each cylinder. The exhaust gas recirculation passage is branched into a plurality of branch passages immediately before the engine, and the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve includes an exhaust recirculation distribution pipe for distributing the exhaust gas recirculation gas flowing through the passage to the branch passages. Intended to be

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 1, the exhaust gas recirculation gas that has passed through the exhaust gas recirculation valve is distributed downstream to each branch passage of the intake air passage via the exhaust gas recirculation distribution pipe. Is done. Further, the high-temperature air that has been diverted from the diversion passage to the exhaust recirculation passage downstream of the exhaust recirculation valve flows through the exhaust recirculation diversion pipe, so that the same diversion pipe is warmed up.

  In order to achieve the above object, the invention described in claim 3 is that, in the invention described in claim 1, the diversion outlet of the diversion passage communicates with the exhaust recirculation passage in the vicinity of the exhaust recirculation valve. And

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 1, since the diversion outlet of the diversion passage communicates with the exhaust recirculation passage in the vicinity of the exhaust recirculation valve, the high temperature diverted to the exhaust recirculation passage Air heat is easily transmitted to the exhaust gas recirculation valve.

  In order to achieve the above object, the invention described in claim 4 is the invention described in claim 1, wherein the diversion adjusting means is an orifice for restricting the flow rate of high-temperature air.

  According to the configuration of the invention described above, in addition to the operation of the invention according to the first aspect, a small amount of high-temperature air is exhausted downstream of the exhaust gas recirculation valve via the shunt passage by a relatively simple orifice. It is always diverted to the reflux passage.

  In order to achieve the above object, according to a fifth aspect of the present invention, there is provided a bypass according to the fourth aspect of the present invention, wherein a bypass is provided between the intake passage near the intake air amount adjustment valve and the diversion passage downstream of the orifice. The purpose is to provide a passage.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 4, a part of the high-temperature air flowing in the intake passage near the intake air amount adjusting valve is passed through the bypass passage to the branch passage downstream of the orifice. And flow. Therefore, the amount of hot air that is diverted to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve increases by the amount of hot air that flows through the bypass passage.

  To achieve the above object, according to a sixth aspect of the present invention, in the fifth aspect of the present invention, the intake air amount adjustment valve includes a butterfly throttle valve, and the bypass passage includes a bypass inlet and a bypass outlet. In other words, the bypass inlet is disposed in the intake passage so as to be positioned downstream of the throttle valve when the throttle valve is closed and upstream of the throttle valve when the throttle valve is opened.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 4, when the throttle valve is closed, the inflow of high-temperature air to the bypass inlet is blocked. On the other hand, when the throttle valve is opened, hot air flows into the bypass inlet, and the hot air flows to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve via the bypass passage. Further, the flow rate of the high temperature air is adjusted according to the opening degree of the throttle valve.

  To achieve the above object, according to a seventh aspect of the present invention, in the sixth aspect of the present invention, the bypass outlet is disposed in the branch passage, and a check valve is provided in the branch passage downstream of the bypass outlet. The check valve is provided to open when the differential pressure before and after the pressure exceeds a predetermined value, and flow hot air downstream.

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 6, when the engine is operating at a high load, the intake negative pressure acting on the exhaust gas recirculation passage from the exhaust gas recirculation outlet is reduced, and the check valve is closed. The shunt passage is blocked. On the other hand, during low load operation of the engine, the intake negative pressure acting on the exhaust gas recirculation passage from the exhaust gas recirculation outlet becomes large, the differential pressure across the check valve becomes a predetermined value or more, the check valve opens, and the shunt passage Opened. Thereby, the flow of air from the diversion passage to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve is allowed.

  In order to achieve the above object, according to an eighth aspect of the present invention, in the first aspect of the present invention, the diversion adjusting means is an on-off valve that selectively opens and closes the diversion passage, and the control means is a high temperature The purpose is to control the opening and closing of the on-off valve when switching control of the flow path switching valve in order to flow high temperature air from the air passage to the downstream side of the intake passage.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, when the flow path switching valve is switched and high temperature air flows downstream of the intake passage, the opening / closing valve is controlled to open as necessary. The As a result, part of the high-temperature air is simultaneously diverted to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve via the diversion passage.

  In order to achieve the above object, the invention according to claim 9 is the invention according to claim 1, in which the accelerator operating means operated by the driver to request acceleration from the engine, and the operation of the accelerator operating means. And an accelerator detecting means for detecting the amount, the diversion adjusting means is a control valve for opening and closing the diversion passage in a variable opening, and the control means allows the high temperature air from the high temperature air passage to be downstream of the intake passage. The purpose is to control the opening of the control valve according to the detection value of the accelerator detection means when the flow path switching valve is controlled to flow to the side.

  According to the configuration of the invention described above, in addition to the operation of the invention according to claim 1, when high temperature air flows downstream of the intake passage, the opening degree of the control valve is controlled and a part of the high temperature air is distributed. The air is diverted to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve through the passage. Further, since the control valve is controlled with an opening degree corresponding to the degree of acceleration request to the engine, the amount of high-temperature air that is diverted to the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve is adjusted according to the acceleration request. . Therefore, in addition to the intake passage, the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve is warmed up with high accuracy according to the degree of acceleration request as required.

  In order to achieve the above object, according to a tenth aspect of the present invention, in the invention according to the eighth or ninth aspect, the control means supplies the high-temperature air to the exhaust gas recirculation passage downstream of the exhaust recirculation valve via the shunt passage. When permitting the opening of the exhaust gas recirculation valve, the target opening degree of the exhaust gas recirculation valve is corrected to be increased.

  According to the configuration of the invention, in addition to the action of the invention according to claim 8 or 9, when high-temperature air is diverted to the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve via the diversion passage, The pressure in the exhaust gas recirculation passage increases, and the differential pressure across the exhaust gas recirculation valve decreases. Therefore, when the opening of the exhaust gas recirculation valve is permitted, the flow rate of the exhaust gas recirculation gas flowing through the exhaust gas recirculation valve is reduced by the amount by which the differential pressure across the exhaust gas recirculation valve is reduced by the high-temperature air. In this configuration, when the opening of the exhaust gas recirculation valve is permitted, the target opening degree is corrected to increase, so that a decrease in the exhaust gas recirculation gas flow rate is compensated.

  In order to achieve the above object, according to an eleventh aspect of the present invention, in the invention according to the ninth aspect, the control means supplies the high-temperature air to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve via the diversion passage. When diverting, the target opening degree of the intake air amount adjusting valve is corrected to decrease in accordance with the detection value of the accelerator detection means.

  According to the configuration of the above invention, in addition to the action of the invention according to claim 9, when high-temperature air is diverted to the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve via the diversion passage, As a result, the amount of air flowing to the engine bypassing the intake air amount adjustment valve increases. In this configuration, when the intake air amount adjustment valve is opened, the target opening degree of the intake air amount adjustment valve is corrected to decrease in accordance with the detected value of the accelerator detection means. The amount of intake air to be adjusted is reduced.

  In order to achieve the above object, according to a twelfth aspect of the present invention, in the invention of the eighth aspect, the flow path switching valve fails in a state in which the low-temperature air from the intake inlet flows to the downstream side of the intake passage. A flow path switching valve failure diagnosis means for diagnosing this and a warm-up state detection means for detecting the warm-up state of the intake passage, and the control means The purpose is to reduce the target opening of the exhaust gas recirculation valve when the switching valve failure diagnostic means diagnoses and when it is determined that the intake passage has not been warmed up based on the detection result by the warm-up state detecting means. And

  According to the configuration of the invention described above, in addition to the operation of the invention according to claim 8, the control means diagnoses that the flow path switching valve is faulty by the flow path switching valve failure diagnostic means, and the warm-up state detection means. When it is determined that the intake passage is not warmed up based on the detection result, the target opening of the exhaust gas recirculation valve is corrected to decrease. Therefore, even when low-temperature air flows to the downstream side of the intake passage when it is cold, the flow rate of the exhaust gas recirculation gas to the intake passage can be kept small.

  In order to achieve the above object, the invention according to claim 13 is the invention according to claim 12, further comprising an intake air temperature detecting means for detecting the intake air temperature in the intake passage downstream of the flow path switching valve. The flow path switching valve failure diagnosing means is intended to diagnose a failure of the flow path switching valve based on the intake air temperature detected by the intake air temperature detecting means before and after the flow path switching valve is controlled to be switched.

  According to the configuration of the above invention, in addition to the action of the invention according to claim 12, when there is a change in the intake air temperature detected before and after the flow path switching valve is switched, the flow path switching valve operates normally. Therefore, switching between hot air and cold air has been performed normally. If there is no change in the detected intake air temperature, the flow path switching valve does not operate normally, and switching between high-temperature air and low-temperature air is not performed normally. The flow path switching valve failure diagnosing means diagnoses a failure of the flow path switching valve based on the presence or absence of a change in the intake air temperature detected by the intake air temperature detecting means before and after the flow path switching valve is switched.

  In order to achieve the above object, the invention described in claim 14 further comprises an on-off valve failure diagnosis means for diagnosing that the on-off valve has failed in the closed state in the invention described in claim 8. The control means is intended to reduce the target opening of the exhaust gas recirculation valve when the on-off valve failure diagnosis means diagnoses that the on-off valve is faulty.

  According to the configuration of the above invention, in addition to the action of the invention according to claim 8, when the on-off valve failure diagnosing means diagnoses that the on-off valve has failed in the closed state, the control means Correct the target opening by decreasing. Therefore, when the high-temperature air is not diverted to the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve when cold, the flow rate of the exhaust gas recirculation gas to that portion can be reduced.

  In order to achieve the above object, according to a fifteenth aspect of the present invention, in the fifteenth aspect of the present invention, there is provided an intake air amount detecting means for detecting an intake air amount flowing through the intake passage and a downstream of the intake air amount adjusting valve. Intake pressure detecting means for detecting the intake pressure in the intake passage, and the on-off valve failure diagnosis means before and after the on-off valve is controlled to open and close when the opening amount of the intake air amount adjustment valve is a predetermined condition The purpose is to diagnose a failure of the on-off valve based on the intake air amount detected by the intake air amount detection means and the intake pressure detected by the intake pressure detection means.

  According to the configuration of the above invention, in addition to the action of the invention according to claim 14, when the intake air amount and the intake pressure detected before and after the on-off valve is opened and closed, the on-off valve operated normally. It will be. On the other hand, when there is no change in the intake air amount and the intake pressure detected before and after the opening / closing valve is opened / closed, the opening / closing valve does not operate normally. The on-off valve failure diagnosing means is configured to detect the change in the intake air amount detected by the intake air amount detecting means and the intake pressure detecting means before and after the on-off valve is controlled to open and close when the opening degree of the intake air amount adjusting valve is a predetermined condition. A failure of the on-off valve is diagnosed based on the detected change in the intake pressure.

  According to the first aspect of the present invention, it is possible to suppress the generation of condensed water due to the exhaust gas recirculation gas in the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve in addition to the intake air passage during the cold time. Reflux can be performed.

  According to the second aspect of the present invention, in addition to the effect of the first aspect, the exhaust gas recirculation gas can be evenly supplied to each cylinder of the engine, and the exhaust gas recirculation pipe is warmed up. Thus, generation of condensed water due to the exhaust gas recirculation gas in the same distribution pipe can be suppressed.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1, the exhaust gas recirculation valve is warmed up by high-temperature air to suppress the generation of condensed water due to the exhaust gas recirculation gas in the exhaust gas recirculation valve. be able to.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 1, the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve can be warmed up at a relatively low cost, and the exhaust gas at that portion can be warmed up. The generation of condensed water due to the reflux gas can be suppressed.

  According to the fifth aspect of the invention, in addition to the effect of the fourth aspect of the invention, it is possible to warm up the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve in a shorter time than the configuration without the bypass passage. it can.

  According to the invention described in claim 6, in addition to the effect of the invention described in claim 5, when the throttle valve is opened, the high-temperature air is diverted to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve via the bypass passage. The amount of high-temperature air that is diverted to the exhaust gas recirculation passage can be increased accordingly. Also. The inflow of high-temperature air into the bypass passage can be adjusted without separately providing a dedicated adjusting means.

  According to the invention described in claim 7, in addition to the effect of the invention described in claim 6, it is possible to suppress a decrease in the differential pressure across the exhaust gas recirculation valve. Reduction of the reflux gas flow rate can be suppressed.

  According to the invention described in claim 8, in addition to the effect of the invention described in claim 1, in addition to the intake passage when cold, the exhaust recirculation gas in the exhaust recirculation passage downstream from the exhaust recirculation valve as necessary The generation of condensed water can be suppressed.

  According to the ninth aspect of the present invention, in addition to the effect of the first aspect, in addition to the intake passage when cold, the generation of condensed water by the exhaust recirculation gas in the exhaust recirculation passage downstream of the exhaust recirculation valve Can be suppressed with high accuracy.

  According to the invention of claim 10, in addition to the effect of the invention of claim 8 or 9, the exhaust gas recirculation that flows through the exhaust gas recirculation valve even when high-temperature air is diverted to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve. An appropriate amount of gas flow can be secured.

  According to the invention described in claim 11, in addition to the effect of the invention described in claim 9, even if high-temperature air flows to the engine via the shunt passage, the amount of air taken into the engine is appropriately set without excess or deficiency. Can be controlled.

  According to the twelfth aspect of the present invention, in addition to the effect of the eighth aspect of the invention, even if the flow path switching valve breaks down in a state where the low-temperature air flows to the intake passage in the cold state, Generation of condensed water due to the exhaust gas recirculation gas can be suppressed.

  According to the invention described in claim 13, in addition to the effect of the invention described in claim 12, a failure of the flow path switching valve can be detected relatively easily by using the intake air temperature detecting means.

  According to the fourteenth aspect of the present invention, in addition to the effect of the eighth aspect of the invention, the exhaust gas is exhausted in the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve even if the on-off valve is in a closed state when cold. The generation of condensed water due to the reflux gas can be suppressed.

  According to the invention of the fifteenth aspect, in addition to the effect of the invention of the fourteenth aspect, the failure of the on-off valve can be detected relatively easily by using the intake air amount detecting means and the intake pressure detecting means. it can.

1 is a schematic configuration diagram illustrating an engine system according to a first embodiment. The schematic diagram which concerns on 1st Embodiment and shows the relationship between each branch passage of EGR distribution piping and an intake manifold. The flowchart which concerns on 1st Embodiment and shows the content of EGR control. The flowchart which shows the content of EGR control in connection with 2nd Embodiment. The characteristic map referred in order to calculate the target control opening degree with respect to the accelerator opening degree according to the second embodiment. The characteristic map referred in order to calculate the target throttle opening with respect to 2nd Embodiment with respect to an accelerator opening. The flowchart which concerns on 3rd Embodiment and shows the content of intake air temperature control. The flowchart which concerns on 3rd Embodiment and shows the content of shunt control. The flowchart which shows the content of EGR control in connection with 3rd Embodiment. The schematic block diagram which concerns on 4th Embodiment and shows an engine system. The schematic structure figure showing an engine system concerning a 5th embodiment. The schematic structure figure showing an engine system concerning a 5th embodiment. Sectional drawing which concerns on 5th Embodiment and expands and shows the throttle valve vicinity of FIG. Sectional drawing which concerns on 5th Embodiment and expands and shows the throttle valve vicinity of FIG. Sectional drawing which concerns on 5th Embodiment and shows the shape of the branch inlet and bypass inlet in an intake passage. The schematic structure figure showing an engine system concerning a 6th embodiment. Sectional drawing which concerns on 6th Embodiment and expands and shows the non-return valve vicinity of FIG. The schematic diagram which concerns on another embodiment and shows the relationship between EGR distribution piping and each branch passage of an intake manifold.

<First Embodiment>
Hereinafter, a first embodiment of an engine system according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an engine system of this embodiment. In this embodiment, the engine 1 mounted on the automobile is a four-cycle reciprocating engine and includes four cylinders 2 and a crankshaft 3. The engine 1 is provided with an intake passage 4 for introducing intake air into the engine 1 and an exhaust passage 5 for leading exhaust from the engine 1. An air cleaner 6, an electronic throttle device 7, and an intake manifold 8 are provided in the intake passage 4 from the upstream side. The electronic throttle device 7 includes a butterfly throttle valve 9 that is driven to open and close by a motor 31 and a throttle sensor 41 for detecting an opening degree (throttle opening degree) TA of the throttle valve 9. The electronic throttle device 7 corresponds to an example of an intake air amount adjustment valve of the present invention for adjusting the intake air amount in the intake passage 4. Intake manifold 8 includes a surge tank 8 a and four branch passages 8 b that branch from surge tank 8 a to each cylinder 2 of engine 1. The exhaust passage 5 is provided with a catalytic converter 10 for purifying exhaust gas flowing through the passage 5. The catalytic converter 10 incorporates a three-way catalyst 10a made of a noble metal.

  The engine 1 includes a cylinder block 11 and a cylinder head 12. The cylinder block 11 includes each cylinder 2, and each cylinder 2 is provided with a piston 13. Each piston 13 is connected to the crankshaft 3 via a connecting rod 14. Each cylinder 2 includes a combustion chamber 15. The combustion chamber 15 is formed between the piston 13 and the cylinder head 12 in each cylinder 2. The cylinder head 12 is formed with an intake port 16 and an exhaust port 17 communicating with the combustion chamber 15 of each cylinder 2. Each intake port 16 communicates with the intake passage 4 (intake manifold 8). Each exhaust port 17 communicates with the exhaust passage 5. Each intake port 16 is provided with an intake valve 18, and each exhaust port 17 is provided with an exhaust valve 19. Each intake valve 18 and each exhaust valve 19 are interlocked with the rotation of the crankshaft 3, that is, interlocking with the vertical movement of each piston 13, and as a result, a series of operation strokes (intake stroke, compression stroke, The valve is driven to open and close by a valve mechanism including camshafts 20 and 21 in conjunction with an explosion stroke and an exhaust stroke. The intake valve 18 is driven to open and close by an intake camshaft 20, and the exhaust valve 19 is driven to open and close by an exhaust camshaft 21.

  The cylinder head 12 is provided with an injector 32 for injecting fuel to each intake port 16 corresponding to each cylinder 2. Each injector 32 is configured to inject fuel supplied from a fuel supply device (not shown). In each combustion chamber 15, a combustible air-fuel mixture is formed by the fuel injected from the injector 32 and the air sucked from the intake manifold 8 during the intake stroke or the like. In this embodiment, fuel is injected from the injector 32 when each cylinder 2 is in the exhaust stroke.

  The cylinder head 12 is provided with a spark plug 36 corresponding to each cylinder 2. Each spark plug 36 performs a spark operation in response to an ignition signal output from the ignition coil 37. Both parts 36 and 37 constitute an ignition device that ignites a combustible air-fuel mixture in each combustion chamber 15. The combustible air-fuel mixture in each combustion chamber 15 explodes and burns by the spark operation of each spark plug 36 in the compression stroke, and the explosion stroke passes. Exhaust gas after combustion is discharged from each combustion chamber 15 through the exhaust port 17, the exhaust passage 5, and the catalytic converter 10 in the exhaust stroke. As described above, the combustion of the combustible air-fuel mixture in each combustion chamber 15 causes each piston 13 to move up and down, a series of operation strokes progress, and the crankshaft 3 rotates, thereby obtaining power for the engine 1. In the engine 1, the crankshaft 3 rotates twice (720 ° A rotation) every time a series of operation strokes is completed once in each cylinder 2.

  In the engine 1, an exhaust gas recirculation device (a part of the exhaust gas led out from the combustion chamber 15 to the exhaust passage 5 flows into the intake passage 4 as exhaust gas recirculation gas (EGR gas) and recirculates to the combustion chamber 15 of each cylinder 2. EGR device) 51 is provided. The EGR device 51 includes an exhaust gas recirculation passage (EGR passage) 52 through which EGR gas flows, and an exhaust gas recirculation valve (EGR valve) 53 provided in the EGR passage 52 for adjusting the flow rate of the EGR gas in the EGR passage 52. The exhaust gas recirculation cooler (EGR cooler) 54 is provided in the EGR passage 52 and cools the EGR gas. The EGR valve 53 is an electrically operated valve that is electrically controlled so that the opening degree is variable, and corresponds to an example of the exhaust gas recirculation valve of the present invention. The EGR passage 52 is provided with a bypass passage 55 that bypasses the EGR cooler 54, and the bypass passage 55 is provided with a bypass valve 56 for controlling the flow of EGR gas. The bypass valve 56 is an electric valve whose opening degree is electrically controlled.

  The EGR passage 52 includes an exhaust gas recirculation inlet (EGR inlet) 52a and an exhaust gas recirculation outlet (EGR outlet) 52b. The EGR inlet 52 a is connected to the exhaust passage 5 downstream from the catalytic converter 10 and communicates with the exhaust passage 5. The EGR outlet 52b is connected to the intake manifold 8 (branch passage 8b) downstream of the electronic throttle device 7 and the surge tank 8a. In this embodiment, the EGR passage 52 downstream of the EGR valve 53 includes an EGR distribution pipe 57 attached to the intake manifold 8. The EGR outlet 52 b is also an outlet of the EGR distribution pipe 57. FIG. 2 schematically shows the relationship between the EGR distribution pipe 57 and each branch passage 8 b of the intake manifold 8. The EGR distribution pipe 57 is formed by branching into a tournament table, and its downstream end (EGR outlet 52b) is connected to each branch passage 8b. The reason why the downstream end of the EGR passage 52 is branched and connected to each branch passage 8b of the intake manifold 8 is to allow EGR gas to be evenly introduced into each branch passage 8b.

  In this embodiment, an intake air temperature control device 61 that selectively switches the intake air flowing through the intake passage 4 to high-temperature air and low-temperature air is provided as an accessory device of the engine 1. This device 61 includes a shroud 62 having a funnel shape for recovering high temperature air in the vicinity of the cylinder head 12 and around the exhaust passage 5 (exhaust manifold), and the high temperature air recovered by the shroud 62 is supplied to an air cleaner. 6 is provided with a high-temperature air passage 63 for introduction into the intake passage 4 upstream of 6 and a flow path switching valve 64 provided in the intake passage 4 on the upstream side of the air cleaner 6. The flow path switching valve 64 is connected to the tip of the high temperature air passage 63. In this embodiment, the exhaust passage 5 in the vicinity of the cylinder head 12 is used as the heating means of the present invention, and high-temperature air heated in the exhaust passage 5 flows into the high-temperature air passage 63. The flow path switching valve 64 is an electric valve, and includes a valve body 65 and a motor 66 that drives the valve body 65. The valve body 65 is switched between a low-temperature air position indicated by a solid line in FIG. 1 and a high-temperature air position indicated by a two-dot chain line in FIG. By disposing the valve body 65 at the low temperature air position, the high temperature air from the high temperature air passage 63 is blocked, and the outside air from the intake inlet 4a is introduced as low temperature air into the air cleaner 6 (low temperature air introduction). ). On the other hand, by disposing the valve body 65 at the high temperature air position, the low temperature air from the intake inlet 4a is blocked and the high temperature air from the high temperature air passage 63 is introduced into the air cleaner 6 (high temperature air introduction). ).

  According to the intake air temperature control device 61, when high-temperature air is introduced, warming up of the intake passage 4 including the intake manifold 8 can be promoted, and the generation of condensed water due to EGR gas in the intake passage 4 can be suppressed. On the other hand, when introducing low-temperature air, it is possible to maintain the optimum intake air temperature (40 to 50 ° C.), stabilize the oxygen density in the intake air, and improve the intake efficiency. Thereby, the combustion efficiency of the engine 1 can be improved and knock suppression of the engine 1 can be achieved.

  In this embodiment, a diversion passage 71 is provided between the intake passage 4 and the EGR passage 52 for diverting a part of the high temperature air introduced from the high temperature air passage 63 to the intake passage 4 to the EGR passage 52. It is done. The diversion passage 71 includes a diversion inlet 71a at one end and a diversion outlet 71b at the other end. The diversion inlet 71a communicates with the intake passage 4 downstream of the flow path switching valve 64 and the air cleaner 6 and upstream of the electronic throttle device 7, and the diversion outlet 71b is close to the EGR valve 53 and downstream of the EGR valve 53 and EGR. The EGR passage 52 communicates upstream of the distribution pipe 57. The diversion passage 71 is provided with an on-off valve 72 for adjusting the flow rate of high-temperature air in the passage 71. The on-off valve 72 is an electric valve and selectively opens and closes the diversion passage 71. The on-off valve 72 corresponds to an example of a flow dividing adjusting unit of the present invention.

  As shown in FIG. 1, various sensors 41 to 48 provided in the engine 1 constitute an operation state detection unit for detecting the operation state of the engine 1. An accelerator sensor 42 is provided on the accelerator pedal 27 provided in the driver's seat. The accelerator pedal 27 corresponds to an example of an accelerator operating means of the present invention that is operated by the driver to request the engine 1 to accelerate. The accelerator sensor 42 detects a depression angle, which is an operation amount of the accelerator pedal 27, as an accelerator opening ACC, and outputs an electric signal corresponding to the detected value. The accelerator sensor 42 corresponds to an example of an accelerator detection unit of the present invention. The water temperature sensor 43 provided in the engine 1 detects the temperature (cooling water temperature) THW of the cooling water flowing through the water jacket 11a formed in the cylinder block 11 and outputs an electric signal corresponding to the detected value. A rotational speed sensor 44 provided in the engine 1 detects a rotational speed (engine rotational speed) NE of the crankshaft 3 and outputs an electrical signal corresponding to the detected value. The sensor 44 is configured to detect the rotation of the timing rotor 28 fixed to one end of the crankshaft 3 for each predetermined angle. An air flow meter 45 provided in the intake passage 4 upstream from the electronic throttle device 7 detects the intake air amount Ga flowing through the intake passage 4 and outputs an electric signal corresponding to the detected value. The air flow meter 45 corresponds to the intake air amount detection means of the present invention. The oxygen sensor 46 provided in the exhaust passage 5 detects the oxygen concentration (output voltage) Ox in the exhaust led to the exhaust passage 5 and outputs an electrical signal corresponding to the detected value. The intake air temperature sensor 47 provided in the air cleaner 6 detects the intake air temperature THA in the intake passage 4 downstream from the flow path switching valve 64 and outputs an electrical signal corresponding to the detected value. The intake air temperature sensor 47 corresponds to an example of the intake air temperature detection means of the present invention. The intake pressure sensor 48 provided in the surge tank 8a detects the intake pressure PM in the intake passage 4 downstream from the electronic throttle device 7, and outputs an electrical signal corresponding to the detected value. The intake pressure sensor 48 corresponds to an example of the intake pressure detection means of the present invention.

  The engine system includes an electronic control unit (ECU) 50 for controlling the operation of the engine 1. Various sensors 41 to 48 are connected to the ECU 50. The ECU 50 is connected to the motor 31 of the electronic throttle device 7, the injectors 32, the ignition coils 37, the EGR valve 53, the bypass valve 56, and the flow path switching valve 64. The ECU 50 corresponds to an example of a control unit of the present invention.

  In this embodiment, the ECU 50 performs the fuel injection control, the ignition timing control, the EGR control, and the like based on the output signals from the various sensors 41 to 48, and the motor 31, the injectors 32, the ignition coils 37, the EGR valve. 53, the bypass valve 56 and the motor 66 are controlled.

  Here, the fuel injection control is to control the fuel injection amount and the injection timing by each injector 32 in accordance with the operating state of the engine 1. The ignition timing control is to control the ignition timing by each spark plug 33 by controlling each ignition coil 37 according to the operating state of the engine 1. The EGR control is to control the EGR flow rate recirculated to each combustion chamber 15 by controlling the EGR valve 53 and the bypass valve 56 according to the operating state of the engine 1.

  As is well known, the ECU 50 includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like. The memory stores a predetermined control program related to various controls of the engine 1. The CPU executes the various controls described above based on a predetermined control program based on the detection signals of the various sensors 41 to 48 input via the input circuit.

  Next, the contents of EGR control in this embodiment will be described in detail. FIG. 3 is a flowchart showing the contents of the EGR control. The ECU 50 starts processing of this routine simultaneously with the start of the engine 1.

  When the process proceeds to this routine, in step 100, the ECU 50 takes in the starting coolant temperature STHW and the starting intake air temperature STHA when the engine 1 is started based on the detected values of the water temperature sensor 43 and the intake air temperature sensor 47, respectively. .

  Next, in step 110, the ECU 50 takes in the engine rotational speed NE and the engine load KL based on the detection values of the rotational speed sensor 44 and the intake pressure sensor 48, respectively.

  Next, in step 120, the ECU 50 takes in the coolant temperature THW and the intake air temperature THA based on the detection values of the water temperature sensor 43 and the intake air temperature sensor 47, respectively.

  Next, at step 130, the ECU 50 calculates a target EGR opening degree Tegr from the taken-in cooling water temperature THW, engine speed NE, and engine load KL. For example, the ECU 50 can calculate the target EGR opening degree Tegr by referring to a preset characteristic map.

  Next, in step 140, the ECU 50 performs a high-temperature air introduction determination. That is, the ECU 50 determines whether or not to introduce high-temperature air based on the taken-in start-up coolant temperature STHW and start-up intake air temperature STHA. For example, when the start-time cooling water temperature STHW and the start-time intake air temperature STHA are low, it is determined that high-temperature air introduction should be executed. “Execution of introduction of high-temperature air” refers to execution of introduction of high-temperature air into the intake passage 4 by switching the valve body 65 of the flow path switching valve 64 to a high-temperature air position, as will be described later. The ECU 50 proceeds to step 150 when the determination result is affirmative, and proceeds to step 240 when the determination result is negative.

  In step 150, the ECU 50 reads the integrated intake air amount IGa after execution of high-temperature air introduction. The ECU 50 separately calculates the integrated intake air amount IGa.

  Next, at step 160, the ECU 50 determines whether or not the integrated intake air amount IGa is less than a predetermined value A1. The ECU 50 proceeds to step 170 when the determination result is affirmative, and proceeds to step 240 when the determination result is negative.

  In step 170, the ECU 50 executes hot air introduction. That is, the ECU 50 introduces the high-temperature air into the intake passage 4 by switching the valve body 65 of the flow path switching valve 64 to the high-temperature air position. Thereby, before the EGR valve 53 opens, the intake passage 4 is warmed up by the high-temperature air.

  Next, in step 180, the ECU 50 controls the opening / closing valve 72 to open. As a result, the high-temperature air introduced into the intake passage 4 is diverted to the EGR passage 52 (including the EGR distribution pipe 57; the same applies hereinafter) downstream of the EGR valve 53 via the diversion passage 71. Thereby, prior to opening of the EGR valve 53, the EGR passage 52 downstream of the EGR valve 53 is warmed up by the high-temperature air. Further, by introducing high-temperature air (fresh air) into the EGR distribution pipe 57, the EGR gas in the distribution pipe 57 is diluted, and the dew point temperature of the moisture in the EGR gas is lowered.

  Next, at step 190, the ECU 50 once controls the electronic throttle device 7 to a predetermined idle opening.

  Next, in step 200, the ECU 50 corrects the opening of the electronic throttle device 7 to the closed side by the amount of hot air introduced. That is, since high-temperature air is introduced into the intake passage 4 (including the intake manifold 8) via the diversion passage 71 and the EGR passage 52, the throttle of the electronic throttle device 7 is anticipated in consideration of the amount of air introduced. The opening degree of the valve 9 is corrected to the closing side.

  Next, in step 210, the ECU 50 calculates the corrected target EGR opening KTegr by multiplying the currently calculated target EGR opening Tegr by the high-temperature air correction value Kht. Here, the high-temperature air correction value Kht is a value larger than “1.0”, and is set so that the corrected target EGR opening degree KTegr becomes larger than the target EGR opening degree Tegr. This is because high-temperature air is introduced from the diversion passage 71 to the EGR passage 52, so that the differential pressure across the EGR valve 53 decreases and the amount of EGR gas flowing through the EGR valve 53 decreases. Therefore, in order to compensate for this decrease, the opening degree of the EGR valve 53 is corrected to increase.

  Next, in step 220, the ECU 50 sets the corrected target EGR opening degree KTegr as the final target EGR opening degree TEGR.

  In step 230, the ECU 50 controls the EGR valve 53 to the final target EGR opening degree TEGR and returns the process to step 100.

  On the other hand, in step 240 after shifting from step 140 or step 160, the ECU 50 executes low-temperature air introduction. That is, the ECU 50 introduces low-temperature air (air at an outside air temperature) into the intake passage 4 by switching the valve body 65 of the flow path switching valve 64 to the low-temperature air position.

  Next, in step 250, the ECU 50 controls the opening / closing valve 72 to close. As a result, the flow of the low-temperature air introduced into the intake passage 4 into the branch passage 71 is blocked.

  Next, in step 260, the ECU 50 controls the electronic throttle device 7 to a predetermined idle opening.

  Next, at step 270, the ECU 50 sets the target EGR opening degree Tegr as the final target EGR opening degree TEGR.

  In step 230, the ECU 50 controls the EGR valve 53 to the final target EGR opening degree TEGR and returns the process to step 100.

  According to the above control, the ECU 50 allows the high-temperature air from the high-temperature air passage 63 to flow downstream of the intake passage 4 (including the electronic throttle device 7 and the intake manifold 8; the same applies hereinafter). When the 64 valve bodies 65 are controlled to be switched to the high temperature air position, the opening / closing valve 72 is controlled to open. In addition, when the ECU 50 divides the high-temperature air into the EGR passage 52 downstream of the EGR valve 53 via the diversion passage 71 and permits the opening of the EGR valve 53, the ECU 50 sets the target EGR opening degree Tegr. The amount of increase is corrected.

  According to the engine system of this embodiment described above, the high temperature air heated by the exhaust passage 5 is guided to the intake passage 4 through the shroud 62 and the high temperature air passage 63. Here, the ECU 50 controls the flow path switching valve 64 as necessary, and the flow path is switched by the flow path switching valve 64 so that the intake air flowing downstream of the intake passage 4 is heated from the high temperature air passage 63. It is switched between air and cold air from the intake inlet 4a. Therefore, the intake passage 4 is warmed up by the high temperature air by switching the intake air to the high temperature air. A part of the high-temperature air flowing through the intake passage 4 flows to the branch passage 71 when the on-off valve 72 is opened, and is branched to the EGR passage 52 downstream from the EGR valve 53, and the EGR passage 52 in that portion is hot. Warmed up by air. For this reason, it is possible to suppress the generation of condensed water due to EGR gas in the EGR passage 52 downstream of the EGR valve 53 in addition to the intake passage 4 when cold. As a result, EGR can be executed early when cold.

  In this embodiment, when the flow path switching valve 64 is switched and high-temperature air flows downstream of the intake passage 4, the opening / closing valve 72 is controlled to open as necessary. Thereby, part of the high-temperature air is simultaneously diverted to the EGR passage 52 downstream of the EGR valve 53 via the diversion passage 71. Thereby, in addition to the intake passage 4, the EGR passage 52 downstream from the EGR valve 53 is warmed up as necessary. For this reason, it is possible to suppress the generation of condensed water due to EGR gas in the EGR passage 52 downstream of the EGR valve 53 as needed in addition to the intake passage 4 when cold.

  In this embodiment, the EGR gas that has passed through the EGR valve 53 is distributed downstream to the respective branch passages 8 b of the intake manifold 8 via the EGR distribution pipe 57. Further, the high-temperature air that is diverted from the diversion passage 71 to the EGR passage 52 downstream of the EGR valve 53 flows through the EGR distribution pipe 57, so that the same distribution pipe 57 is warmed up. For this reason, EGR gas can be uniformly supplied to each cylinder 2 of the engine 1, and the generation of condensed water due to EGR gas in the same distribution pipe 57 can be suppressed by warming up the EGR distribution pipe 57 at the same time. it can.

  In this embodiment, the diversion outlet 71 b of the diversion passage 71 communicates with the EGR passage 52 in the vicinity of the EGR valve 53, so that the heat of the high-temperature air diverted to the EGR passage 52 is easily transmitted to the EGR valve 53. For this reason, the EGR valve 53 can be warmed up by the high-temperature air, and the generation of condensed water due to the EGR gas in the EGR valve 53 can be suppressed.

  In this embodiment, when the high-temperature air is diverted to the EGR passage 52 downstream from the EGR valve 53 via the diversion passage 71, the pressure in the EGR passage 52 in that portion increases due to the high-temperature air, and before and after the EGR valve 53. The differential pressure is reduced. Therefore, when the opening of the EGR valve 53 is permitted, the flow rate of the EGR gas passing through the EGR valve 53 is reduced by the amount that the differential pressure across the EGR valve 53 is reduced by the high-temperature air. In the above configuration, when the opening of the EGR valve 53 is permitted, the target EGR opening degree Tegr is corrected to increase by the high-temperature air correction value Kht, so that the decrease in the EGR gas flow rate is compensated. For this reason, even if high-temperature air is diverted to the EGR passage 52 downstream from the EGR valve 53, an appropriate amount of EGR gas flow through the EGR valve 53 can be ensured.

Second Embodiment
Next, a second embodiment in which the engine system of the present invention is embodied will be described in detail with reference to the drawings.

  In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described.

  This embodiment is different from the first embodiment in the configuration of the diversion adjusting means of the present invention and the contents of EGR control. That is, in this embodiment, in FIG. 1, a control valve 74 that opens and closes the diversion passage 71 with a variable opening is provided in the diversion passage 71 instead of the on-off valve 72 provided in the first embodiment. .

  Next, the contents of EGR control in this embodiment will be described in detail. FIG. 4 is a flowchart showing the contents of the EGR control. In the flowchart of FIG. 4, Step 300 is provided between Step 120 and Step 130, Steps 310 to 340 are provided instead of Steps 180 to 200, and Steps 350 to 370 are provided instead of Steps 250 and 260. 3 is different from the flowchart of FIG.

  When the processing shifts to this routine, the ECU 50 executes the processing of steps 100 to 120 and then takes in the accelerator opening ACC based on the detection value of the accelerator sensor 42 in step 300.

  Thereafter, the ECU 50 executes the processing of steps 130 to 170, and then calculates the target control opening TCV corresponding to the accelerator opening ACC in step 310. The target control opening TCV is a target opening related to the control valve 74. For example, the ECU 50 can calculate the target control opening degree TCV with respect to the accelerator opening degree ACC by referring to a characteristic map as shown in FIG. In FIG. 5, the thick broken line indicates the characteristics when the high temperature air is introduced, and the thick line indicates the characteristics when the low temperature air is introduced. In this characteristic map, when high-temperature air is introduced, the target control opening TCV increases from the fully closed state to the predetermined value P1 until the accelerator opening degree ACC reaches the predetermined value P1, and the target control opening degree TCV is larger than the predetermined value P1. It becomes constant when fully open.

  Next, at 320, the ECU 50 controls the control valve 74 to the target control opening TCV. Thereby, the control valve 74 is opened at an opening degree corresponding to the accelerator opening degree ACC in preference to the opening of the electronic throttle device 7.

  Next, in step 330, the ECU 50 calculates a target throttle opening degree TSV corresponding to the accelerator opening degree ACC. The target throttle opening degree TSV is a target opening degree related to the throttle valve 9 of the electronic throttle device 7. For example, the ECU 50 can calculate the target throttle opening degree TSV with respect to the accelerator opening degree ACC by referring to a characteristic map as shown in FIG. In FIG. 6, the thick broken line indicates the characteristics when the high temperature air is introduced, and the thick line indicates the characteristics when the low temperature air is introduced. In this characteristic map, when high-temperature air is introduced, the target throttle opening TSV gradually increases until the accelerator opening ACC reaches the predetermined value P1 from the fully closed state. At an opening larger than the predetermined value P1, the target throttle opening TSV is After increasing rapidly, the rate of increase is slightly reduced. Therefore, in this embodiment, as shown in FIGS. 5 and 6, while the accelerator opening ACC is increased from the fully closed state to the predetermined value P1, the control valve 74 is prior to the electronic throttle device 7 being opened. Open to fully open. In other words, the supply of high-temperature air (fresh air) supplied from the electronic throttle device 7 to the intake manifold 8 is suppressed by the amount of high-temperature air (new air) supplied from the branch passage 71 to the intake manifold 8. That is, when the ECU 50 switches and controls the flow path switching valve 64 in order to flow high temperature air downstream (intake manifold 8) of the intake passage 4, the target throttle opening of the electronic throttle device 7 is opened according to the accelerator opening ACC. The degree TSV is once corrected for reduction.

  Next, in step 340, the ECU 50 controls the electronic throttle device 7 to the target throttle opening degree TSV. As a result, the electronic throttle device 7 opens at an opening degree corresponding to the accelerator opening degree ACC after the control valve 74 is opened. Thereafter, the ECU 50 executes the processes of steps 210 to 230, and then returns the process to step 100.

  On the other hand, after executing the processing of step 240, the ECU 50 controls the control valve 74 to be fully closed in step 350. Thereby, the branching of the low-temperature air introduced into the intake passage 4 to the branch passage 71 is blocked.

  Next, at step 360, the ECU 50 calculates a target throttle opening degree TSV corresponding to the accelerator opening degree ACC.

  Next, in step 370, the ECU 50 controls the electronic throttle device 7 to the calculated target throttle opening degree TSV. Thereafter, ECU 50 executes the processes of steps 270 and 230, and then returns the process to step 100.

  According to the above control, unlike the first embodiment, the ECU 50 controls the opening degree of the control valve 74 according to the accelerator opening degree ACC when the valve body 65 of the flow path switching valve 64 is controlled to be switched to the high temperature air position. It comes to control. At this time, the ECU 50 controls the opening of the control valve 74 in preference to the valve opening control of the electronic throttle device 7 in order to maximize the warm-up effect of the hot air on the EGR distribution pipe 57.

  According to the engine system of this embodiment described above, basically the same operational effects as those of the first embodiment can be obtained, but the following operational effects can be obtained depending on the difference in configuration. That is, in this embodiment, when the flow switching valve 64 is switched and high temperature air flows to the downstream side of the intake passage 4, the opening degree of the control valve 74 is controlled and a part of the high temperature air passes through the diversion passage 71. Through the EGR valve 53 to the EGR passage 52 downstream. Further, since the control valve 74 is controlled at an opening degree corresponding to the degree of the driver's acceleration request (accelerator opening degree ACC) with respect to the engine 1, the amount of high-temperature air diverted to the EGR passage 52 downstream from the EGR valve 53. Is adjusted according to the accelerator opening ACC. Therefore, in addition to the intake passage 4, the EGR passage 52 downstream from the EGR valve 53 is warmed up with high accuracy according to the degree of acceleration request to the engine 1 as necessary. For this reason, it is possible to accurately suppress the generation of condensed water due to EGR gas in the EGR passage 52 downstream of the EGR valve 53 in addition to the intake passage 4 when cold.

  In this embodiment, when high-temperature air is diverted to the EGR passage 52 downstream from the EGR valve 53 via the diversion passage 71, the engine bypasses the electronic throttle device 7 by the amount of the high-temperature air that is diverted. The amount of air flowing to 1 will increase. According to the above configuration, when the electronic throttle device 7 is opened, the target throttle opening TSV of the electronic throttle device 7 is corrected to decrease in accordance with the accelerator opening ACC. The intake air amount adjusted by the device 7 is reduced. For this reason, even if high-temperature air flows to the engine 1 via the branch flow path 71, the air taken into the engine 1 can be controlled to an appropriate amount without excess or deficiency.

  In this embodiment, the high-temperature air flowing to the engine 1 is preferentially diverted to the EGR distribution pipe 57 via the diversion passage 71 without taking heat away by the electronic throttle device 7 or the intake manifold 8. Therefore, the inner wall of the EGR distribution pipe 57 can be warmed up early, and the EGR gas in the same distribution pipe 57 can be diluted with high-temperature air. As a result, the generation of condensed water due to the EGR gas in the EGR distribution pipe 57 can be further suppressed.

<Third Embodiment>
Next, a third embodiment of the engine system according to the present invention will be described in detail with reference to the drawings.

  In each of the above-described embodiments, the EGR distribution pipe 57 can be warmed up early by diverting high-temperature air to the EGR distribution pipe 57 when it is cold, so that EGR can be executed early. However, there are cases where the flow path switching valve 64 fails and high-temperature air cannot flow downstream of the intake passage 4. Alternatively, the on-off valve 72 or the control valve 74 may fail and the high-temperature air may not be diverted to the EGR distribution pipe 57. In these cases, if EGR is executed early assuming that the warm-up of the downstream side of the intake passage 4 and the EGR distribution pipe 57 has been completed early, condensed water is generated by EGR gas inside the intake manifold 8 and the EGR distribution pipe 57. May occur. Therefore, in this embodiment, the ECU 50 executes the following control in order to cope with the above-described failure.

  FIG. 7 is a flowchart showing the content of switching control (intake air temperature control) between high-temperature air introduction and low-temperature air introduction into the intake passage 4.

  When the process proceeds to this routine, in step 400, the ECU 50 determines whether or not the engine 1 has been started. The ECU 50 can make this determination based on the detection value of the rotation speed sensor 44. The ECU 50 proceeds to step 410 when the determination result is affirmative, and proceeds to step 520 when the determination result is negative.

  In step 410, the ECU 50 takes in the starting intake air temperature STHA when the engine 1 is started based on the detected value of the intake air temperature sensor 47.

  Next, in step 420, the ECU 50 determines whether or not the taken intake air temperature STHA is lower than a predetermined value TH1. As this predetermined value TH1, for example, “50 ° C.” can be applied. The ECU 50 proceeds to step 430 when the determination result is affirmative, and proceeds to step 540 when the determination result is negative.

  In step 430, the ECU 50 determines whether or not the flow path switching failure detection flag XHAO is “0”. As will be described later, the flag XHAO is set to “0” when failure detection of the flow path switching valve 64 is not completed and to “1” when failure detection is completed. The ECU 50 proceeds to step 440 when this determination result is affirmative, and returns the process to step 400 when this determination result is negative.

  In step 440, the ECU 50 switches the flow path switching valve 64 to the high temperature air position.

  Next, in step 450, the ECU 50 waits for a predetermined time T1 to elapse after switching the flow path switching valve 64 to the high temperature air position, and proceeds to step 460. For example, “30 seconds” can be applied as the predetermined time T1.

  In step 460, the ECU 50 takes in the intake air amount Ga based on the detection value of the air flow meter 45.

  Next, at step 470, the ECU 50 determines whether or not the intake air amount Ga taken in is less than a predetermined value G1. As this predetermined value G1, an intake air amount corresponding to the low load operation of the engine 1 can be applied. The ECU 50 proceeds to step 480 when the determination result is affirmative, and returns to step 400 when the determination result is negative.

  In step 480, the ECU 50 takes in the current intake air temperature THA based on the detected value of the intake air temperature sensor 47.

  Next, at step 490, the ECU 50 determines whether or not the starting intake air temperature STHA is lower than a temperature obtained by adding a predetermined value α to the current intake air temperature THA. Here, for example, “30 ° C.” can be applied as the predetermined value α. The ECU 50 proceeds to step 500 when this determination result is affirmative, and proceeds to step 550 when this determination result is negative.

  In step 500, the ECU 50 determines that the flow path switching valve 64 is operating normally. In this case, the flow path switching valve 64 is normally switched to the high temperature air position. The ECU 50 can store the determination result in a built-in memory.

  Next, in step 510, since the failure detection of the flow path switching valve 64 has been completed, the ECU 50 sets the flow path switching failure detection flag XHAO to “1” and returns the process to step 400.

  On the other hand, after shifting from step 400, in step 520, the ECU 50 sets the flow path switching failure detection flag XHAO to “0”. Alternatively, in step 540 after proceeding from step 420, the ECU 50 sets the flow path switching failure detection flag XHAO to “1”.

  In step 530 after shifting from step 520 or step 540, the ECU 50 switches the flow path switching valve 64 to the low temperature air position, and then returns the process to step 400.

  On the other hand, the process proceeds from step 490, and in step 550, it is determined whether or not the starting intake air temperature STHA is lower than the current intake air temperature THA plus a predetermined value β. Here, for example, “10 ° C.” can be applied as the predetermined value β. The ECU 50 proceeds to step 560 when the determination result is affirmative, and returns the process to step 400 when the determination result is negative.

  In step 560, the ECU 50 determines that the flow path switching valve 64 is abnormal. In this case, the flow path switching valve 64 is not normally switched to the high temperature air position. The ECU 50 can store the determination result in a built-in memory.

  Next, in step 570, the ECU 50 notifies that the flow path switching valve 64 is abnormal. For example, the ECU 50 can notify this abnormality by blinking an alarm lamp (not shown). Thereafter, the ECU 50 proceeds to step 510.

  In the above configuration, the ECU 50 causes the flow path switching valve 64 to malfunction while the low-temperature air from the intake inlet 4a is allowed to flow to the downstream side of the intake passage 4, that is, the valve body 65 is disposed at the low-temperature air position. This corresponds to an example of the flow path switching valve failure diagnosis means of the present invention for diagnosing this. According to the above control, the ECU 50 is before and after the flow path switching valve 64 is switched, that is, before and after the valve element 65 of the flow path switching valve 64 is switched between the high temperature air position and the low temperature air position. The failure of the flow path switching valve 64 is diagnosed based on the intake air temperature THA detected by the intake air temperature sensor 47.

  FIG. 8 is a flow chart showing the content of (diversion control) related to the diversion of high-temperature air to the diversion passage 71.

  When the process proceeds to this routine, in step 600, the ECU 50 determines the throttle opening TA, the throttle opening change ΔTA, the intake air amount Ga, and the intake pressure PM based on the detected values of the throttle sensor 41, the air flow meter 45, and the intake pressure sensor 48. Each.

  Next, at step 610, the ECU 50 determines whether or not the throttle opening degree TA is larger than a predetermined value B1. The predetermined value B1 assumes an upper limit value of the idle opening, and in this step 610, the ECU 50 determines whether or not the engine 1 is in an operating state other than the idle operation. The ECU 50 proceeds to step 620 when the determination result is affirmative, and proceeds to step 760 when the determination result is negative.

  Next, in step 620, the ECU 50 determines whether or not the throttle opening degree TA is larger than a predetermined value D1 (D1> B1). The predetermined value D1 assumes normal operation of the engine 1, and in this step 620, the ECU 50 determines whether or not the engine 1 is in a normal operation state. The ECU 50 proceeds to step 630 when this determination result is affirmative, and returns the process to step 600 when this determination result is negative.

  Next, at step 630, the ECU 50 determines whether or not the throttle opening change ΔTA is smaller than a predetermined value E1. The predetermined value E1 assumes acceleration operation of the engine 1, and in this step 630, the ECU 50 determines whether or not the engine 1 is in a steady operation state. The ECU 50 proceeds to step 640 when this determination result is affirmative, and returns the process to step 600 when this determination result is negative.

  In step 640, the ECU 50 determines whether or not the valve closing flag XSVC is “0”. The flag XSVC is set to “1” when the on-off valve 72 of the flow dividing passage 71 is closed as will be described later. The ECU 50 proceeds to step 650 when the determination result is affirmative, and proceeds to step 680 when the determination result is negative.

  In step 650, the ECU 50 controls the on-off valve 72 to close. As a result, the flow of hot air to the flow dividing passage 71 is blocked.

  Next, at step 660, the ECU 50 takes in the intake air amount Ga when the on-off valve 72 is closed as the closed valve intake air amount Gac based on the detected value of the air flow meter 45. Further, the engine 50 takes in the intake pressure PM when the on-off valve 72 is closed based on the detected value of the intake pressure sensor 48 as the closed valve intake pressure PMc.

  Next, in step 670, the ECU 50 sets the valve closing flag XSVC to “1”, and then returns the process to step 640.

  On the other hand, in step 680 after shifting from step 640, the ECU 50 controls the opening / closing of the on-off valve 72. Thereby, the branching of the high temperature air to the branch passage 71 is permitted.

  Next, at step 690, the ECU 50 takes in the intake air amount Ga when the on-off valve 72 is open as the valve open intake air amount Gao based on the detection value of the air flow meter 45. Further, the engine 50 takes in the intake pressure PM when the on-off valve 72 is open as the valve-open intake pressure PMo based on the detection value of the intake pressure sensor 48.

  Next, at step 700, the ECU 50 determines that the difference between the valve opening intake air amount Gao and the valve closing intake air amount Gac is not less than a predetermined value F1, and that the difference between the valve opening intake air pressure PMo and the valve closing intake air pressure PMc is predetermined. It is determined whether or not the value is greater than or equal to G1. That is, in this step 700, the ECU 50 determines whether or not the intake air amount Ga and the intake pressure PM have changed when the opening and closing of the on-off valve 72 is switched. The ECU 50 proceeds to step 710 when the determination result is affirmative, and proceeds to step 720 when the determination result is negative.

  In step 710, since there is a change in each of the intake air amount Ga and the intake pressure PM, and the on-off valve 72 is considered to have operated normally, the ECU 50 determines that the on-off valve 72 is normal, and then the processing is step 600. Return to. The ECU 50 can store the normality determination result in a built-in memory.

  On the other hand, in step 720, since it is considered that at least one of the intake air amount Ga and the intake pressure PM has not changed and the on-off valve 72 has not operated normally, the ECU 50 determines that the on-off valve 72 is abnormal, and thereafter The process returns to step 600.

  Next, in step 730, the ECU 50 determines whether or not the valve closing normal flag XNC is “1”. As will be described later, this flag XNC is set to “1” when it is determined that the on-off valve 72 is closed when the engine 1 is in the idling operation state. The ECU 50 proceeds to step 740 when the determination result is affirmative, and proceeds to step 750 when the determination result is negative.

  In step 740, the ECU 50 determines that the on-off valve 72 is abnormally closed (abnormal while remaining closed), and returns the process to step 600. The ECU 50 can store the abnormality determination result in a built-in memory or perform a predetermined notification operation.

  In step 750, the ECU 50 determines that the opening / closing valve 72 is abnormal in opening (it is abnormal in the opened state), and returns the process to step 600. The ECU 50 can store the abnormality determination result in a built-in memory or perform a predetermined notification operation.

  On the other hand, in step 760 after the transition from step 610, the ECU 50 controls the on-off valve 72 to be closed when the engine 1 is in an idle operation state.

  Next, in step 770, the ECU 50 determines whether or not the taken-in intake air amount Ga is greater than a predetermined value H1. This predetermined value H1 assumes a value larger than the normal intake air amount that flows during idle operation. The ECU 50 proceeds to step 780 when the determination result is affirmative, and proceeds to step 790 when the determination result is negative.

  In step 780, the ECU 50 determines that the on-off valve 72 is abnormal in opening (abnormal in the open state) because an intake air amount Ga larger than expected flows through the intake passage 4 regardless of the idling operation state. Then, the process returns to step 600. The ECU 50 can store the abnormality determination result in a built-in memory or perform a predetermined notification operation.

  On the other hand, in step 790, the ECU 50 determines whether or not the taken-in intake air amount Ga is smaller than a predetermined value J1. This predetermined value J1 assumes a normal intake amount that flows during idle operation. The ECU 50 proceeds to step 800 when the determination result is affirmative, and returns the process to step 600 when the determination result is negative.

  In step 800, the ECU 50 determines that the on-off valve 72 is normally closed (normal in the closed state) because the intake air amount Ga assumed in the idling operation state flows through the intake passage 4, and described above. The valve closing normal flag XNC is set to “1”, and the process returns to step 600. The ECU 50 can store the normality determination result in a built-in memory.

  According to the above configuration, the ECU 50 corresponds to an example of the on-off valve failure diagnosis means of the present invention for diagnosing that the on-off valve 72 has failed in the closed state. According to the above control, the ECU 50 controls the intake air amount Ga and the intake pressure PM detected before and after the on-off valve 72 is controlled to open and close when the throttle opening degree TA of the electronic throttle device 7 is a predetermined condition. A failure of the on-off valve 72 is diagnosed based on the change.

  Next, EGR control will be described. FIG. 9 is a flowchart showing the contents of EGR control in this embodiment. When the process proceeds to this routine, in step 900, the ECU 50 takes in the coolant temperature THW, the engine rotational speed NE, and the engine load KL based on the detected values of the water temperature sensor 43, the rotational speed sensor 44, and the intake pressure sensor 48, respectively. .

  Next, in step 910, the ECU 50 calculates a target EGR opening degree Tegr from the taken-in engine rotational speed NE and engine load KL. For example, the ECU 50 can calculate the target EGR opening degree Tegr by referring to a predetermined characteristic map.

  Next, at step 920, the ECU 50 determines whether or not the flow path switching valve 64 is abnormal at the low temperature air position, that is, whether or not the valve body 65 is stuck at the low temperature air position. The ECU 50 can make this determination by referring to the abnormality determination in the routine shown in FIG. The ECU 50 proceeds to step 930 when the determination result is affirmative, and proceeds to step 960 when the determination result is negative.

  In step 930, ECU 50 determines whether or not the taken-in cooling water temperature THW is lower than a predetermined value TH1. Here, the predetermined value TH1 is a value indicating that the intake passage 4 is in a warm-up state, and for example, “70 ° C.” can be applied. The ECU 50 proceeds to step 940 when the determination result is affirmative, and proceeds to step 980 when the determination result is negative.

  In step 940, the ECU 50 sets the determined target EGR opening degree Tegr to the final target EGR opening degree TEGR.

  In step 950, the ECU 50 controls the EGR valve 53 to the final target EGR opening degree TEGR, and returns the process to step 900.

  On the other hand, in step 960 after proceeding from step 920, the ECU 50 determines whether or not the coolant temperature THW is higher than a predetermined value TH2 (TH2 <TH1). Here, for example, “50 ° C.” can be applied as the predetermined value TH2. The ECU 50 proceeds to step 970 when the determination result is affirmative, and proceeds to step 1000 when the determination result is negative.

  In step 970, the ECU 50 determines whether or not the on-off valve 72 is abnormally closed. The ECU 50 can make this determination by referring to the abnormality determination in the routine shown in FIG. The ECU 50 proceeds to step 980 when the determination result is affirmative, and proceeds to step 940 when the determination result is negative.

  In step 980, the process proceeds from step 970 or step 930, and in step 980, the ECU 50 obtains the corrected target EGR opening degree KTegr. That is, the ECU 50 can obtain the corrected target EGR opening degree KTegr by multiplying the target EGR opening degree Tegr by the low-temperature air correction value Kcol (<1.0). According to this calculation, the post-correction target EGR opening degree KTegr is corrected to decrease the target EGR opening degree Tegr.

  Next, in step 990, the ECU 50 sets the corrected target EGR opening degree KTegr as the final target EGR opening degree TEGR, and the process proceeds to step 950.

  On the other hand, in step 1000, the ECU 50 sets the final target EGR opening degree TEGR to “0”, and the process proceeds to step 950.

  In the above configuration, the water temperature sensor 43 corresponds to an example of a warm-up state detection unit of the present invention for detecting the warm-up state of the intake passage 4. According to the above control, the ECU 50 allows the flow path switching valve 64 to flow in the state where the low-temperature air flows to the downstream side of the intake passage 4, that is, in the state where the valve body 65 is disposed at the low-temperature air position. When the switching valve 64 is diagnosed as having a stuck failure and it is determined that the intake passage 4 has not been warmed up based on the detected coolant temperature THW, the target EGR opening Tegr of the EGR valve 53 is decreased. It is to be corrected. Further, when the ECU 50 diagnoses that the opening / closing valve 72 is in a closed state, the ECU 50 corrects the target EGR opening degree Tegr of the EGR valve 53 by decreasing the amount.

  According to the engine system of this embodiment described above, the following functions and effects can be obtained in addition to the functions and effects of the second embodiment. That is, when there is a change in the intake air temperature THA detected before and after the flow path switching valve 64 is switched, the flow path switching valve 64 is operating normally and switching between the high temperature air and the low temperature air has been performed normally. become. Further, when the detected intake air temperature THA is not changed, the flow path switching valve 64 does not operate normally, and switching between the high temperature air and the low temperature air is not performed normally. The ECU 50 diagnoses a failure of the flow path switching valve 64 based on a change in the intake air temperature THA detected by the intake air temperature sensor 47 before and after the flow path switching valve 64 is controlled to be switched. As described above, the failure of the flow path switching valve 64 can be detected relatively easily by using the intake air temperature sensor 47.

  According to this embodiment, the driver can quickly know that a failure has occurred in the flow path switching valve 64 from the detection result of the failure related to the flow path switching valve 64 described above. For this reason, the driver can cope with the failure of the flow path switching valve 64 at an early stage, and can prevent the occurrence of a secondary failure in the engine 1. For example, it is assumed that the valve body 65 of the flow path switching valve 64 is stuck in a state where the valve element 65 is disposed at the high temperature air position. In this case, since the high-temperature air continues to flow into the engine 1 even after the warm-up of the intake passage 4 is completed, in the combustion chamber 15, the air density is lowered, the fuel combustibility is deteriorated, knocking deterioration, torque reduction, and There is a risk of causing a secondary failure that fuel consumption deteriorates. On the other hand, a case is assumed in which the valve element 65 of the flow path switching valve 64 is stuck in a state where the valve element 65 is disposed at the low temperature air position. In this case, there is a possibility of causing secondary failure such as the generation of condensed water in the intake passage 4 or the throttle valve 9 being fixed due to the freezing of the condensed water. In this embodiment, the failure of the flow path switching valve 64 as described above can be dealt with early, and the occurrence of the secondary failure as described above can be prevented.

  In this embodiment, when there is a change in the intake air amount Ga and the intake pressure PM detected before and after the opening and closing valve 72 is opened and closed, the opening and closing valve 72 has operated normally. On the other hand, if there is no change in the intake air amount Ga or the intake pressure PM detected before and after the opening / closing valve 72 is opened / closed, the opening / closing valve 72 did not operate normally. The ECU 50 detects the change in the intake air amount Ga detected by the air flow meter 45 and the intake pressure sensor 48 before and after the opening / closing valve 72 is controlled to open and close when the opening degree of the electronic throttle device 7 is a predetermined condition. A failure of the on-off valve 72 is diagnosed based on a change in the intake pressure PM. Thus, the failure of the on-off valve 72 can be detected relatively easily by using the air flow meter 45 and the intake pressure sensor 48.

  According to this embodiment, the driver can quickly know that a failure has occurred in the on-off valve 72 from the detection result of the on-off valve 72 failure. For this reason, the driver can cope with the failure of the on-off valve 72 at an early stage, and can prevent the occurrence of a secondary failure in the engine 1. For example, a case is assumed where the on-off valve 72 is in a failure state with the valve open. In this case, even after the warm-up of the EGR distribution pipe 57 is completed, the high-temperature air continues to flow to the engine 1 via the branch flow path 71, the EGR distribution pipe 57, and the like. Therefore, the amount of air supplied to the engine 1 increases by the amount of the high-temperature air, and in the combustion chamber 15, there is a risk of causing a secondary failure such as deterioration of the air-fuel ratio and deterioration of fuel combustibility. is there. On the other hand, it is assumed that the fixing failure occurs while the on-off valve 72 is closed. In this case, the high-temperature air cannot be diverted to the EGR distribution pipe 57 via the diversion passage 71, and the EGR distribution pipe 57 cannot be warmed up with the high-temperature air. There is a risk of causing a secondary failure such as occurrence of a fault. In this embodiment, it becomes possible to cope with the failure of the on-off valve 72 as described above at an early stage, and the occurrence of the secondary failure as described above can be prevented.

  In this embodiment, the ECU 50 diagnoses that the flow path switching valve 64 has failed while the valve element 65 of the flow path switching valve 64 is located at the low temperature air position, and sets the detected coolant temperature THW to the detected coolant temperature THW. Based on this, when it is determined that the warm-up of the intake passage 4 has not been completed, the target EGR opening degree Tegr of the EGR valve 53 is corrected to decrease. Therefore, even when low-temperature air flows to the downstream side of the intake passage 4 when it is cold, the flow rate of EGR gas to the intake passage 4 is suppressed to be low, and early execution of EGR is suppressed. For this reason, even if the flow path switching valve 64 breaks down in a state in which the low-temperature air flows to the intake passage 4 during the cold state, the generation of condensed water due to EGR gas in the intake passage 4 can be suppressed.

  In this embodiment, the ECU 50 corrects the target EGR opening degree Tegr of the EGR valve 53 by decreasing the amount when it is diagnosed that the on-off valve 72 is in a closed state. Therefore, when the high-temperature air is not diverted to the EGR passage 52 downstream from the EGR valve 53 in the cold state, the flow rate of the EGR gas to the EGR passage 52 in that portion is suppressed to a low level. For this reason, even if the on-off valve 72 is in a closed state when it is cold, the generation of condensed water due to EGR gas can be suppressed in the EGR passage 52 downstream from the EGR valve 53.

<Fourth embodiment>
Next, a fourth embodiment that embodies the engine system of the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the above embodiments in terms of the configuration of the diversion adjusting means of the present invention and the contents of EGR control. FIG. 10 is a schematic configuration diagram showing the engine system of this embodiment. In this embodiment, instead of the on-off valve 72 or the control valve 74 in FIG. 1, an orifice 76 that restricts the flow rate of high-temperature air in the diversion passage 71 is provided in the diversion passage 71. The orifice 76 keeps the shunt passage 71 open at all times, but its flow path area is slightly reduced.

  According to the engine system of this embodiment described above, the following operational effects can be obtained from the difference in configuration from the above embodiments. That is, in this embodiment, a small amount of hot air is always diverted to the EGR passage 52 downstream of the EGR valve 53 via the diversion passage 71 by the orifice 76 having a relatively simple configuration. For this reason, the EGR passage 52 downstream from the EGR valve 53 can be warmed up at a relatively low cost, and the generation of condensed water due to EGR gas at that portion can be suppressed.

<Fifth Embodiment>
Next, a fifth embodiment of the engine system according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the fourth embodiment in terms of an additional configuration of the diversion passage 71 of the present invention. In the fourth embodiment, a relatively simple orifice 76 is provided in the diversion passage 71 so that the EGR passage 52 downstream from the EGR valve 53 can be warmed up. However, the amount of high-temperature air that can flow through the diversion passage 71 via the orifice 76 is generally smaller than the amount of air when the engine 1 is idling (idle air amount). With this high-temperature air amount, it takes time to warm up the EGR distribution pipe 57 in practice. On the other hand, even if the passage diameter of the orifice 76 is enlarged and the amount of air that can be passed through is increased, the idling speed of the engine 1 is inadvertently increased. Therefore, in this embodiment, when the engine 1 is idling, even if the amount of high-temperature air that can flow through the orifice 76 is small, normal operation other than idling operation of the engine 1 (during steady operation and acceleration operation). ) Is configured to increase the amount of high-temperature air supplied to the EGR distribution pipe 57.

  FIG. 11 and FIG. 12 are schematic configuration diagrams showing the engine system of this embodiment. FIG. 11 shows a state where the throttle valve 9 is closed, and FIG. 12 shows a state where the throttle valve 9 is opened to some extent. In this embodiment, in addition to the configuration of FIG. 10, a bypass passage 78 is provided that bypasses between the intake passage 4 in the vicinity of the throttle valve 9 of the electronic throttle device 7 and the diversion passage 71 downstream of the orifice 76. FIG. 13 is an enlarged cross-sectional view of the vicinity of the throttle valve 9 of FIG. FIG. 14 is an enlarged sectional view of the vicinity of the throttle valve 9 of FIG. As shown in FIGS. 11 to 14, the bypass passage 78 includes a bypass inlet 78a and a bypass outlet 78b. As shown in FIGS. 11 and 13, the bypass inlet 78a is positioned downstream of the throttle valve 9 when the throttle valve 9 is closed. As shown in FIGS. Is disposed in the intake passage 4 (the casing of the electronic throttle device 7) so as to be located upstream of the throttle valve 9 when opened. FIG. 15 is a sectional view showing the shapes of the diversion inlet 71a and the bypass inlet 78a in the intake passage 4 (the casing of the electronic throttle device 7). In this embodiment, the diversion inlet 71 a has a circular hole, and the bypass inlet 78 a has a long hole along the outer periphery of the throttle valve 9. Further, as shown in FIGS. 11 and 12, the bypass outlet 78 b is disposed in the diversion passage 71 downstream from the orifice 76.

  According to the engine system of this embodiment described above, the following operational effects can be obtained unlike the fourth embodiment. That is, in this embodiment, when the throttle valve 9 is closed, the flow of high-temperature air to the bypass inlet 78a is blocked, and the high-temperature air does not flow to the EGR passage 52 downstream from the EGR valve 53 via the bypass passage 78. . On the other hand, when the throttle valve 9 is opened, high-temperature air flows into the bypass inlet 78 a, and high-temperature air flows through the bypass passage 78 to the EGR passage 52 downstream from the EGR valve 53. Further, the flow rate of the high-temperature air is adjusted according to the opening degree of the throttle valve 9. Therefore, during idling or deceleration operation of the engine 1 where the throttle valve 9 is closed, a small amount of high-temperature air can be diverted to the EGR passage 52 downstream from the EGR valve 53 via the diversion passage 71. . Further, during normal operation of the engine 1 where the throttle valve 9 is opened, high-temperature air can be further diverted to the EGR passage 52 downstream of the EGR valve 53 via the bypass passage 78, and the EGR downstream of the EGR valve 53 by that amount. The amount of high-temperature air that can be diverted to the passage 52 can be increased. In addition, since the throttle valve 9 is used, the inflow of high-temperature air into the bypass passage 78 can be adjusted without separately providing a dedicated adjusting means.

  In this embodiment, part of the high-temperature air flowing through the intake passage 4 in the vicinity of the electronic throttle device 7 (throttle valve 9) is diverted to the diversion passage 71 downstream of the orifice 76 via the bypass passage 78. Accordingly, the amount of hot air that is diverted to the EGR passage 52 downstream of the EGR valve 53 is increased by the amount of hot air that flows through the bypass passage 78. For this reason, the EGR passage 52 downstream of the EGR valve 53 can be warmed up in a shorter time than the configuration of the fourth embodiment having no bypass passage 78.

  In this embodiment, the bypass inlet 78 a of the bypass passage 78 forms a long hole along the outer periphery of the throttle valve 9. For this reason, when the throttle valve 9 is opened, high temperature air can be easily flown into the bypass passage 78 from the bypass inlet 78a.

<Sixth Embodiment>
Next, a sixth embodiment of the engine system according to the present invention will be described in detail with reference to the drawings.

  This embodiment is different from the fifth embodiment in terms of an additional configuration of the diversion passage 71 of the present invention. In the fifth embodiment, since air flows into the EGR distribution pipe 57 via the bypass passage 78 during normal operation of the engine 1, the internal pressure of the EGR distribution pipe 57 increases. As a result, when the engine 1 is operating at a high load, the differential pressure across the EGR valve 53 acts in a direction that decreases, and the EGR gas flow rate passing through the EGR valve 53 may decrease. Therefore, in this embodiment, in the configuration of the fifth embodiment, the diversion passage 71 is appropriately blocked so that air does not flow into the EGR distribution pipe 57.

  FIG. 16 is a schematic configuration diagram showing the engine system of this embodiment. FIG. 17 is an enlarged cross-sectional view of the vicinity of the check valve 80 of FIG. In this embodiment, as shown in FIGS. 16 and 17, a check valve 80 is provided in the diversion passage 71 downstream from the bypass outlet 78b. The check valve 80 is configured to open when a differential pressure before and after the check valve reaches a predetermined value or more to flow hot air downstream and to prevent the reverse flow. That is, as shown in FIG. 17, the check valve 80 includes a casing 80a, a valve seat 80b formed on the upstream side of the casing 80a, a spherical valve body 80c provided to be seated on the valve seat 80b, A spring 80d for urging the valve body 80c in the valve closing direction to seat the valve body 80c on the valve seat 80b. In this configuration, the check valve 80 moves in the downstream direction against the biasing force of the spring 80d when the differential pressure between the upstream pressure and the downstream pressure exceeds a predetermined value. To open.

  According to the engine system of this embodiment described above, the following functions and effects can be obtained in addition to the functions and effects of the fifth embodiment. That is, in this embodiment, when the engine 1 is operating at a high load, the intake negative pressure acting on the EGR passage 52 from the EGR outlet 52b is reduced, the check valve 80 is closed, and the branch passage 71 is shut off. On the other hand, during low load operation of the engine 1, the intake negative pressure acting on the EGR passage 52 from the EGR outlet 52 b increases, the front-rear differential pressure of the check valve 80 exceeds a predetermined value, and the check valve 80 opens. The flow path 71 is opened. Accordingly, when the valve element 65 of the flow path switching valve 64 is switched to the high temperature air position, the high temperature air is allowed to be diverted from the diversion passage 71 to the EGR passage 52 downstream of the EGR valve 53. Here, if there is no check valve 80 in the diversion passage 71, in the diversion passage 71 provided with the orifice 76, a small amount of air that bypasses the electronic throttle device 7 always flows when the engine 1 is operated. . The air always flows to the EGR passage 52 downstream from the EGR valve 53. For this reason, the internal pressure increases in the EGR passage 52 downstream from the EGR valve 53. When the throttle valve 9 is largely opened, that is, when the engine 1 is operating at a high load, air also flows into the bypass passage 78, the differential pressure across the EGR valve 53 decreases, and the EGR gas flow rate through the EGR valve 53 decreases. . In the above configuration, the check valve 80 is closed until the differential pressure across the check valve 80 becomes equal to or greater than a predetermined value, and the flow of hot air to the EGR passage 52 downstream from the EGR valve 53 is blocked. For this reason, a decrease in the differential pressure across the EGR valve 53 can be suppressed, and a decrease in the EGR gas flow rate in the EGR passage 52 can be suppressed during EGR execution.

  In addition, this invention is not limited to each said embodiment, A part of structure can also be changed suitably and implemented in the range which does not deviate from the meaning of invention.

  (1) In each of the above embodiments, the EGR distribution pipe 57 is formed in a tournament table type, but as shown in FIG. 18, the EGR distribution pipe is formed by branching four branch pipes 59b from one main pipe 59a in parallel. The pipe 59 can also be provided at the downstream end of the EGR passage 52. FIG. 18 is a schematic diagram showing an EGR distribution pipe 59 according to FIG.

  (2) In each of the above embodiments, the EGR distribution pipe 57 is provided in the EGR passage 52 downstream from the EGR valve 53. However, the EGR distribution pipe may be omitted. When the EGR distribution pipe is omitted, the EGR outlet of the EGR passage is communicated with the surge tank of the intake manifold.

  The present invention can be used in an engine system configured to recirculate a part of exhaust discharged from an engine as an exhaust gas recirculation gas to an engine through an intake passage and to introduce heated air into the intake passage. it can.

1 Engine 2 Cylinder 4 Intake passage 5 Exhaust passage 6 Air cleaner 7 Electronic throttle device (intake air amount adjustment valve)
8 Intake manifold 8a Surge tank 8b Branch passage 9 Throttle valve 15 Combustion chamber 27 Accelerator pedal (accelerator operating means)
42 Accelerator sensor (accelerator detection means)
43 Water temperature sensor (warm-up state detection means)
47 Intake air temperature sensor (intake air temperature detection stage)
48 Intake pressure sensor (Intake pressure detection means)
50 ECU (control means, flow path switching valve failure diagnosis means, on-off valve failure diagnosis means)
52 EGR passage (exhaust gas recirculation passage)
52a EGR inlet (exhaust gas recirculation inlet)
52b EGR outlet (exhaust gas recirculation outlet)
53 EGR valve (exhaust gas recirculation valve)
57 EGR distribution pipe (exhaust gas recirculation pipe)
59 EGR distribution pipe (exhaust gas recirculation distribution pipe)
62 shroud 63 high temperature air passage 64 flow path switching valve 71 branch flow path 71a branch flow inlet 71b branch flow outlet 72 on-off valve (flow distribution adjusting means)
74 Control valve (Diversion control means)
76 Orifice (Diversion control means)
78 Bypass passage 78a Bypass inlet 78b Bypass outlet 80 Check valve ACC Accelerator opening THW Cooling water temperature Ga Intake amount THA Intake temperature PM Intake pressure Tegr Target EGR opening

Claims (15)

An intake passage for introducing intake air into the engine;
The intake passage includes an intake inlet, and introduces outside air as cold air from the intake inlet;
An intake air amount adjustment valve for adjusting the intake air amount in the intake passage;
An exhaust passage for leading exhaust from the engine;
A hot air passage connected to the intake passage for introducing hot air heated by a heating means into the intake passage;
A flow path is provided at a connection portion between the intake passage and the high temperature air passage to selectively flow the high temperature air from the high temperature air passage and the low temperature air from the intake inlet to the downstream side of the intake passage. A flow path switching valve for switching,
An exhaust gas recirculation passage for flowing a part of the exhaust gas led out from the engine to the exhaust gas passage as an exhaust gas recirculation gas to the intake passage and recirculating to the engine;
The exhaust gas recirculation passage includes an exhaust gas recirculation inlet and an exhaust gas recirculation outlet; the exhaust gas recirculation inlet communicates with the exhaust passage; the exhaust gas recirculation outlet communicates with the intake passage downstream of the intake air amount adjustment valve;
An exhaust gas recirculation valve for adjusting the flow rate of the exhaust gas recirculation gas in the exhaust gas recirculation passage;
In an engine system comprising at least the flow path switching valve and a control means for controlling the exhaust gas recirculation valve,
A diversion passage for diverting a part of the high-temperature air introduced from the high-temperature air passage to the intake passage to the exhaust gas recirculation passage;
The diversion passage includes a diversion inlet and a diversion outlet, the diversion inlet is in communication with the intake passage downstream of the flow path switching valve and upstream of the intake air amount adjustment valve, and the diversion outlet is the exhaust gas recirculation. Communicating with the exhaust gas recirculation passage downstream of the valve;
An engine system comprising: a diversion adjusting means for adjusting a flow rate of the high-temperature air in the diversion passage. The engine is a reciprocating engine having a plurality of cylinders,
The intake passage is branched into a plurality of branch passages immediately before the engine in order to distribute the intake air to the cylinders,
2. The engine system according to claim 1, wherein the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve includes an exhaust gas recirculation distribution pipe for distributing the exhaust gas recirculation gas flowing through the passage to the branch passages. .   2. The engine system according to claim 1, wherein the diversion outlet of the diversion passage communicates with the exhaust recirculation passage in the vicinity of the exhaust recirculation valve.   The engine system according to claim 1, wherein the branch flow adjusting means is an orifice that restricts a flow rate of the high-temperature air.   5. The engine system according to claim 4, further comprising a bypass passage that bypasses between the intake passage in the vicinity of the intake air amount adjustment valve and the diversion passage downstream of the orifice. The intake air amount adjusting valve includes a butterfly throttle valve,
The bypass passage includes a bypass inlet and a bypass outlet, and the bypass inlet is positioned downstream of the throttle valve when the throttle valve is closed, and upstream of the throttle valve when the throttle valve is opened. The engine system according to claim 5, wherein the engine system is arranged in the intake passage.   The bypass outlet is disposed in the branch passage, and a check valve is provided in the branch passage downstream from the bypass outlet, and the check valve opens when a differential pressure across the front and rear becomes a predetermined value or more. The engine system according to claim 6, wherein the high-temperature air is caused to flow downstream. The diversion adjusting means is an on-off valve that selectively opens and closes the diversion passage,
The control means controls the opening of the on-off valve when switching the flow path switching valve in order to flow the high temperature air from the high temperature air passage to the downstream side of the intake passage. The engine system according to claim 1. An accelerator operating means operated by a driver to request acceleration of the engine;
An accelerator detection means for detecting an operation amount of the accelerator operation means,
The diversion adjusting means is a control valve that opens and closes the diversion passage so that the opening is variable.
The control means controls the control valve according to a detection value of the accelerator detection means when the flow path switching valve is controlled to flow the high temperature air from the high temperature air passage to the downstream side of the intake passage. The engine system according to claim 1, wherein the degree of opening is controlled.   The control means is configured to divert the high-temperature air to the exhaust gas recirculation passage downstream of the exhaust gas recirculation valve through the diversion passage and permit the opening of the exhaust gas recirculation valve. The engine system according to claim 8 or 9, wherein the target opening of the recirculation valve is corrected to increase.   When the control means diverts the high temperature air to the exhaust gas recirculation passage downstream from the exhaust gas recirculation valve via the diversion passage, the control means sets the target of the intake air amount adjustment valve according to the detected value of the accelerator detection means. The engine system according to claim 9, wherein the opening degree is corrected to decrease. A flow path switching valve failure diagnosing means for diagnosing that the flow path switching valve has failed in a state where the low-temperature air from the intake inlet flows to the downstream side of the intake passage;
Further comprising a warm-up state detection means for detecting a warm-up state of the intake passage,
In the control means, the flow path switching valve failure diagnosis means diagnoses that the flow path switching valve is in failure, and the warm-up of the intake passage is incomplete based on the detection result by the warm-up state detection means. The engine system according to claim 8, wherein when it is determined that there is a target, the target opening of the exhaust gas recirculation valve is corrected to decrease. An intake air temperature detecting means for detecting an intake air temperature in the intake passage downstream from the flow path switching valve;
The flow path switching valve failure diagnosis means diagnoses the failure of the flow path switching valve based on the intake air temperature detected by the intake air temperature detection means before and after the flow path switching valve is controlled to be switched. The engine system according to claim 12. An on-off valve failure diagnosing means for diagnosing that the on-off valve has failed in a closed state;
9. The engine system according to claim 8, wherein the control means corrects the target opening of the exhaust gas recirculation valve by decreasing when the on-off valve failure diagnosing means diagnoses that the on-off valve is in failure. . An intake air amount detecting means for detecting an intake air amount flowing through the intake passage;
An intake pressure detection means for detecting an intake pressure in the intake passage downstream of the intake air amount adjustment valve;
The on-off valve failure diagnosis means is configured to detect the intake air amount detected by the intake air amount detection means and the intake air before and after the on-off valve is controlled to open and close when the opening amount of the intake air amount adjustment valve is a predetermined condition. The engine system according to claim 14, wherein a failure of the on-off valve is diagnosed on the basis of the intake pressure detected by a pressure detection means.

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