JP2020122473A - Engine device and method of controlling engine device - Google Patents

Abstract

To prevent the inside of an engine and an intake system from corroding by effectively deterring condensate water from being generated.SOLUTION: An engine device comprises: an engine 10 mounted on a vehicle 1; an exhaust recirculation device 50 which recirculates at least part of exhaust of the engine 10 to an intake system; a control unit 120 which executes, based upon an operation state of the engine 10, exhaust recirculation control to control a recirculation rate of exhaust by the exhaust recirculation device 50; cumulative travel quantity units 93, 110 which acquire a cumulative travel quantity of the vehicle 1; and limitation units 130, 170 which inhibit the exhaust recirculation control from being executed, or reduce the recirculation rate of the exhaust by the exhaust recirculation control until the cumulative travel quantity acquired from the start of an initial travel of the vehicle 1 reaches a predetermined threshold travel quantity.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to an engine device and a method for controlling the engine device.

As an example of this type of engine device, a device provided with an exhaust gas recirculation system (hereinafter referred to as an EGR device) that recirculates at least a part of exhaust gas to an intake system to reduce NOx contained in the exhaust gas It is known (see, for example, Patent Documents 1 and 2).

JP, 2018-105189, A JP2012-188944A

In an engine equipped with an EGR device, for example, if the vehicle frequently repeats short-distance movements after production until delivery, and the engine is repeatedly started/stopped accordingly, the cooling water temperature changes to a low temperature state during that period. Will be done. Therefore, the condensed water generated from the EGR gas or the water vapor contained in the EGR gas may remain in the cylinder. Since such condensed water contains corrosive substances (for example, sulfuric acid, nitric acid, etc.), if the condensed water is left in the cylinder or in the intake system, the engine such as intake/exhaust valves and injectors It may cause corrosion or damage to internal parts and intake system parts.

The technique of the present disclosure aims to prevent corrosion of the inside of the engine and the intake system by effectively suppressing the generation of condensed water.

The device of the present disclosure includes an engine mounted on a vehicle, an exhaust gas recirculation device that recirculates at least a part of the exhaust gas of the engine to an intake system, an operation state acquisition unit that acquires an operation state of the engine, and an acquisition device. Control means for executing exhaust gas recirculation control for controlling the exhaust gas recirculation rate or recirculation amount by the exhaust gas recirculation device based on the operating state, and cumulative running amount for acquiring the cumulative running amount of the vehicle Between the acquisition means and the start of the initial running of the vehicle until the accumulated travel amount acquired reaches a predetermined threshold travel amount, either prohibiting the execution of the exhaust gas recirculation control or the exhaust gas recirculation. And a limiting means for reducing the exhaust gas recirculation rate or the recirculation amount by control.

Further, if the cooling water temperature of the engine exceeds a predetermined threshold water temperature and the generation of condensed water does not occur even before the cumulative travel amount reaches the threshold travel amount, the limiting means is the control means. It is preferable to permit the execution of the exhaust gas recirculation control by.

Further, when the exhaust gas recirculation rate or the recirculation amount by the exhaust gas recirculation control is reduced, the limiting means greatly reduces the recirculation rate or the recirculation amount as the cooling water temperature of the engine becomes lower. It is preferable.

Further, the limiting means controls the exhaust gas recirculation control by the control means while the vehicle speed of the vehicle exceeds a predetermined threshold vehicle speed even before the cumulative travel amount reaches the threshold travel amount. It is preferable to allow execution.

The method of the present disclosure includes an engine mounted on a vehicle, an exhaust gas recirculation device that recirculates at least a part of exhaust gas of the engine to an intake system, and an exhaust gas recirculation device based on an operating state of the engine. A control method for executing an exhaust gas recirculation control for controlling an exhaust gas recirculation rate or an exhaust gas recirculation amount, the method comprising: Until the accumulated travel amount reaches a predetermined threshold travel amount, the execution of the exhaust gas recirculation control is prohibited, or the exhaust gas recirculation rate or the recirculation amount by the exhaust gas recirculation control is set. It is characterized by reducing.

According to the technique of the present disclosure, it is possible to prevent corrosion of the inside of the engine and the intake system by effectively suppressing the generation of condensed water.

1 is a schematic overall configuration diagram showing an engine device mounted on a vehicle according to the present embodiment. FIG. 3 is a schematic functional block diagram showing an electronic control unit according to the first embodiment and related peripheral configurations. It is a flow chart figure explaining EGR prohibition processing concerning a first embodiment. It is a schematic functional block diagram which shows the electronic control unit which concerns on 2nd embodiment, and a related peripheral structure. It is a flowchart figure explaining the EGR reduction process which concerns on 2nd embodiment. It is a flow chart figure explaining EGR prohibition processing concerning a third embodiment. It is a flowchart figure explaining the EGR reduction process which concerns on 4th embodiment. It is a flow chart figure explaining EGR prohibition processing concerning other embodiments. It is a flowchart figure explaining the EGR reduction process which concerns on other embodiment.

Hereinafter, an engine device according to the present embodiment and a method for controlling the engine device will be described with reference to the accompanying drawings. The same parts are designated by the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[overall structure]
FIG. 1 is a schematic overall configuration diagram showing an engine device mounted on a vehicle 1 according to the present embodiment.

The engine 10 mainly has an engine body including a cylinder head 11 and a cylinder block 16.

The cylinder block 16 is provided with a cylinder C that accommodates the piston P in a reciprocating manner. A crankshaft CS is connected to the piston P via a connecting rod CR, a crank arm CA, etc., and the reciprocating motion of the piston P is converted into rotational motion and transmitted to the crankshaft CS. For the sake of illustration, only one cylinder is shown in FIG. 1 among the plurality of cylinders of the engine 10, and the other cylinders are not shown. The engine 10 may be either a plurality of cylinders or a single cylinder.

The cylinder head 11 is provided with an intake port 11A for introducing intake air into the cylinder C and an exhaust port 11B for exhausting exhaust gas from the cylinder C. Further, the cylinder head 11 is provided with an intake valve 12 and an exhaust valve 14 which are opened and closed by a valve mechanism (not shown). Further, the cylinder head 11 is provided with an injector 15 for directly injecting fuel into the cylinder C. The fuel injection amount and injection timing of the injector 15 are controlled according to an instruction signal input from an electronic control unit (ECU) 100. The engine 10 is not limited to the direct injection type engine, and may be a premix type engine.

An intake manifold 20 communicating with the intake port 11A is provided on the intake side of the cylinder head 11. An intake passage 21 for introducing intake air is connected to the intake manifold 20. In the intake passage 21, an air cleaner 22, a compressor 32 of the supercharger 30, an intercooler 23, and the like are provided in order from the intake upstream side.

An exhaust manifold 25 that communicates with the exhaust port 11B is provided on the side of the cylinder head 11 on the exhaust side. An exhaust passage 26 is connected to the exhaust manifold 25 to guide the exhaust to the atmosphere. In the exhaust passage 26, a turbine 31 of the supercharger 30, an exhaust purification device (not shown), and the like are provided in order from the exhaust upstream side.

The supercharger 30 includes a turbine 31 that is driven by exhaust gas, and a compressor 32 that is connected to the turbine 31 via a rotating shaft and pressure-feeds intake air. The supercharger 30 is not limited to the conventional type shown in the figure, and may be a variable capacity type having variable blades.

The EGR device 50 includes an EGR passage 51 that recirculates at least a part of the exhaust gas flowing through the exhaust passage 26 to the intake passage 21 as EGR gas, a water-cooled EGR cooler 52 that cools the EGR gas, and an EGR passage 51 that is opened and closed. And a possible EGR valve 53. The EGR valve 53 is preferably provided in the EGR passage 51 on the downstream side of the EGR cooler 52. The opening degree of the EGR valve 53 is controlled according to a command from the ECU 100. The EGR device 50 is not limited to the high pressure EGR device in the illustrated example, and may be a low pressure EGR device that recirculates the EGR gas to the intake passage 21 on the upstream side of the compressor 32.

The cooling water circulation device 60 is a radiator 61 that cools cooling water by heat exchange with the outside air, a water jacket 62 formed in the cylinder block 16, and an upstream portion that connects the outlet portion of the water jacket 62 and the inlet portion of the radiator 61. A pipe 63, a downstream pipe 64 that connects the outlet of the radiator 61 and an inlet of the water jacket 62, a bypass pipe 65 that connects the upstream pipe 63 and the downstream pipe 64 to bypass the radiator 61, and an upstream pipe 63. The thermostat 66 is provided at a branch portion between the bypass pipe 65 and the bypass pipe 65, and a pressure pump 67 that pressure-feeds the cooling water. A water-cooled EGR cooler 52 is provided at a predetermined portion of the downstream pipe 64.

A water temperature sensor 90 that acquires the temperature of cooling water (hereinafter, cooling water temperature T) flowing from the water jacket 62 into the upstream pipe 63 is provided near the outlet of the water jacket 62 of the upstream pipe 63. The sensor value of the water temperature sensor 90 is transmitted to the ECU 100 electrically connected.

The engine speed sensor 91 acquires the engine speed Ne from the crankshaft CS. The fuel injection amount acquisition unit 92 acquires an injection instruction value for the injector 15 calculated from the accelerator opening degree according to the depression amount of an accelerator pedal (not shown). The vehicle speed sensor 93 acquires the vehicle speed V from a shaft (for example, a propeller shaft) that transmits the power of the engine 10 to drive wheels (not shown) of the vehicle 1. The sensor values of these sensors 91 to 93 are transmitted to the ECU 100 electrically connected.

The engine speed sensor 91 and the fuel injection amount acquisition unit 92 are an example of the operating state acquisition unit of the present disclosure, and the vehicle speed sensor 93 constitutes a part of the cumulative travel amount acquisition unit of the present disclosure. The operating state acquisition unit is not limited to the engine speed sensor 91 and the fuel injection amount acquisition unit 92, and may include other sensors such as an intake flow rate sensor and a boost pressure sensor. Further, the accumulated travel amount acquisition means may be a wheel speed sensor or the like (not shown).

[First embodiment]
FIG. 2 is a schematic functional block diagram showing the ECU 100 according to the first embodiment and related peripheral configurations.

The ECU 100 performs various controls of the engine 10 and the like, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, an output port, and the like. Further, the ECU 100 includes the cumulative traveling distance calculation unit 110 (a part of the cumulative traveling amount acquisition unit), the EGR control unit 120 (control unit of the present disclosure), and the EGR prohibition processing unit 130 (an example of the limiting unit of the present disclosure). And an EGR prohibition canceling unit 140 (an example of limiting means of the present disclosure) as some functional elements. In the present embodiment, each of these functional elements will be described as being included in the ECU 100, which is an integral piece of hardware, but any of these may be provided in separate pieces of hardware.

The cumulative traveling distance calculation unit 110 sequentially accumulates the traveling distance obtained by dividing the sensor value of the vehicle speed sensor 93 by time from the initial traveling start of the vehicle 1 (for example, factory shipment after vehicle production), thereby The cumulative travel distance D from the start of the initial travel of 1 is calculated. The cumulative travel distance D calculated by the cumulative travel distance calculation unit 110 is transmitted to the EGR prohibition processing unit 130 and the EGR prohibition cancellation unit 140.

The EGR control unit 120 executes the normal EGR control that controls the opening degree of the EGR valve 53 so that the NOx emission amount of the engine 10 reaches a desired target value based on the operating state of the engine 10. Specifically, a memory (not shown) of the ECU 100 stores an engine speed Ne and an EGR map M1 that defines a target EGR rate according to the fuel injection amount. In the normal EGR control, the target EGR rate is set by referring to the EGR map M1 based on the sensor values of the engine rotation sensor 91 and the fuel injection amount acquisition unit 92, and an instruction signal corresponding to the target EGR rate is set. Is transmitted to an actuator (not shown) of the EGR valve 53.

The EGR prohibition processing unit 130 continues the normal-time EGR control by the EGR control unit 120 based on the EGR map M1 until the cumulative traveling distance D transmitted from the cumulative traveling distance computing unit 110 reaches a predetermined threshold distance _{D_th.} Is prohibited, in other words, the EGR valve 53 is forcibly maintained in the fully closed state (hereinafter, the prohibition process is also referred to as an EGR prohibition mode). Here, the threshold distance _{D_th} may be set on the basis of, for example, the distance (for example, about 20 km) from the production of the vehicle 1 to the delivery of the vehicle 1 in which the engine 10 frequently starts and stops.

In this way, the vehicle 1 is repeatedly moved a short distance frequently, and during the period until the vehicle is delivered in which the temperature of the engine 10 is unlikely to rise, by prohibiting the execution of the normal EGR control, the condensation generated by cooling the EGR gas is performed. It becomes possible to effectively suppress the generation of water. The EGR prohibition mode is automatically disabled when the cumulative traveling distance D of the vehicle 1 reaches a predetermined threshold distance _{D_th} , that is, the normal EGR control by the EGR control unit 120 is switched to valid. ..

Note that the EGR prohibition mode may be enabled/disabled selectively by a service tool 95 (externally connected device) or the like that can be input to the ECU 100. With this configuration, for example, even when the vehicle 1 is not operated for a long period of time due to maintenance or the like, it is possible to appropriately enable the EGR prohibition mode.

Further, while the EGR prohibition mode is valid, a display indicating that the EGR prohibition mode is valid is displayed on a display panel provided in a driver's cab (not shown) of the vehicle 1 in order to provide the driver with such information. The lamp 200 may be turned on. The lamp 200 may be a dedicated lamp, or may be used as a lamp for another mode (for example, a lamp indicating an engine failure). In the case of dual use, in order to distinguish it from other modes, the dual use lamp may be blinked while the EGR prohibition mode is valid.

The EGR prohibition canceling unit 140 determines that the cooling water temperature T transmitted from the water temperature sensor 90 is _equal to the predetermined threshold water temperature T even before the cumulative traveling distance D transmitted from the cumulative traveling distance calculating unit 110 reaches the threshold distance _{D_th. While _th} is exceeded, the EGR prohibition mode is released. That is, while the cooling water temperature T exceeds the predetermined threshold water temperature _{T_th} , the normal time EGR control based on the EGR map M1 by the EGR control unit 120 is temporarily switched to valid (permitted). .. Here, the threshold water temperature _{T_th} may be set based on a temperature at which condensed water is less _likely to be generated by cooling the EGR gas (for example, about 60 degrees lower than the warm-up temperature). As described above, during a period in which the cooling water temperature T exceeds the predetermined threshold water temperature _{T_th} , the normal-time EGR control is temporarily enabled over the period, so that the deterioration of the exhaust emission performance is effectively suppressed. Become so.

Next, the flow of the EGR prohibition process according to the present embodiment will be described based on FIG. It should be noted that this routine preferably starts at the same time when the initial running of the vehicle 1 is started.

In step S100, the cumulative travel distance D from the start of the initial travel of the vehicle 1 is calculated in real time (or at every predetermined calculation cycle).

In step S110, it is determined whether the cumulative traveling distance D has reached the threshold distance _{D_th} . When the cumulative traveling distance D has not reached the threshold distance _{D_th} (No), the control proceeds to step S120. On the other hand, when the cumulative traveling distance D has reached the threshold distance _{D_th} (Yes), the present control proceeds to step S180, the normal time EGR control is made valid (the EGR prohibition mode is made invalid), and then the process ends.

When the process proceeds from step S110 to step S120, that is, when the cumulative traveling distance D does not reach the threshold distance _{D_th} , it is determined whether the cooling water temperature T exceeds the threshold water temperature _{T_th} . When the cooling water temperature T exceeds the threshold water temperature _{T_th} (Yes), the control proceeds to step S130, the normal time EGR control is validated, and then the process _returns to step S100. That is, even before the cumulative travel distance D reaches the threshold distance _{D_th} , during the period in which the cooling water temperature T exceeds the threshold water temperature _{T_th} , the normal time EGR control is temporarily enabled over the period. ..

On the other hand, in step S120, when the cooling water temperature T does not exceed the threshold water temperature _{T_th} (No), the control proceeds to step S140 and prohibits the execution of the normal EGR control (keeps the EGR valve 53 fully closed). Then, the process returns to step S100. That is, before the cumulative traveling distance D reaches the threshold distance _{D_th} and while the cooling water temperature T is lower than the threshold water temperature _{T_th} , execution of the normal time EGR control is prohibited.

According to the first embodiment described in detail above, the execution of the normal time EGR control is prohibited from the start of the initial travel of the vehicle 1 until the cumulative travel distance D reaches the threshold distance _{D_th} . .. That is, during a period until the vehicle 1 is frequently repeatedly moved for a short distance and the temperature of the engine 10 is unlikely to rise, execution of the EGR control at normal time is prohibited, so that the condensed water generated by cooling the EGR gas is prohibited. It is configured so that it can be effectively suppressed. This makes it possible to prevent the corrosive condensed water from remaining in the cylinder C and the intake system, and effectively prevent the inside of the engine 10 and the intake system from being corroded.

Even before the cumulative travel distance D from the start of the initial travel of the vehicle 1 reaches the threshold distance _{D_th} , the period in which the cooling water temperature T of the engine 10 exceeds the predetermined threshold water temperature _{T_th continues} for the period. The EGR prohibition mode is released by using the EGR control mode to temporarily enable (permit) the execution of the EGR control at the normal time. As a result, even before the cumulative travel distance D reaches the threshold distance _{D_th} , if the cooling water temperature T has reached a temperature at which the generation of condensed water can be suppressed, the normal time EGR control is appropriately performed. As a result, deterioration of exhaust emission performance can be effectively suppressed.

[Second embodiment]
Next, an engine device according to the second embodiment and a method for controlling the engine device will be described with reference to FIGS.

FIG. 4 is a schematic functional block diagram showing the ECU 100 according to the second embodiment and related peripheral configurations.

The ECU 100 according to the second embodiment includes the EGR prohibition processing unit 130 and the EGR prohibition canceling unit 140 of the first embodiment as an EGR reduction correcting unit 170 (an example of a limiting unit of the present disclosure) and an EGR reduction canceling unit 180. They are each replaced. The other functional elements have the same functions as those in the first embodiment, and detailed description thereof will be omitted.

The EGR reduction correction unit 170 corrects the target EGR rate defined in the EGR map M1 to a low EGR rate until the cumulative travel distance D transmitted from the cumulative travel distance calculation unit 110 reaches the threshold distance _{D_th.} The EGR rate reduction correction is executed (hereinafter, the reduction correction is also referred to as an EGR rate reduction mode).

Specifically, the memory of the ECU 100 stores a correction coefficient map M2 that defines a correction coefficient k for reducing and correcting the target EGR rate of the EGR map M1. In the correction coefficient map M2, the correction coefficient k is set such that the target EGR rate is greatly reduced as the cooling water temperature T decreases. In the EGR rate reduction correction, the correction coefficient k is read by referring to the correction coefficient map M2 based on the cooling water temperature T transmitted from the water temperature sensor 90, and the target EGR rate of the EGR map M1 is calculated based on the correction coefficient k. It is executed by reducing correction. The value of the correction coefficient k may be appropriately set according to the specifications of the engine 10 and the EGR device 50.

As described above, during a period until the vehicle 1 is repeatedly repeatedly moved for a short distance and the temperature of the engine 10 is hard to rise, the EGR rate is appropriately reduced and corrected by the EGR control in the normal time to cool the EGR gas. While effectively suppressing the generation of condensed water that is generated, it is possible to effectively suppress deterioration of exhaust emission performance as compared with the case where EGR control is completely prohibited. The EGR rate reduction mode is automatically disabled when the cumulative traveling distance D of the vehicle 1 reaches a predetermined threshold distance _{D_th} , that is, the normal EGR control by the EGR control unit 120 is switched to valid. There is.

The EGR rate reduction mode may be enabled/disabled selectively by a service tool 95 (externally connected device) that can be input to the ECU 100. According to this structure, for example, even when the vehicle 1 is not operated for a long time due to maintenance or the like, it is possible to appropriately enable the EGR rate reduction mode.

In addition, while the EGR rate reduction mode is valid, the EGR rate reduction mode is valid on a display panel provided in a driver's cab (not shown) of the vehicle 1 in order to provide the driver with such information. The lamp 200 for displaying may be turned on. The lamp 200 may be a dedicated lamp or may be used as a lamp for another mode (for example, a lamp indicating an engine failure). In the case of the combined use, the combined lamp may be blinked while the EGR rate reduction mode is effective in order to distinguish it from other modes.

EGR reduces release unit 180, even before the cumulative travel distance D to be transmitted from the accumulated running distance computation unit 110 reaches the threshold distance _{D - th,} cooling water temperature T transmitted from the water temperature sensor 90 is a threshold temperature _{T - th} While exceeding, the EGR rate reduction mode by the EGR reduction correction unit 170 is canceled. That is, during the period when the cooling water temperature T exceeds the predetermined threshold water temperature _{T_th} , the normal time EGR control by the EGR control unit 120 can be temporarily and effectively switched over the period.

Next, a flow of EGR reduction processing according to the present embodiment will be described based on FIG. It should be noted that this routine preferably starts at the same time when the initial running of the vehicle 1 is started.

In step S200, the cumulative travel distance D from the start of the initial travel of the vehicle 1 is calculated in real time (or at every predetermined calculation cycle).

In step S210, it is determined whether the cumulative traveling distance D has reached the threshold distance _{D_th} . When the cumulative traveling distance D has not reached the threshold distance _{D_th} (No), the control proceeds to step S220. On the other hand, when the cumulative traveling distance D has reached the threshold distance _{D_th} (Yes), the control proceeds to step S280, the normal time EGR control is enabled (the EGR rate reduction mode is disabled), and then the process ends.

When the process proceeds from step S210 to step S220, that is, when the cumulative traveling distance D does not reach the threshold distance _{D_th} , it is determined whether the cooling water temperature T exceeds the threshold water temperature _{T_th} . When the cooling water temperature T exceeds the threshold water temperature _{T_th} (Yes), the control proceeds to step S230, the normal time EGR control is validated, and then the process _returns to step S200. That is, even before the cumulative travel distance D reaches the threshold distance _{D_th} , during the period in which the cooling water temperature T exceeds the threshold water temperature _{T_th} , the normal time EGR control is temporarily enabled (permitted) over the period. ).

On the other hand, in step S220, when the cooling water temperature T does not exceed the threshold water temperature _{T_th} (No), the control proceeds to step S240, the reduction correction for reducing the target EGR rate of the EGR map M1 is performed, and then step S200. Returned to the processing of. That is, before the cumulative traveling distance D reaches the threshold distance _{D_th} and while the cooling water temperature T is lower than the threshold water temperature _{T_th} , reduction correction is performed to make the target EGR rate lower than in the normal EGR control. Become so.

According to the second embodiment described in detail above, from the start of the initial traveling of the vehicle 1 until the cumulative traveling distance D reaches the threshold distance _{D_th} , the EGR rate for correcting the target EGR rate in accordance with the cooling water temperature T is reduced. While the reduction mode is enabled, the EGR rate reduction mode is temporarily released during the period when the cooling water temperature T exceeds the predetermined threshold water temperature _{T_th} . This makes it possible to effectively prevent corrosive condensed water from remaining in the cylinder C or in the intake system, and effectively prevent corrosion in the engine 10 or the intake system. Further, even when the cooling water temperature T does not exceed the threshold water temperature _{T_th} , it is possible to effectively prevent a significant deterioration of exhaust emission performance by operating at a low EGR rate without completely prohibiting EGR control. You can

[Third embodiment]
FIG. 6 is a diagram illustrating a flow of EGR prohibition processing according to the third embodiment. In the third embodiment, the determination process of step S120 shown in FIG. 3 of the first embodiment is replaced with step S320 of determining whether or not the vehicle speed V exceeds a predetermined threshold speed _{V_th} . Here, the threshold speed _{V_th} may be set based on, for example, a vehicle speed (for example, about 80 km/h) that can raise the cooling water temperature T to a predetermined high water temperature at which the generation of condensed water is suppressed.

Hereinafter, the flow of the EGR prohibition process according to the third embodiment will be described with reference to FIG.

In step S300, the cumulative travel distance D from the start of the initial travel of the vehicle 1 is calculated in real time (or at every predetermined calculation cycle).

In step S310, it is determined whether the cumulative traveling distance D has reached the threshold distance _{D_th} . When the cumulative traveling distance D has not reached the threshold distance _{D_th} (No), the control proceeds to step S320. On the other hand, when the cumulative traveling distance D has reached the threshold distance _{D_th} (Yes), the present control proceeds to step S380, the normal time EGR control is made valid (the EGR prohibition mode is made invalid), and then the process ends.

When the process proceeds from step S310 to step S320, that is, when the cumulative traveling distance D does not reach the threshold distance _{D_th} , it is determined whether the vehicle speed V exceeds the threshold speed _{V_th} . If the vehicle speed V exceeds the threshold speed _{V_th} (Yes), the control proceeds to step S330, the normal time EGR control is enabled, and then the process _returns to step S300. That is, during the period in which the vehicle speed V reaches the threshold speed _{V_th} even before the cumulative traveling distance D reaches the threshold distance _{D_th} , the normal time EGR control is temporarily enabled (permitted) over the period. To do.

On the other hand, in step S320, when the vehicle speed V does not exceed the threshold speed _{V_th} (No), the control proceeds to step S340 and prohibits the execution of the normal EGR control (keeps the EGR valve 53 fully closed). Then, the process returns to step S300. That is, before the cumulative traveling distance D reaches the threshold distance _{D_th} and the vehicle speed V is lower than the threshold speed _{V_th} , execution of the normal time EGR control is prohibited.

According to the third embodiment described in detail above, the execution of the normal time EGR control is prohibited from the start of the initial travel of the vehicle 1 until the cumulative travel distance D reaches the threshold distance _{D_th} . .. That is, during a period until the vehicle 1 is frequently repeatedly moved for a short distance and the temperature of the engine 10 is unlikely to rise, execution of the EGR control at normal time is prohibited, so that the condensed water generated by cooling the EGR gas is prohibited. It is configured so that it can be effectively suppressed. This makes it possible to prevent the corrosive condensed water from remaining in the cylinder C and the intake system, and effectively prevent the inside of the engine 10 and the intake system from being corroded.

Further, even before the cumulative travel distance D from the start of the initial travel of the vehicle 1 reaches the threshold distance _{D_th} , the EGR prohibit mode is set for the period in which the vehicle speed V exceeds the threshold speed _{V_th.} It is configured to be released and to temporarily enable (permit) the execution of the EGR control at the normal time. As a result, even before the cumulative travel distance D reaches the threshold distance _{D_th} , if the vehicle speed V exceeds the threshold speed _{V_th} for suppressing the generation of condensed water, the normal time EGR control is appropriately performed. As a result, deterioration of exhaust emission performance can be effectively suppressed.

[Fourth Embodiment]
FIG. 7 is a diagram illustrating a flow of EGR reduction processing according to the fourth embodiment. In the fourth embodiment, the determination process of step S220 shown in FIG. 5 of the second embodiment is replaced with step S420 of determining whether or not the vehicle speed V exceeds a predetermined threshold speed _{V_th} . Here, similarly to the third embodiment, the threshold speed _{V_th} is set based on a vehicle speed (for example, about 80 km/h) that can raise the cooling water temperature T to a predetermined high water temperature at which the generation of condensed water is suppressed. do it.

Hereinafter, the flow of the EGR reduction process according to the fourth embodiment will be described based on FIG. 7.

In step S400, the cumulative travel distance D from the start of the initial travel of the vehicle 1 is calculated in real time (or at every predetermined calculation cycle).

In step S410, it is determined whether the cumulative traveling distance D has reached the threshold distance _{D_th} . When the cumulative traveling distance D has not reached the threshold distance _{D_th} (No), the control proceeds to step S420. On the other hand, when the cumulative traveling distance D has reached the threshold distance _{D_th} (Yes), the control proceeds to step _S480 , the normal time EGR control is enabled (the EGR rate reduction mode is disabled), and then the process ends.

When the process proceeds from step S410 to step S420, that is, when the cumulative traveling distance D does not reach the threshold distance _{D_th} , it is determined whether the vehicle speed V exceeds the threshold speed _{V_th} . When the vehicle speed V exceeds the threshold speed _{V_th} (Yes), the control proceeds to step S430, the normal time EGR control is validated, and then the process _returns to step S400. That is, even before the cumulative travel distance D reaches the threshold distance _{D_th} , during the period in which the vehicle speed V reaches the threshold speed _{V_th} , the normal time EGR control is temporarily enabled (permitted) over the period. To

On the other hand, when the vehicle speed V does not exceed the threshold speed _{V_th} in step S420 (No), the control proceeds to step S440, and the reduction correction for reducing the target EGR rate of the EGR map M1 is performed, and then in step S400. Returned to processing. That is, before the cumulative traveling distance D reaches the threshold distance _{D_th} and the vehicle speed V does not exceed the threshold speed _{V_th} , the reduction correction for lowering the target EGR rate than the normal EGR control is executed. Become so.

According to the fourth embodiment described in detail above, from the start of the initial travel of the vehicle 1 until the cumulative travel distance D reaches the threshold distance _{D_th} , the EGR rate for correcting the target EGR rate in accordance with the cooling water temperature T is reduced. While the reduction mode is enabled, the EGR rate reduction mode is temporarily released during the period when the vehicle speed V exceeds the threshold velocity _{V_th} . This makes it possible to effectively prevent corrosive condensed water from remaining in the cylinder C or in the intake system, and effectively prevent corrosion in the engine 10 or the intake system. Further, even when the vehicle speed V does not reach the threshold speed _{V_th} , it is possible to effectively prevent a significant deterioration of the exhaust emission performance by operating at a low EGR rate without completely prohibiting the EGR control. it can.

[Other]
It should be noted that the present disclosure is not limited to the above-described embodiment, and may be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, as shown in FIG. 8, the determination of step S320 of the third embodiment may be incorporated as step S115 in the EGR prohibiting process flow (see FIG. 3) according to the first embodiment. In this configuration, the EGR of step S140 is performed only when the cooling water temperature T does not exceed the threshold water temperature _{T_th} (the cooling water temperature is low) and the vehicle speed V does not reach the threshold speed _{V_th} (the vehicle speed is low). Carry out prohibition processing. As a result, even in a vehicle whose traveling distance to the vehicle is short, the EGR reduction correction process can be executed only in the low-speed transportation state after vehicle production. That is, the deterioration of exhaust emission is limited to only during transportation before delivery, and EGR is enabled during high-speed traveling in which a relatively large amount of exhaust emission occurs, and the deterioration of exhaust emission is further minimized while the engine 10 internal It is possible to effectively prevent corrosion of the intake system.

Further, as shown in FIG. 9, the determination of step S420 of the fourth embodiment may be incorporated as step S215 in the EGR reduction processing flow according to the second embodiment (see FIG. 5). In this configuration, the EGR of step S140 is performed only when the cooling water temperature T does not exceed the threshold water temperature _{T_th} (the cooling water temperature is low) and the vehicle speed V does not reach the threshold speed _{V_th} (the vehicle speed is low). A reduction correction process is performed. As a result, even in a vehicle whose traveling distance to the vehicle is short, the EGR reduction correction process can be executed only in the low-speed transportation state after vehicle production. That is, the deterioration of exhaust emission is limited to only during transportation before delivery, and EGR is enabled during high-speed traveling in which a relatively large amount of exhaust emission occurs, and the deterioration of exhaust emission is further minimized while the engine 10 internal It is possible to effectively prevent corrosion of the intake system.

Further, although the above embodiment has been described as using the cumulative traveling distance D of the vehicle 1, the determination may be performed based on the cumulative traveling time of the vehicle 1.

1 Vehicle 10 Engine 20 Intake Manifold 21 Intake Passage 25 Exhaust Manifold 26 Exhaust Passage 50 EGR Device (Exhaust Gas Recirculation Device)
51 EGR passage 53 EGR valve 90 Water temperature sensor 91 Engine speed sensor (operating state acquisition means)
92 Fuel injection amount acquisition unit (operating state acquisition means)
93 Vehicle speed sensor (cumulative running distance acquisition means)
100 ECU
110 Cumulative mileage calculation unit (cumulative mileage acquisition means)
120 EGR control unit (control means)
130 EGR prohibition processing unit (limitation means)
140 EGR Prohibition Release Unit 170 EGR Reduction Correction Unit (Limiting Unit)
180 EGR reduction release section

Claims (5)

An engine mounted on the vehicle,
An exhaust gas recirculation device for recirculating at least a part of the exhaust gas of the engine to the intake system,
An operating state acquisition means for acquiring the operating state of the engine;
Control means for executing exhaust gas recirculation control for controlling the exhaust gas recirculation rate or recirculation amount by the exhaust gas recirculation device based on the acquired operating state,
An accumulated traveling amount acquisition means for acquiring the accumulated traveling amount of the vehicle,
During the period from the start of the initial running of the vehicle until the accumulated travel amount acquired reaches a predetermined threshold travel amount, the execution of the exhaust gas recirculation control is prohibited or the exhaust gas by the exhaust gas recirculation control is exhausted. A recirculation rate or a limiting means for reducing the recirculation amount. The limiting means, even before the cumulative travel amount reaches the threshold travel amount, if the cooling water temperature of the engine exceeds a predetermined threshold water temperature and no condensed water is generated, The engine device according to claim 1, wherein execution of exhaust gas recirculation control is permitted. In the case of reducing the exhaust gas recirculation rate or the recirculation amount by the exhaust gas recirculation control, the limiting unit greatly reduces the recirculation rate or the recirculation amount as the cooling water temperature of the engine decreases. The engine device according to 1 or 2. The limiting means causes the exhaust gas recirculation control by the control means to be executed while the vehicle speed of the vehicle exceeds a predetermined threshold vehicle speed even before the accumulated travel amount reaches the threshold travel amount. Allow the engine device according to any one of claims 1 to 3. An engine mounted on a vehicle, an exhaust gas recirculation device that recirculates at least a part of the exhaust gas of the engine to an intake system, and an exhaust gas recirculation rate by the exhaust gas recirculation device based on an operating state of the engine, or A control method of an engine device, comprising: a control unit that executes an exhaust gas recirculation control that controls a recirculation amount,
While acquiring the accumulated travel amount from the start of the initial running of the vehicle, until the acquired accumulated travel amount reaches a predetermined threshold travel amount, prohibit the execution of the exhaust gas recirculation control, or A method for controlling an engine device, comprising reducing an exhaust gas recirculation rate or a recirculation amount by the exhaust gas recirculation control.

Images