JP2016196828A - Addition liquid supply device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an addition liquid supply device for an internal combustion engine that can prevent deterioration of addition liquid in an addition valve and an addition liquid passage due to exhaust gas.SOLUTION: An engine 1 includes: a tank 210 for storing urea water; an urea addition valve 230 for injecting urea water into an exhaust passage 26; an urea water passage 240 for supplying the urea water in the tank 210 to the urea addition valve 230; and a pump 220 provided in the middle of the urea water passage 240. After stop of the engine, an urea addition control device 90 executes recovery control for recovering the urea water in the urea addition valve 230 and the urea water passage 240 to the tank 210 by driving the pump 220 with the urea addition valve 230 opened. When a starter 29 is driven while the recovery control has not been completed, an engine control device 80 closes the urea addition valve 230 through the urea addition control device 90.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an additive liquid supply apparatus for an internal combustion engine.

  For example, as described in Patent Document 1, there is known an apparatus that supplies an additive liquid to a catalyst that purifies nitrogen oxide (NOx) in exhaust gas. This additive liquid supply device includes a tank for storing urea water as an additive liquid used for NOx purification in the catalyst, an addition valve for injecting the additive liquid in the tank into the exhaust passage during engine operation, An additive liquid passage for supplying the additive liquid to the addition valve and a pump provided in the middle of the additive liquid passage are provided.

  Incidentally, during operation of the engine, the additive solution is supplied from the tank to the addition valve via the additive solution passage, so that the additive solution passage and the addition valve are filled with the additive solution. When the engine operation is stopped, the supply of the additive liquid is stopped, but the additive liquid remains in the additive liquid passage and the addition valve. Therefore, when the outside air temperature is low, the additive liquid remaining in the additive liquid passage or the addition valve may be frozen.

  Therefore, after the engine is stopped, recovery control is performed to recover the additive liquid remaining in the addition valve and the additive liquid passage to the tank by driving the pump while the addition valve is opened ( For example, Patent Document 1).

JP 2013-113267 A

By the way, when the above-described recovery control is not completed, the additive liquid exists in the addition valve and the additive liquid passage.
Thus, when the engine is started in a state where the additive liquid exists in the addition valve and the additive liquid passage and the exhaust gas flows into the exhaust passage, the addition valve is in the open state. Then, since exhaust gas flows into the addition valve, the additive liquid in the addition valve or the additive liquid passage may be deteriorated by the exhaust gas.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an additive liquid supply apparatus for an internal combustion engine that can suppress deterioration of the additive liquid in the addition valve and the additive liquid passage due to exhaust. There is to do.

  An additive liquid supply device for an internal combustion engine that solves the above problems includes a tank that stores the additive liquid, an addition valve that injects the additive liquid into an exhaust passage of the internal combustion engine, and the additive liquid in the tank to the addition valve. An additive liquid passage to be supplied and a pump provided in the middle of the additive liquid passage are provided, and the pump is driven in a state in which the addition valve is opened, whereby the addition valve passage and the additive liquid passage are provided. The collection control for collecting the added liquid in the tank is executed after the engine is stopped. The additive solution supply device is configured to close the addition valve when the starter for starting the engine is driven in a state where the recovery control is not completed.

  Combustion of the air-fuel mixture does not start as soon as the starter for starting the engine is driven. Normally, after a certain amount of cranking period, combustion of the air-fuel mixture starts and exhaust flows into the exhaust passage. To come. Therefore, if the addition valve is closed when the starter for starting the engine is driven, the addition valve can be closed before the inflow of exhaust gas into the exhaust passage starts.

  Therefore, in this configuration, when the start control for starting the engine is driven in a state where the collection control is not completed and the additive solution is present in the additive valve and the additive solution passage, the additive valve is closed. The valve state is set. Therefore, even when the flow of the exhaust gas into the exhaust passage starts after the starter is driven, the addition valve is in the closed state, so that the inflow of the exhaust gas into the addition valve is suppressed. Therefore, it can suppress that the addition liquid in an addition valve or an addition liquid channel deteriorates by exhaust.

The schematic diagram which shows schematic structure of the engine to which one Embodiment of the addition liquid supply apparatus of the internal combustion engine was applied. The time chart which shows the basic operation | movement of urea water addition in the embodiment. The flowchart which shows the procedure of the setting process of the pump starting request flag in the embodiment. The time chart which shows the operation | movement of urea water addition in the embodiment.

Hereinafter, an embodiment in which an additive liquid supply device for an internal combustion engine is applied to a diesel engine (hereinafter referred to as an “engine”) mounted on a vehicle will be described with reference to FIGS.
As shown in FIG. 1, the engine 1 is provided with a plurality of cylinders # 1 to # 4. A plurality of fuel injection valves 4 a to 4 d are attached to the cylinder head 2. These fuel injection valves 4a to 4d inject fuel into the combustion chambers of the corresponding cylinders # 1 to # 4. Also, the cylinder head 2 is provided with intake ports for introducing fresh air into the cylinders and exhaust ports 6a to 6d for discharging combustion gas to the outside of the cylinders corresponding to the respective cylinders # 1 to # 4. It has been.

A starter 29 for starting the engine is disposed on the crankshaft of the engine 1.
The fuel injection valves 4a to 4d are connected to a common rail 9 that accumulates high-pressure fuel. The common rail 9 is connected to the supply pump 10. The supply pump 10 sucks fuel in the fuel tank and supplies high-pressure fuel to the common rail 9. The high-pressure fuel supplied to the common rail 9 is injected into the cylinder from the fuel injection valves 4a to 4d when the fuel injection valves 4a to 4d are opened.

  An intake manifold 7 is connected to the intake port. The intake manifold 7 is connected to the intake passage 3. An intake throttle valve 16 for adjusting the intake air amount is provided in the intake passage 3. The intake throttle valve 16 is adjusted in opening degree by an actuator 17.

An exhaust manifold 8 is connected to the exhaust ports 6a to 6d. The exhaust manifold 8 is connected to the exhaust passage 26.
In the middle of the exhaust passage 26, there is provided a turbocharger 11 for supercharging intake air introduced into the cylinder using exhaust pressure. An intercooler 18 is provided in the intake passage 3 between the intake side compressor of the turbocharger 11 and the intake throttle valve 16. The intercooler 18 cools the intake air whose temperature has risen due to supercharging of the turbocharger 11.

  A first purification member 30 that purifies the exhaust gas is provided in the middle of the exhaust passage 26 and downstream of the exhaust side turbine of the turbocharger 11. Inside the first purification member 30, an oxidation catalyst 31 and a DPF catalyst 32 are arranged in series with respect to the flow direction of the exhaust gas.

  The oxidation catalyst 31 carries a catalyst for oxidizing HC in the exhaust. The DPF catalyst 32 is a filter that collects PM (particulate matter) in the exhaust gas and is composed of a porous ceramic, and further supports a catalyst for promoting oxidation of PM. . The PM in the exhaust gas is collected when it passes through the porous wall of the DPF catalyst 32.

  Further, a fuel addition valve 5 for supplying fuel as an additive to the oxidation catalyst 31 and the DPF catalyst 32 is provided in the vicinity of the collecting portion of the exhaust manifold 8. The fuel addition valve 5 is connected to the supply pump 10 through a fuel supply pipe 27. The position of the fuel addition valve 5 can be changed as appropriate as long as it is in the exhaust system and upstream of the first purification member 30.

  A second purification member 40 that purifies the exhaust gas is provided in the middle of the exhaust passage 26 and downstream of the first purification member 30. Inside the second purification member 40, a selective reduction type NOx catalyst (hereinafter referred to as SCR catalyst) 41 is disposed as an exhaust purification catalyst that reduces and purifies NOx in exhaust using a reducing agent.

  Further, a third purification member 50 for purifying exhaust gas is provided in the middle of the exhaust passage 26 and downstream of the second purification member 40. Inside the third purification member 50, an ammonia oxidation catalyst 51 for purifying ammonia in the exhaust is disposed.

  The engine 1 is provided with a urea water supply mechanism 200 that supplies urea water as a reducing liquid to the SCR catalyst 41. The urea water supply mechanism 200 is connected to a tank 210 that stores urea water, a urea addition valve 230 that injects urea water into the exhaust passage 26, a urea addition valve 230, and the tank 210. Is supplied to the urea addition valve 230, and a pump 220 and the like provided in the middle of the urea water passage 240.

  The urea water supply mechanism 200 is provided with a heater for thawing frozen urea water and suppressing freezing of urea water. For example, in the present embodiment, heaters are provided in the tank 210, the urea water passage 240, and the pump 220, respectively.

  The urea addition valve 230 is provided in the exhaust passage 26 between the first purification member 30 and the second purification member 40, and the injection hole is opened toward the SCR catalyst 41. When the valve portion of the urea addition valve 230 is opened, urea water is injected into the exhaust passage 26 via the urea water passage 240.

  The pump 220 is an electric pump, and at the time of forward rotation, the urea water is fed from the tank 210 toward the urea addition valve 230. On the other hand, during reverse rotation, urea water is sent from the urea addition valve 230 toward the tank 210. That is, during reverse rotation of the pump 220, urea water is collected from the urea addition valve 230 and the urea water passage 240 and returned to the tank 210.

  A dispersion plate 60 is provided in the exhaust passage 26 between the urea addition valve 230 and the SCR catalyst 41 to promote atomization of the urea water by dispersing the urea water injected from the urea addition valve 230. It has been.

  The urea water injected from the urea addition valve 230 is converted to ammonia by hydrolysis using exhaust heat and is adsorbed by the SCR catalyst 41. Then, NOx is reduced and purified by the ammonia adsorbed on the SCR catalyst 41.

  In addition, the engine 1 is provided with an exhaust gas recirculation device (hereinafter referred to as an EGR device). This EGR device is a device that reduces the combustion temperature in the cylinder by introducing a part of the exhaust gas into the intake air, thereby reducing the amount of NOx generated. This exhaust gas recirculation device includes an EGR passage 13 that communicates the intake passage 3 and the exhaust manifold 8, an EGR valve 15 provided in the EGR passage 13, an EGR cooler 14, and the like. By adjusting the opening degree of the EGR valve 15, the exhaust gas recirculation amount introduced into the intake passage 3 from the exhaust passage 26, that is, the so-called external EGR amount is adjusted. Further, the temperature of the exhaust gas flowing through the EGR passage 13 is lowered by the EGR cooler 14.

  Various sensors and switches for detecting the engine operating state are attached to the engine 1. For example, the air flow meter 19 detects the intake air amount GA in the intake passage 3. The throttle valve opening sensor 20 detects the opening of the intake throttle valve 16. The crank angle sensor 21 detects the rotation angle of the crankshaft, and the engine rotation speed NE is calculated based on the detection signal. The accelerator operation amount sensor 22 detects an amount of depression of an accelerator pedal (accelerator operation member), that is, an accelerator operation amount ACCP. The outside air temperature sensor 23 detects the outside air temperature THout. The vehicle speed sensor 24 detects the vehicle speed SPD of the vehicle on which the engine 1 is mounted. The ignition switch (IG) 25 detects a start operation and a stop operation of the engine 1 by a vehicle driver.

  The first exhaust temperature sensor 100 provided upstream of the oxidation catalyst 31 detects the first exhaust temperature TH1 that is the exhaust temperature before flowing into the oxidation catalyst 31. Between the oxidation catalyst 31 and the DPF catalyst 32, a second exhaust temperature sensor 120 that detects a second exhaust temperature TH2 that is an exhaust temperature before flowing into the DPF catalyst 32 is provided. The differential pressure sensor 110 detects the pressure difference ΔP between the exhaust pressure upstream and downstream of the DPF catalyst 32.

  A third exhaust temperature sensor 130 is provided in the exhaust passage 26 between the first purification member 30 and the second purification member 40 and upstream of the urea addition valve 230. The third exhaust temperature sensor 130 detects a third exhaust temperature TH3 that is the exhaust temperature before flowing into the SCR catalyst 41.

  In the exhaust passage 26 downstream of the third purification member 50, after passing through the SCR catalyst 41, the fourth exhaust temperature sensor 140 that detects the fourth exhaust temperature TH 4 that is the exhaust temperature after passing through the SCR catalyst 41. A NOx sensor 150 for detecting NOx concentration Naf in the exhaust gas is provided.

  Outputs of these various sensors are input to the engine control device 80. The engine control device 80 includes a central processing control device (CPU), a read-only memory (ROM) that stores various programs and maps in advance, a random access memory (RAM) that temporarily stores calculation results of the CPU, a timer counter, and the like. The microcomputer is mainly configured with an input interface and an output interface.

  Then, the engine controller 80 controls, for example, the fuel injection amount control / fuel injection timing control of the fuel injection valves 4a to 4d and the fuel addition valve 5, the discharge pressure control of the supply pump 10, and the actuator 17 for opening and closing the intake throttle valve 16. Various controls of the engine 1 such as drive amount control and opening degree control of the EGR valve 15 are performed.

  The engine control device 80 automatically stops the engine 1 when a predetermined automatic stop condition is satisfied, and so-called automatic stop automatic start control that automatically starts the engine 1 when a predetermined automatic start condition is satisfied. Also execute.

  The engine control device 80 communicates with the urea addition control device 90 via the communication line 300 such as various control values and flag values. This urea addition control device 90 is also composed of a central processing control device (CPU), a read only memory (ROM) preliminarily storing various programs and maps, a random access memory (RAM) temporarily storing CPU calculation results, and a timer. The microcomputer is mainly configured with a counter, an input interface, an output interface, and the like.

  The urea addition control device 90 performs various controls of the urea water supply mechanism 200 such as drive control of the urea addition valve 230, drive control of the pump 220, and heater drive of the urea water supply mechanism 200, for example.

  Further, the engine control device 80 and the urea addition control device 90 perform urea water addition control by the urea addition valve 230 as one of exhaust purification control. In this addition control, the engine control device 80 calculates a urea addition amount without excess or deficiency in order to reduce NOx discharged from the engine 1 based on the engine operating state and the like. The calculated urea addition amount is input to the urea addition control device 90 via the communication line 300. The urea addition control device 90 controls the open state of the urea addition valve 230 so that the input urea addition amount is injected from the urea addition valve 230.

Thus, during the operation of the engine 1, urea water is injected to purify NOx. When the engine 1 is stopped, the urea water injection is also stopped.
By the way, as described above, when the engine operation is stopped, urea water addition is also stopped. However, if urea water remains in the urea addition valve 230 or the urea water passage 240, the outside air temperature is low. In such cases, the remaining urea water may freeze. Therefore, in order to suppress such freezing of urea water, the urea addition control device 90 is in the urea addition valve 230 or the urea water after the engine is stopped and the mutual communication with the engine control device 80 is interrupted. Recovery control for recovering the urea water in the passage 240 to the tank 210 is performed. In this recovery control, the pump 220 is driven in the opposite direction to the urea water addition performed during engine operation, and the urea addition valve 230 is held open. As a result, the urea water remaining in the urea addition valve 230 and the urea water passage 240 is recovered in the tank 210.

  Further, when such recovery control is performed after the engine is stopped, the next time the engine is started and urea addition is started, an accurate amount is maintained until the urea addition valve 230 and the urea water passage 240 are filled with urea water. Urea water cannot be injected. Therefore, after the engine is started, before the urea water addition for NOx purification is started, filling control for filling the urea addition valve 230 and the urea water passage 240 with the urea water is also performed.

FIG. 2 shows the basic operation of urea water addition according to the present embodiment including recovery control and filling control.
When the ignition switch 25 is turned off at time t1, the engine control device 80 changes the pump start request flag for requesting the urea addition control device 90 to start the pump 220 from “ON” to “OFF”. At the same time, the urea addition preparation request flag for requesting preparation of urea water addition is changed from “ON” to “OFF”. This urea addition preparation request flag is a flag for instructing the urea addition control device 90 to start the above-described filling control. For example, when the temperature of the SCR catalyst 41 reaches a temperature required for NOx purification, it is turned “ON”. Is set. On the other hand, for example, when the temperature of the SCR catalyst 41 becomes lower than the temperature required for NOx purification, or when the ignition switch 25 is turned off, the urea addition preparation request flag is set to “OFF”.

  Further, when the ignition switch 25 is turned off, the fuel injection is stopped and the engine is stopped. As a result, the engine rotational speed NE decreases, and the engine rotational speed NE is lower than a predetermined first threshold value NE1. Then, the engine control device 80 changes the after-engine-start determination flag from “ON” to “OFF”.

  When the ignition switch 25 is turned off, the mutual communication between the engine control device 80 and the urea addition control device 90 is cut off, and the urea addition control device 90 stops driving the pump 220 and urea. The addition valve 230 is closed. Then, when a predetermined period has elapsed after the ignition switch 25 is turned off, the urea addition control device 90 autonomously executes the recovery control for a predetermined period. That is, the reverse rotation of the pump 220 and the opening of the urea addition valve 230 are executed for a predetermined period, and the urea water remaining in the urea addition valve 230 and the urea water passage 240 is collected in the tank 210. During the execution of the collection control, a flag indicating the state of the collection control is changed from a value indicating “not executed” (for example, “1”) to a value indicating “in execution” (for example, “2”) . The flag indicating the state of the recovery control is set by the urea addition controller 90.

  When the collection control is executed for a predetermined period, the urea addition control device 90 stops driving the pump 220 and closes the urea addition valve 230 to complete the collection control. When the collection control is completed in this manner, a flag indicating the state of the collection control is set to a value indicating “complete” (for example, “3”).

When the ignition switch 25 is turned on at time t2, mutual communication between the engine control device 80 and the urea addition control device 90 is started.
When the ignition switch 25 is turned on, the starter 29 is driven and fuel injection is started, so that the engine speed NE starts to increase. Then, at time t3, when the engine rotational speed NE exceeds the second threshold value NE2 set to a rotational speed higher than the first threshold value NE1, it becomes possible to determine that the engine 1 has been started. The engine control device 80 changes the post-engine start flag from “OFF” to “ON”.

  When the ignition switch 25 is turned on and the after-starting engine flag is “ON”, the engine control device 80 changes the pump activation request flag from “OFF” to “ON”.

  When receiving the value of the pump activation request flag in the “ON” state from the engine controller 80, the urea addition control device 90 starts a series of processes in accordance with the pump activation request. Note that the execution priority of the series of processes in response to the pump activation request is set higher than the above-described collection control.

  As a series of processes in response to the pump activation request, first, the urea addition control device 90 determines whether or not to drive the heater provided in the urea water supply mechanism 200 based on the outside air temperature or the like. When the heater needs to be driven, the heater is driven to thaw urea water. When the driving of the heater is completed, or when it is determined that the driving of the heater is unnecessary, the pump 220 is once rotated in the reverse direction to check the operation.

  When it is confirmed that there is no abnormality in the driving of the pump 220 by performing such an operation check, the urea addition control device 90 receives the value of the urea water addition preparation request flag in the “ON” state from the engine control device 80. Then, the above-described filling control is started.

  When this filling control is started, the pump 220 is driven in a normal rotation state. Then, the urea addition valve 230 is intermittently opened and closed to release air, so that the urea addition valve 230 and the urea water passage 240 are filled with urea water and filling is completed. When this filling process is started, a flag indicating the state of the collection control is set to a value (for example, “1”) indicating “not implemented”.

  When the filling of the urea water is completed, the urea addition control device 90 keeps the urea addition valve 230 in a closed state, thereby increasing the pressure of the urea water in the urea water passage 240, and urea in the urea water passage 240. When the water pressure reaches the specified pressure, the drive control of the pump 220 is performed so that the pressure reaching the specified pressure is maintained. Further, when the pressure of the urea water in the urea water passage 240 is maintained at the specified pressure in this way, the urea addition controller 90 responds to the urea addition amount calculated by the engine controller 80. Urea addition, that is, urea addition for NOx purification is performed.

  By the way, when the above-described recovery control is not completed, urea water exists in the urea addition valve 230 and the urea water passage 240. Thus, when the engine is started in a state where urea water exists in the urea addition valve 230 and the urea water passage 240 and exhaust gas flows into the exhaust passage 26, the urea addition valve 230 is opened. When in the valve state, the exhaust gas flows into the urea addition valve 230, so that the urea water in the urea addition valve 230 and the urea water passage 240 may be deteriorated by the exhaust gas.

  Therefore, in the present embodiment, the condition for starting the series of processes in accordance with the pump activation request that is set to have a higher execution priority than the recovery control described above, that is, the pump activation request flag is set to “ON”. By optimizing the conditions, the deterioration of the urea water due to the exhaust gas is suppressed.

FIG. 3 shows the procedure for setting the pump activation request flag. This setting process is repeatedly executed at predetermined intervals by the engine control device 80.
When this process is started, it is determined whether or not all of the following preconditions A to C are satisfied (S100).

Precondition A: The ignition switch 25 is “ON”.
Precondition B: At least one of the following preconditions B1 to B4 is satisfied.
Precondition B1: There is a history of starter ON, and the state of the recovery control is “in execution”, “interrupted”, or “not implemented”.

  In the precondition B1, whether or not there is a starter ON history is determined based on the starter ON history flag. The starter ON history flag is set to “ON” when the starter driving can be confirmed because the starter driving is continuously performed for a predetermined time. Therefore, when the starter ON history flag is “ON”, it is determined that there is a starter ON history. On the other hand, when the ignition switch 25 is turned off, the starter ON history flag is set to “OFF”.

  In addition, in the precondition B1, whether the state of the collection control is “in execution”, “suspended”, or “not implemented” determines whether or not the collection control has been completed. Yes, based on the value of a flag indicating the state of recovery control. Note that the value of the flag indicating the state of the collection control is set to, for example, “2” if “in execution”, “4” if “suspended”, or “1” if “not implemented”. Is done. When the state of the collection control is “in execution”, “suspended”, or “not implemented”, it is determined that the collection control is not completed.

Precondition B2: After engine start.
In this precondition B2, it is determined that the engine has been started when the after-start flag is set to “ON”, that is, when the engine speed NE exceeds the second threshold value NE2. The

Precondition B3: An engine stall is occurring.
In precondition B3, whether or not an engine stall is occurring is determined based on an engine stall determination flag. This engine stall determination flag is set to “ON” when the following conditions 1 to 3 are all satisfied.

Condition 1: the ignition switch 25 is ON.
Condition 2: There is a history in which the flag after engine start is set to “ON” after the ignition switch 25 is turned on.

Condition 3: The automatic stop is not executed and the current after engine start flag is “OFF”.
On the other hand, for example, when the engine start flag is changed from “OFF” to “ON”, the engine stall determination flag is set to “OFF”. When the engine stall determination flag is “ON”, it is determined that an engine stall is occurring.

Precondition B4: Automatic stop is in progress.
Precondition C: All other conditions are satisfied.
Examples of the “other various conditions” in the precondition C include the following conditions.

Environmental conditions (for example, the outside air temperature is not excessively low, the atmospheric pressure is not excessively low, etc.) suitable for the execution of urea water addition are established.
• Fail-safe is not in progress (except when restarting to detect pump abnormality).

When all the preconditions A to C are satisfied (S100: YES), the pump request flag is set to “ON” (S110), and this process is terminated.
On the other hand, when at least one of the preconditions A to C is not satisfied (S100: NO), the pump request flag is set to “OFF” (S110), and this process is terminated.

  Next, with reference to the urea water addition operation shown in FIG. 4, the operation of the pump start request flag setting process will be described. In the state shown in FIG. 4, it is assumed that the precondition C is satisfied.

  At time t1 shown in FIG. 4, the state of the engine post-start flag when the ignition switch 25 is turned off, the state of the pump activation request flag, the state of the urea water addition preparation request flag, the state of the heater of the urea water supply mechanism 200 The state of the pump 220, the state of the urea addition valve 230, and the state of recovery control are the same as those shown in FIG.

  Similarly to the basic operation shown in FIG. 2, when the ignition switch 25 is turned off at time t1, the mutual communication between the engine control device 80 and the urea addition control device 90 is interrupted. The urea addition controller 90 stops driving the pump 220 and closes the urea addition valve 230. Then, when a predetermined period has elapsed after the ignition switch 25 is turned off, the urea addition control device 90 autonomously executes the recovery control for a predetermined period. That is, the reverse rotation of the pump 220 and the opening of the urea addition valve 230 are executed for a predetermined period, and the urea water remaining in the urea addition valve 230 and the urea water passage 240 is collected in the tank 210. During the execution of the collection control, a flag indicating the collection state is set to a value (for example, “2”) indicating “being executed”.

  Here, when the recovery control is still being executed and the ignition switch 25 is turned on before the recovery control is completed (time t2), mutual communication between the engine control device 80 and the urea addition control device 90 is performed. Is started.

  When the ignition switch 25 is turned on, the starter 29 is driven, so that the engine control device 80 changes the starter ON history flag from “OFF” to “ON”.

  When the starter ON history flag is set to “ON” in this way, the precondition A, the precondition B (precondition B1), and the precondition C are all satisfied. Is changed from “OFF” to “ON” (time t3).

When receiving the value of the pump activation request flag in the “ON” state from the engine controller 80, the urea addition control device 90 starts a series of processes in accordance with the pump activation request.
As a series of processes in response to the pump activation request, first, the urea addition control device 90 determines whether or not to drive the heater provided in the urea water supply mechanism 200 based on the outside air temperature or the like. When the heater needs to be driven, the heater is driven to suppress, for example, urea water freezing. Then, after starting the heater driving or when it is determined that the heater driving is unnecessary, the pump 220 has already been reversely rotated by the recovery control. By omitting it, the pump 220 is stopped and the urea addition valve 230 is closed, thereby interrupting the recovery control that has been executed so far. When the collection control is interrupted in this way, the flag indicating the collection state is set to a value (for example, “4”) indicating “interruption”.

  Since it is a relatively short time from the start of driving the starter 29 to the closing of the urea addition valve 230 as one of a series of processes in accordance with the pump activation request, the time when the urea addition valve 230 is closed Then, the combustion of the air-fuel mixture has not occurred sufficiently, and almost no exhaust gas flows into the exhaust passage 26. Therefore, the urea addition valve 230 is closed before the exhaust gas starts to flow into the exhaust passage 26.

  Thereafter, when the urea addition control device 90 receives the value of the urea water addition preparation request flag in the “ON” state from the engine control device 80, the processing after the filling control described above is similarly performed. When this filling process is started, the flag indicating the state of the recovery control is changed from a value indicating “interrupted” to a value indicating “not implemented” (for example, “1”).

As described above, according to the present embodiment, the following effects can be obtained.
(1) When the starter 29 is driven, the combustion of the air-fuel mixture does not start immediately. Normally, after a certain amount of cranking period, the combustion of the air-fuel mixture is started and exhaust gas is discharged into the exhaust passage 26. Inflow. Accordingly, if the urea addition valve 230 is closed when the starter 29 is driven, the urea addition valve 230 can be closed before the inflow of exhaust gas into the exhaust passage 26 starts.

  Therefore, by setting the precondition B1, when the starter 29 is driven in a state where the recovery control is not completed and urea water is present inside the urea addition valve 230 and the urea water passage 240, The pump activation request flag is set to “ON”. When the pump activation request flag is set to “ON”, the urea addition valve 230 that has been opened by the recovery control is closed. Therefore, even when the flow of exhaust gas into the exhaust passage 26 starts after the starter 29 is driven, the urea addition valve 230 is in a closed state, so that the inflow of exhaust gas into the urea addition valve 230 is suppressed. Therefore, it is possible to prevent the urea water in the urea addition valve 230 and the urea water passage 240 from deteriorating due to exhaust.

  (2) By setting the precondition B2, the engine 1 is not completely started even when the ignition switch 25 is turned on (for example, when the starter 29 is stopped before the engine 1 is started) Etc.), the pump activation request flag is set to “OFF”. Therefore, it is possible to prevent a series of processes corresponding to the pump activation request for performing urea water addition described above from being performed wastefully even though the engine 1 is not started.

  (3) When an engine stall occurs or when automatic stop is executed, the engine 1 has already been started before such a state is reached, so the pump activation request flag is set to “ON”. Further, when the engine stall occurs or when the automatic stop is executed, the engine 1 is stopped, but the stop time is not so long, and the possibility that the engine 1 is started again is very high. high. Therefore, by setting the preconditions B3 and B4, the pump start request flag is kept “ON” when an engine stall occurs or when automatic stop is executed. . Therefore, it is possible to prevent the pump activation request flag from being unnecessarily changed from “OFF” to “ON”.

In addition, the said embodiment can also be changed and implemented as follows.
In the basic operation shown in FIG. 2, the operation check of the pump 220 is performed before the filling control is executed. However, the operation check may be performed at another time.

-The above precondition C may be omitted. Even in this case, the effects (1) to (3) can be obtained.
The above precondition B2 may be omitted. Even in this case, effects other than the above (2) can be obtained.

The precondition B3 and the precondition B4 may be omitted. Even in this case, effects other than the above (3) can be obtained.
The number of exhaust temperature sensors and the number of NOx sensors provided in the exhaust passage can be changed as appropriate.

The engine control device 80 and the urea addition control device 90 are provided, but each of these control devices may be configured by one control device.
The engine 1 is an internal combustion engine in which automatic stop automatic start control is executed, but may be an internal combustion engine in which such automatic stop automatic start control is not executed.

  Although urea water is used as the additive solution, other additive solutions may be used.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Cylinder head, 3 ... Intake passage, 4a-4d ... Fuel injection valve, 5 ... Fuel addition valve, 6a-6d ... Exhaust port, 7 ... Intake manifold, 8 ... Exhaust manifold, 9 ... Common rail, 10 DESCRIPTION OF SYMBOLS ... Supply pump, 11 ... Turbocharger, 13 ... EGR passage, 14 ... EGR cooler, 15 ... EGR valve, 16 ... Intake throttle valve, 17 ... Actuator, 18 ... Intercooler, 19 ... Air flow meter, 20 ... Throttle valve opening Sensor: 21 ... Crank angle sensor, 22 ... Accelerator operation amount sensor, 23 ... Outside air temperature sensor, 24 ... Vehicle speed sensor, 25 ... Ignition switch, 26 ... Exhaust passage, 27 ... Fuel supply pipe, 29 ... Starter, 30 ... First Purification member, 31 ... oxidation catalyst, 32 ... filter, 40 ... second purification member, 41 ... selective reduction type NOx catalyst SCR catalyst), 50 ... third purification member, 51 ... ammonia oxidation catalyst, 60 ... dispersion plate, 80 ... control device for engine, 90 ... control device for urea addition, 100 ... first exhaust temperature sensor, 110 ... differential pressure sensor , 120 ... second exhaust temperature sensor, 130 ... third exhaust temperature sensor, 140 ... fourth exhaust temperature sensor, 150 ... NOx sensor, 200 ... urea water supply mechanism, 210 ... tank, 220 ... pump, 230 ... urea addition valve , 240 ... urea water passage, 300 ... communication line.

Claims (1)

A tank for storing the additive liquid, an addition valve for injecting the additive liquid into the exhaust passage of the internal combustion engine, an additive liquid path for supplying the additive liquid in the tank to the addition valve, and in the middle of the additive liquid path And a recovery control for recovering the addition liquid in the addition valve and the addition liquid passage to the tank by driving the pump in a state where the addition valve is opened. An additive liquid supply device for an internal combustion engine to be executed after stopping,
An additive liquid supply apparatus for an internal combustion engine, wherein when the starter for starting the engine is driven in a state where the recovery control is not completed, the addition valve is closed.