JP2009097348A - Control device and control method for reducer supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and method for controlling a reducer supply system reducing energy consumption by immediately stopping a heating means when an internal combustion engine gets in an idling stop mode. <P>SOLUTION: The control device controlling the reducer supply system includes: an idling stop determination part determining whether the internal combustion engine is in the stop mode by idling stop control for automatically stopping the internal combustion engine; a heating means operation determination part determining whether a heating means provided in a reducer supply system for supplying a reducer injection valve with liquid reducer is operating; and a heating means control part stopping operation of the heating means if the internal combustion engine is in the automatic stop mode and the heating means is operating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device and a control method for a reducing agent supply system used in an exhaust purification device. In particular, the present invention relates to a control device and a control method for a reducing agent supply system used in a vehicle including an idling stop device.

Conventionally, exhaust gas discharged from an internal combustion engine such as a diesel engine contains nitrogen oxides (hereinafter referred to as “NO _X ”) that may affect the environment. As an exhaust gas purification apparatus used to purify the NO _X, the liquid reducing agent, such as urea aqueous solution on the upstream side of the disposed in the exhaust passage reduction catalyst injected and supplied into the exhaust gas, NO _X in a reducing catalyst An exhaust gas purification device (SCR system) that selectively reduces and purifies is known.

Here, the liquid reducing agent may freeze at a low temperature, and the reducing agent may not be supplied by injection. Therefore, there is an exhaust purification device in which heating means is provided in a storage tank or supply system for the liquid reducing agent to prevent the liquid reducing agent from freezing.
More specifically, a heating wire is arranged over the entire or main part of the storage tank and the supply pipe system of the liquid reducing agent, a heat insulating material enveloping layer is provided thereon, and the heating wire is also provided in the storage tank as necessary. Exhaust air that can be provided with heating means, and that can pass through these heating wires from the outside in accordance with the outside air temperature and / or the reducing agent temperature, and can maintain an appropriate temperature range that blocks the conduction and prevents the liquid reducing agent from freezing. A purification device is disclosed (see Patent Document 1).

Incidentally, in recent years, an idling stop device that automatically stops an internal combustion engine during a temporary stop of the internal combustion engine has been used in order to reduce exhaust from the internal combustion engine for the purpose of environmental protection and noise prevention. This idling stop device stops the internal combustion engine with the key switch turned on, and liquid reductant may be injected even though there is no exhaust flow. There has been proposed an idling stop device that works together.
More specifically, an operation region where there is no problem even if the engine is automatically stopped, the engine is stopped when the vehicle is temporarily stopped and the injection of the liquid reducing agent is continuously stopped for a predetermined time. An idling stop device is disclosed in which the solute of the liquid reducing agent is not deposited in the engine exhaust system (see Patent Document 2).

Japanese Patent Laid-Open No. 2000-27627 (full text, FIG. 1) JP 2006-118413 A (the whole sentence, FIG. 1)

However, according to the idling stop device described in Patent Document 2, the liquid reducing agent is not supplied to the engine exhaust system after the engine is automatically stopped, but the subsequent treatment of the reducing agent supply system is particularly considered. Not.
Further, in the idling stop state, the engine is stopped and the key switch remains on. Therefore, in the case of the exhaust gas purification device provided with the heating wire heating means of Patent Document 1, the outside air temperature and the reducing agent temperature are not limited even though the engine is stopped and the reducing agent injection control is not performed. If it is determined that the temperature has decreased, the heating wire heating means may operate. As a result, energy for operating the heating wire heating means is wasted.

  Accordingly, the inventors of the present invention diligently worked on a reducing agent supply system used in an exhaust gas purification apparatus for an internal combustion engine equipped with an idling stop device. When the internal combustion engine is in an automatic stop state by idling stop control, heating means is used. The present invention has been completed by finding that such a problem can be solved by stopping the operation. That is, an object of the present invention is to provide a control device and a control method for a reducing agent supply system that can reduce energy consumption by stopping heating means when the internal combustion engine is automatically stopped by idling stop control. It is to be.

  According to the present invention, the liquid reducing agent is injected and supplied to the exhaust upstream side of the reduction catalyst disposed in the exhaust passage of the internal combustion engine, and is used in an exhaust purification device that reduces and purifies nitrogen oxides in the exhaust with the reduction catalyst. A storage tank in which the liquid reducing agent is stored, a pump for pumping the liquid reducing agent in the storage tank, a reducing agent injection valve for controlling the supply amount of the liquid reducing agent pumped by the pump, and the liquid reducing agent A control device that controls a reducing agent supply system including a reducing agent supply passage that passes through the engine, and determines whether the internal combustion engine is stopped by idling stop control that automatically stops the internal combustion engine. A stop determination unit, a heating unit operation determination unit that determines whether or not the heating unit provided in the reducing agent supply system that supplies the liquid reducing agent to the reducing agent injection valve is operating, and the internal combustion engine is in the automatic stop state There is provided a controller for a reducing agent supply system, characterized by comprising a heating means control section for stopping the operation of the heating means when the heating means is in operation, and solves the above-mentioned problems can do.

  Further, in configuring the control device of the reducing agent supply system of the present invention, the heating means control unit may stop the operation of the heating means after a predetermined time has elapsed after it is determined that the internal combustion engine is in the automatic stop state. preferable.

  Further, in configuring the control device of the reducing agent supply system of the present invention, the controller includes an outside air temperature detection unit that detects outside air temperature information, and the heating means controller heats after the internal combustion engine is determined to be in the automatic stop state. It is preferable to change the time until the means is stopped according to the outside air temperature.

  In addition, when configuring the control device of the reducing agent supply system of the present invention, the controller includes an energy detection unit that detects the magnitude of energy supplied from the power source of the heating unit, and the heating unit control unit automatically stops the internal combustion engine. It is preferable to change the time from when it is determined to be in the state to when the heating means is stopped according to the magnitude of energy.

  Further, when configuring the control device of the reducing agent supply system of the present invention, a reducing agent return control unit for recovering the liquid reducing agent in the reducing agent supply system in the storage tank when the internal combustion engine is in the automatic stop state is further provided. It is preferable to provide.

  In configuring the control device of the reducing agent supply system of the present invention, the reducing agent return control unit may recover the liquid reducing agent after a predetermined time has elapsed after it is determined that the internal combustion engine is in the automatic stop state. preferable.

  Further, when configuring the control device of the reducing agent supply system of the present invention, the idling stop determination unit is in a state where at least the key switch of the internal combustion engine is on and the rotational speed of the internal combustion engine is equal to or less than a predetermined value. It is preferable to determine that the internal combustion engine is in an automatic stop state when it continues for a predetermined time.

  In configuring the control device for the reducing agent supply system of the present invention, the idling stop determination unit determines whether or not the internal combustion engine is in an automatic stop state based on a signal from the engine control device that controls the operation of the internal combustion engine. Is preferably determined.

  Another aspect of the present invention is an exhaust purification system in which a liquid reducing agent is injected and supplied to an exhaust upstream side of a reduction catalyst disposed in an exhaust passage of an internal combustion engine, and nitrogen oxides in exhaust gas are reduced and purified by the reduction catalyst. A storage tank in which the liquid reducing agent is stored, a pump for pumping the liquid reducing agent in the storage tank, and a reducing agent injection valve for controlling the supply of the liquid reducing agent pumped by the pump; A control method for a reducing agent supply system comprising a reducing agent supply passage through which a liquid reducing agent flows, wherein the internal combustion engine is stopped by idling stop control that automatically stops the internal combustion engine. It is a control method for a reducing agent supply system, wherein it is determined whether or not the provided heating means is operating, and when the heating means is operating, the operation of the heating means is stopped.

  According to the control device of the reducing agent supply system of the present invention, the key switch is turned on in order to include the heating unit operation control unit that stops the operation of the heating unit when the internal combustion engine is automatically stopped by the idling stop control. Nevertheless, the operation of the heating means in a state where the injection control of the reducing agent is not performed can be stopped, and wasteful consumption of energy can be suppressed.

  Further, in the control device of the reducing agent supply system of the present invention, after the internal combustion engine is automatically stopped by the idling stop control, the operation of the heating means is stopped after a predetermined time has elapsed, so that the idling stop mode can be performed in a short time. Is released and the internal combustion engine is restarted, the temperature of the reducing agent supply system does not decrease while the internal combustion engine is automatically stopped, and the liquid reducing agent is prevented from freezing.

  Further, in the control device of the reducing agent supply system of the present invention, after the internal combustion engine is automatically stopped by the idling stop control, the time until the operation of the heating unit is stopped is changed according to the outside air temperature, thereby reducing the liquid reduction. In a state where the agent is more likely to freeze, the heating means is operated for a relatively long time, while in a state where the agent is relatively difficult to freeze, the operation of the heating means is quickly stopped to waste energy. Can be suppressed.

  Further, in the control device of the reducing agent supply system of the present invention, after the internal combustion engine is automatically stopped by the idling stop control, the time until the operation of the heating means is stopped is the state of energy supplied from the power source of the heating means. If the remaining amount of energy is reduced, the heating means is stopped early, while if the remaining amount of energy is sufficient, the recovery state of the liquid reducing agent is taken into consideration. Thus, the timing of stopping the heating means can be measured.

  In the control device for the reducing agent supply system of the present invention, after the internal combustion engine is automatically stopped by the idling stop control, the liquid reducing agent in the reducing agent supply system is recovered in the storage tank, so that the key switch is turned on. It is possible to prevent the liquid reducing agent from freezing in the reducing agent supply system in a state in which the injection control of the reducing agent is not performed.

  In the control device of the reducing agent supply system of the present invention, the idling stop mode can be set in a short time by allowing the liquid reducing agent to be collected after a predetermined time has elapsed after the internal combustion engine is automatically stopped by the idling stop control. When the engine is released and the internal combustion engine is restarted, it is possible to quickly restart the injection of the liquid reducing agent.

  In the control device of the reducing agent supply system of the present invention, when the predetermined condition is satisfied, the internal combustion engine is automatically operated by the idling stop device by determining that the internal combustion engine is in the automatic stop state by the idling stop control. The heating means controller can be controlled in association with the timing of stopping.

  Further, in the control device of the reducing agent supply system of the present invention, the configuration of the control device is simplified by determining that the internal combustion engine is in the automatic stop state by the idling stop control based on the signal from the engine control device. In addition, it is possible to control the heating means controller in a reliable manner in association with the timing at which the internal combustion engine is automatically stopped by the idling stop device.

  Further, according to the control method of the reducing agent supply system of the present invention, the operation of the heating means is stopped when the internal combustion engine is automatically stopped by the idling stop control. Wasteful consumption of energy due to the operation of the heating means in a state where the injection control is not performed can be suppressed.

DESCRIPTION OF EMBODIMENTS Embodiments relating to a control device and a control method for a reducing agent supply system of the present invention will be specifically described below with reference to the drawings. However, this embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In addition, in each figure, what has attached | subjected the same code | symbol has shown the same member, and description is abbreviate | omitted suitably.

1. Exhaust Purification Device First, an example of the configuration of an exhaust purification device provided with the control device of the reducing agent supply system of the present embodiment will be described with reference to FIG.
The exhaust purification device 10 shown in FIG. 1 injects and supplies a urea aqueous solution as a liquid reducing agent to the upstream side of the reduction catalyst 13 disposed in the exhaust passage, and the NO _x contained in the exhaust gas in the reduction catalyst 13. Is an exhaust purification device 10 that selectively reduces and purifies the exhaust gas. The exhaust purification device 10 is disposed in the middle of an exhaust pipe 11 connected to the internal combustion engine 5, and a reduction catalyst 13 for selectively reducing NO _x contained in the exhaust gas, and an upstream of the reduction catalyst 13. The main component is a reducing agent supply system 20 including a reducing agent injection valve 31 for injecting and supplying a reducing agent into the exhaust pipe 11 on the side.

2. Reducing agent supply system The reducing agent supply system 20 provided in the exhaust gas purification apparatus 10 of the present embodiment stores a reducing agent injection valve 31 fixed to the exhaust pipe 11 on the upstream side of the reducing catalyst 13 and a liquid reducing agent. In order to control the storage tank 50, the pump module 40 including the pump 41 that pumps the reducing agent in the storage tank 50 to the reducing agent injection valve 31, and the amount of reducing agent injected into the exhaust pipe 11. In addition, a control device (hereinafter referred to as “DCU: Dosing Control Unit”) 60 for controlling the reducing agent injection valve 31 and the pump 41 is provided. The pump module 40 and the reducing agent injection valve 31 are connected by a first supply passage 58, the storage tank 50 and the pump module 40 are connected by a second supply passage 57, and the pump module 40 and the storage tank. 50 is connected by a circulation passage 59.

In the example of the exhaust emission control device 10 shown in FIG. 1, a control device (hereinafter referred to as “ECU: Engine Control Unit”) 70 for controlling the operating state of the internal combustion engine 5 is connected to the DCU 60. Information regarding the operating state of the internal combustion engine, such as the fuel injection amount, injection timing, and rotation speed of the internal combustion engine 5, is output.
In this embodiment, the ECU 70 and the DCU 60 are configured as separate control devices, but the ECU 70 and the DCU 60 may be configured as a single control device. Further, each signal input / output to / from the DCU 60 may be exchanged via the CAN.

  The storage tank 50 is provided with a temperature sensor 51 for detecting the temperature of the liquid reducing agent stored therein, and a heater 91 for heating the liquid reducing agent. The value detected by the temperature sensor 51 is output as a signal to the DCU 60, and the heater 91 is energized when the temperature of the liquid reducing agent is equal to or lower than a predetermined value. For example, a heating wire can be used as the heater 91, but the heater 91 is not limited to this, and a known one can be used as appropriate.

Further, the pump module 40 is provided with a pump 41, which pumps up the liquid reducing agent in the storage tank 50 through the second supply passage 57 and pumps it to the reducing agent injection valve 31 through the first supply passage 58. It is supposed to be. The pump 41 is composed of an electric gear pump, for example, and can be DUTY controlled by a signal sent from the DCU 60. Further, the first supply passage 58 is provided with a pressure sensor 43, and a value detected by the pressure sensor 43 is output as a signal to the DCU 60, and the pressure value in the first supply passage 58 is maintained at a predetermined value. As a result, the drive DUTY of the pump 41 is controlled. That is, in a state where the pressure in the first supply passage 58 is lower than a predetermined value, the drive DUTY of the pump 41 is controlled to increase, and the pressure in the first supply passage 58 is lower than the predetermined value. In such a state that also rises, the drive DUTY of the pump 41 is controlled to be small.
Note that “pump drive DUTY” means the ratio of pump drive time per cycle in PWM (pulse width modulation) control.

  Further, the first supply passage 58 is provided with a main filter 47 so as to collect foreign substances in the liquid reducing agent pumped to the reducing agent injection valve 31. A circulation passage 59 is branched from the first supply passage 58 between the pump 41 and the main filter 47 and is connected to the storage tank 50. An orifice 45 is provided in the middle of the circulation passage 59, and a pressure control valve 49 is provided closer to the storage tank 50 than the orifice 45. By providing such a circulation passage 59, the pressure value in the first supply passage 58 is predetermined in a state where the liquid reducing agent is pumped by the pump 41 that is feedback-controlled based on the detection value of the pressure sensor 43. When the value is exceeded, the pressure control valve 49 is opened, and a part of the liquid reducing agent is recirculated into the storage tank 50. As the pressure control valve 49, for example, a known check valve or the like can be used.

Further, the pump module 40 is provided with a reverting valve 71, and when the reducing agent supply system 20 does not perform the injection control of the liquid reducing agent, the pump module 40, the reducing agent injection valve 31, and the first supply passage 58 are provided. The liquid reducing agent in the reducing agent supply system including the second supply passage 57 and the like can be recovered in the storage tank 50. Therefore, in a case where the operation of the internal combustion engine 5 is stopped and the control of the reducing agent supply system 20 is not performed under a temperature condition in which the liquid reducing agent is easily frozen, such as in cold weather, the inside of the reducing agent supply system It is possible to prevent the liquid reducing agent from being frozen and to quickly control the injection of the liquid reducing agent when the operation of the internal combustion engine is resumed.
The reverting valve 71 is, for example, an ON-OFF valve that is on / off controlled by a control signal from the DCU 60, and can recover the liquid reducing agent into the storage tank 50 when the valve is opened.

  Further, the reducing agent injection valve 31 can be composed of, for example, an ON-OFF valve that controls ON / OFF of the valve opening by DUTY control. The liquid reducing agent pumped from the pump module 40 to the reducing agent injection valve 31 is maintained at a predetermined pressure, and the reducing agent injection valve 31 is opened by a control signal sent from the DCU 60. Sometimes reducing agent is injected into the exhaust passage.

Each part of the reducing agent supply system of the reducing agent supply system 20 is provided with heaters 92 to 97, respectively. These heaters 92 to 97, when the liquid reducing agent is present in the reducing agent supply system, such as in cold weather, the liquid reducing agent freezes and partially or completely blocks the reducing agent supply system, It is provided to prevent the reducing agent injection control by the reducing agent injection valve 31 from being performed accurately. In addition, energization of these heaters 92 to 97 is controlled by the DCU 60. For example, when it is determined that the liquid reducing agent is in a temperature condition that causes freezing in the reducing agent supply system based on the temperature of the liquid reducing agent or the outside air temperature, a voltage is supplied from the battery. It is supposed to be heated.
These heaters 92 to 97 are not particularly limited, and for example, a heating wire can be used.

3. Internal combustion engine control unit (ECU)
The internal combustion engine 5 provided with the reducing agent supply system 20 to which the present invention is applied is provided with an idling stop function for automatically stopping the internal combustion engine 5. This idling stop function automatically activates the internal combustion engine 5 when a predetermined idling stop condition is satisfied, for example, when the internal combustion engine key switch is turned on and the rotational speed of the internal combustion engine falls below a predetermined value. This is a function to stop and prevent air pollution caused by exhaust gas and noise caused by engine noise.

FIG. 2 shows an example of the configuration of the ECU 70 having a function of performing idling stop control. The ECU 70 is mainly configured by a microcomputer having a known configuration, and a configuration example represented by functional blocks is shown for a portion related to idling stop control.
The ECU 70 in this embodiment includes a switch state detection unit (denoted as “Swt detection”), a rotation speed detection unit (denoted as “Ne detection”), a vehicle speed detection unit (denoted as “vehicle speed detection”), An idling stop control unit (denoted as “Idle-Stop control”) that receives detection results from each unit and automatically stops the internal combustion engine is a major component. Each of these units is specifically realized by executing a program by a microcomputer (not shown).

Among these, the switch state detection unit detects whether the key switch is on or off, and outputs a signal to the idling stop control unit. The rotation speed detection unit detects the rotation speed of the internal combustion engine and outputs a signal to the idling stop control unit. Further, the vehicle speed detection unit estimates the vehicle speed based on the number of rotations of wheels in the vehicle on which the internal combustion engine is mounted, and outputs a signal to the idling stop control unit.
However, the detection method in the rotation speed detection unit and the vehicle speed detection unit is not particularly limited, and may be detected by a method other than the method described above.

  In addition, the idling stop control unit determines whether or not an idling stop condition for automatically stopping the internal combustion engine is satisfied based on the signals sent from the respective units, and the conditions are satisfied. The internal combustion engine is controlled to be stopped. Here, the idling stop condition is, for example, a state where the key switch is in an on state, the rotational speed of the internal combustion engine is equal to or lower than a predetermined threshold, and the vehicle speed is equal to or lower than the predetermined threshold. It can be a case where it continues for a predetermined time or more.

  In the ECU 70 of the present embodiment, the timer count is started when a state where the vehicle is stopped despite the key switch being turned on is detected, and when a predetermined time has passed in the same state, the idling is performed. It is determined that the stop condition is satisfied, and the internal combustion engine is automatically stopped. On the other hand, if the vehicle starts moving or the key switch is turned off before the predetermined time elapses after the timer count is started, the timer is reset and the idling stop control is stopped.

Although not shown, the ECU 70 of the present embodiment once again restarts the internal combustion engine when the idling stop condition is once established and the internal combustion engine is automatically stopped, and then the accelerator lever is stepped on or a predetermined switch is turned on. A return control unit for returning the engine to the operating state is provided.
When the idling stop condition is satisfied and the internal combustion engine is automatically stopped, the ECU 70 outputs to the DCU 60 that the internal combustion engine is stopped by the idling stop function.
However, the idling stop condition can be determined by adding various other elements, and is not limited to the above configuration. For example, it may be determined whether to automatically stop the internal combustion engine by adding a condition that the gear of the transmission is neutral or that the clutch is stepped on if it is a manual transmission vehicle. .

4). Reducing agent supply system control unit (DCU)
FIG. 3 shows a configuration of the DCU 60 for controlling the reducing agent supply system of the present embodiment. Similar to the ECU 70, the DCU 60 is mainly configured by a microcomputer having a known configuration. The DCU 60 is related to operation control of the reducing agent injection valve 31, the pump 41, the reverting valve 71, and the heaters 92 to 97 in FIG. A configuration example represented in functional blocks is shown.
The DCU 60 in this embodiment includes an idling stop determination unit (denoted as “Idle-Stop determination”), a heating means operation determination unit (denoted as “Heater operation determination”), and an energy detection unit (denoted as “Heater power detection”). ), Outside air temperature detection unit (indicated as “Temp detection”), heating means control unit (indicated as “Heater control”), reducing agent injection control unit (indicated as “Uds control”), and reverting valve control Section (noted as “Rtv control”) and the like. Each of these units is specifically realized by executing a program by a microcomputer (not shown).

  The idling stop determination unit determines whether or not the internal combustion engine is automatically stopped by the idling stop control based on a signal sent from the ECU 70. When it is determined that the internal combustion engine is in the automatic stop state, a signal is output to a heating means control unit, a reducing agent injection control unit, and a reverting valve control unit, which will be described later.

The heating means operation determination unit determines whether at least one of the heaters provided in the reducing agent supply system is operating. The energy detection unit is for detecting the magnitude of energy supplied from a power source for operating a heater provided in the reducing agent supply system. The power source is, for example, a battery, and the energy detection unit detects a supply voltage of the battery. The outside air temperature detecting unit is for detecting the outside air temperature based on output information from a temperature sensor that detects the outside air temperature mounted on the vehicle, for example.
The determination results and detection results by these units are sent to the heating means control unit.

  The heating means controller operates the heating means when a predetermined condition is satisfied based on signals sent from the idling stop determination section, the heating means operation determination section, the energy detection section, and the outside air temperature detection section. Is to stop. Specifically, when a signal indicating that the internal combustion engine is in an automatic stop state is sent from the idling stop determination unit, the heater is operating based on the signal sent from the heating means operation determination unit. The basic control is to determine whether the heater is present and to stop the heater when the heater is in operation.

  In the DCU 60 of this embodiment, the heating means control unit is further provided with a timer counter (indicated as “timer 1” in FIG. 3), information on the supply voltage of the battery sent from the energy detection unit, and detection of the outside air temperature. The time until the heater is stopped is changed based on the outside temperature information sent from the section. Specifically, a map that pre-defines the time to stop the heater according to the battery supply voltage and the outside temperature is stored, and if the battery supply voltage is high or the outside temperature is low, the heater is turned off. While it is allowed to lengthen the time until stopping, the heater is quickly stopped when the supply voltage is low or the outside air temperature is high.

For example, under a temperature condition in which the liquid reducing agent is likely to freeze, the time until the heater is stopped is made variable according to the supply voltage of the battery, and is relatively long when the supply voltage is high, and relatively long when the supply voltage is low. Try to keep it short. In this way, it is possible to prevent the liquid reducing agent in the reducing agent supply system from freezing during the automatic stop of the internal combustion engine without significantly reducing the supply voltage of the battery.
On the other hand, under the temperature conditions where the liquid reducing agent is difficult to freeze, it is less necessary to operate the heater, so that the heater is promptly stopped. In this way, wasteful consumption of the battery can be reduced, and there is no risk of freezing of the liquid reducing agent.

  However, it is not essential to make the time to stop the heater operation based on the battery supply voltage, the outside air temperature, etc., both of which can be omitted, and either of them can be considered. Can also be controlled.

Further, the reducing agent injection control unit, in a normal operation state, information on the reducing agent in the storage tank, information on the exhaust gas temperature, the reduction catalyst temperature, the NO _x concentration on the downstream side of the reduction catalyst, and further on the internal combustion engine The injection amount of the reducing agent is controlled based on information on the operating state. On the other hand, when a signal indicating that the internal combustion engine is in the automatic stop state is sent from the idling stop determination unit, since there is no exhaust gas flow, the reducing agent injection valve 31 is closed and the pump 41 is driven. It is supposed to stop.

Further, the reverting valve control unit recovers the liquid reducing agent in the reducing agent supply system into the storage tank when a signal indicating that the internal combustion engine is in the automatic stop state is sent from the idling stop determination unit. In addition, the reverting valve is opened.
In the DCU 60 of the present embodiment, the reverting valve control unit is provided with a timer counter (indicated as “timer 2” in FIG. 3), and the reverting valve is opened after a predetermined time has elapsed after the internal combustion engine is automatically stopped. It is configured as follows. Thus, when the internal combustion engine is automatically stopped by the idling stop control and then returned to the operation mode again in a short time, the liquid reducing agent remains in the reducing agent supply system, and the liquid reducing agent is quickly The injection control can be started.

5. Reducing Agent Injection Control Next, reducing agent injection control performed by the reducing agent supply system 20 provided in the exhaust emission control device 10 of FIG. 1 will be described.
During operation of the internal combustion engine, the liquid reducing agent in the storage tank 50 is pumped up by the pump 41 and pumped to the reducing agent injection valve 31. At this time, the detection value by the pressure sensor 43 provided in the first supply passage 58 on the downstream side of the pump 41 is fed back and controlled to show a predetermined pressure value. For example, when the detected value is less than a predetermined value, the output of the pump 41 is increased. On the other hand, when the pressure value exceeds the predetermined value, the output of the pump 41 is decreased and the liquid reducing agent is stored via the pressure control valve 49. It is returned to the tank 50 and depressurized. As a result, the pressure of the reducing agent pumped toward the reducing agent injection valve 31 is maintained at a substantially constant value.

Further, the reducing agent pumped from the pump module 40 to the reducing agent injection valve 31 is maintained at a substantially constant pressure value, and is injected into the exhaust passage when the reducing agent injection valve 31 is opened. ing. The DCU 60 is based on information such as the operating state of the internal combustion engine, the exhaust temperature, the temperature of the reduction catalyst 13, and the amount of NO _x that has passed through the reduction catalyst 13 without being reduced, measured on the downstream side of the reduction catalyst 13. The amount of reducing agent to be injected is determined, and a control signal corresponding to the amount is generated and output to the reducing agent injection valve 31. The reducing agent injection valve 31 is subjected to DUTY control by this control signal, and an appropriate amount of reducing agent is injected and supplied into the exhaust passage. The reducing agent injected into the exhaust passage flows into the reduction catalyst 13 and is used for the reduction reaction of NO _x contained in the exhaust gas.

6). Control in Internal Stop State of Internal Combustion Engine Next, in the controller (DCU) 60 of the reducing agent supply system of the present embodiment shown in FIG. 3, the reducing agent supply performed when the idling stop condition is satisfied and the engine is automatically stopped. An example of a control method routine of the system 20 will be described with reference to the control flows shown in FIGS.

  First, as shown in FIG. 4, in step S11 after the start, it is determined whether or not the internal combustion engine is automatically stopped by the idling stop control, that is, whether or not it is in the idling stop mode. When the idling stop condition is satisfied and the internal combustion engine is automatically stopped, the DCU 60 of this embodiment is configured to receive a signal from the ECU 70. In step S11, the DCU 60 makes a determination based on this signal. Is called.

Here, FIG. 6 shows an example of the flow of the automatic stop control of the internal combustion engine performed by the ECU 70 when the idling stop condition is satisfied.
In this example, first, in step S1, it is determined whether or not the key switch of the internal combustion engine is turned on. If the key switch is turned on, the process proceeds to step S2.
In step S2, the rotational speed Ne of the internal combustion engine is detected, and it is determined whether or not the rotational speed Ne is equal to or less than a predetermined reference value Ne0. If the rotational speed Ne is equal to or less than the reference value Ne, the process proceeds to step S3. The reference value Ne0 is set to a value that can be determined to be an idling state.

  Next, in step S3, the speed of the vehicle is detected, and it is determined whether or not the vehicle speed is equal to or less than a predetermined reference value S0. If the vehicle speed is less than or equal to the reference value S0, the process proceeds to step S4. The reference value S0 is generally set to 0 km / hr so that it can be determined that the vehicle is stopped.

If any of the conditions up to step S1 to step S3 is not satisfied, the idling stop control is terminated, while in step S4, where all the conditions from step S1 to step S3 are satisfied, the timer is advanced. Actuate.
Next, in step S5 to step S6, the key switch is turned on and the rotational speed Ne of the internal combustion engine becomes equal to or less than the reference value Ne0 after the timer is activated until the reference time T0 elapses. Is determined. If the key switch is turned off before the reference time T0 elapses or the rotational speed Ne of the internal combustion engine exceeds the reference value Ne0, the idling stop control is terminated.

On the other hand, when the key switch is turned on and the reference time T0 has passed with the engine speed Ne remaining below the reference value, the process proceeds to step S7, and the idling stop control is terminated by stopping the engine. .
Thereafter, although not shown, a signal indicating that the internal combustion engine is automatically stopped by the idling stop control is output to the DCU.
When the DCU directly determines whether or not the idling stop condition is satisfied, step S11 in the control flow in FIG. 4 is replaced with steps S1 to S7 in the control flow in FIG. be able to.

  Returning to FIG. 4, if it is determined in step S11 that the internal combustion engine is in the automatic stop state, the process proceeds to step S12, and is any of the heaters 92 to 97 provided in the reducing agent supply system operating? It is determined whether or not. If all of the heaters 92 to 97 are not operating, the process proceeds to step S20 in FIG. 5, while if any heater is operating, the process proceeds to step S13.

Next, in step S13, the value of the supply voltage of the battery that supplies voltage to the heater and the outside air temperature are detected. In step S14, the heater is stopped based on the supply voltage and the outside air temperature of the battery. Timer 1 value Ta0 which is the time until is calculated.
For example, a map that predefines the time until the heater is stopped according to the supply voltage of the battery and the outside air temperature can be stored and read. Under a temperature condition where the liquid reducing agent is likely to freeze, the liquid reducing agent is made relatively long when the supply voltage is high and relatively short when the supply voltage is low, depending on the supply voltage of the battery. On the other hand, under the temperature conditions where the liquid reducing agent is difficult to freeze, it is less necessary to operate the heater, so that the heater is promptly stopped.

  When the timer 1 value Ta0 is determined in step S14, the timer 1 is activated in step S15 to start counting. Next, in step S16 to step S17, it is determined whether or not the rotational speed Ne of the internal combustion engine is equal to or less than the reference value Ne0 after the timer 1 is activated until the timer 1 value Ta0 elapses. When the rotational speed Ne of the internal combustion engine exceeds the reference value Ne0 before the timer 1 value Ta0 elapses, the internal combustion engine returns to the operating state again, and the injection control of the liquid reducing agent is resumed. In step S19, the timer 1 is reset to end the operation of the heater and the process ends.

On the other hand, if the timer Ne value Ta0 has elapsed while the rotational speed Ne of the internal combustion engine remains below the reference value Ne0, the process proceeds to step S18, the heater is de-energized, the heater operation is stopped, and then the process proceeds to step S20. move on. When the internal combustion engine is stopped by the idling stop control, there is no flow of exhaust gas, and the liquid reductant injection control is not performed, so that the heater is operated when a predetermined time has elapsed in the idling stop state. By stopping, it is possible to prevent the battery from being wasted due to the heater continuously operating.
In step S16, whether or not the internal combustion engine returns to the operating state is determined again based on the rotational speed Ne of the internal combustion engine. However, based on another condition such as whether or not the accelerator is depressed. You may make it determine.

After the operation of the heater is stopped, recovery control of the liquid reducing agent remaining in the reducing agent supply system is performed after step S20.
First, the timer 2 is operated in step S20. Next, in step S21 to step S22, it is determined whether or not the rotational speed Ne of the internal combustion engine is equal to or less than a reference value Ne0 after the timer 2 is actuated until the timer 2 value Tb0 elapses. If the rotational speed Ne of the internal combustion engine exceeds the reference value Ne0 before the timer 2 value Tb0 elapses, the internal combustion engine returns to the operating state again, and the injection control of the liquid reducing agent is resumed. Proceeding to step S24, the recovery of the liquid reducing agent in the reducing agent supply system is not performed, and the timer 2 is reset and terminated.

On the other hand, if the timer Ne value Tb0 has elapsed with the rotational speed Ne of the internal combustion engine kept below the reference value Ne0, the process proceeds to step S23, where the pump 41 is stopped while the reverting valve 71 is driven, thereby reducing The liquid reducing agent remaining in the agent supply system is collected in the storage tank 50. As a result, when the internal combustion engine is stopped by the idling stop control, the heater operation is stopped and the liquid reducing agent is recovered to prevent the battery from being wasted. Freezing and crystallization can be prevented.
In addition, although the operation of the heater is stopped in the previous step S18, the time from the stop of the heater operation to the recovery of the liquid reducing agent is short, so that the liquid reducing agent is not likely to freeze during this time. It has become.

7. Another Configuration Example The control flow described so far is an example of an embodiment, and some steps can be omitted or the order can be changed.
For example, when performing the recovery control of the liquid reducing agent, when the liquid reducing agent is always recovered when the heater is stopped, the above-described steps S20 to S22 may be omitted. .
Further, when the reducing agent recovery control in steps S20 to S24 and the heater stop control in steps S12 to S19 are performed in a reversed order, the heater operation is stopped after the liquid reducing agent is recovered. Therefore, freezing of the liquid reducing agent is surely prevented.

  In the present embodiment, the reducing agent supply system in which liquid reducing agent pumped by the pump is directly injected into the exhaust pipe by the reducing agent injection valve is described as an example. In addition to this, it is applied to an air-assisted reducing agent supply system that supplies the mixing chamber through a valve that adjusts the flow rate of the reducing agent pumped by the pump and supplies it into the exhaust pipe while atomizing with high-pressure air. You can also.

It is a figure which shows the structural example of an exhaust gas purification apparatus. It is a block diagram which shows the structural example of the part of the idling stop control of the engine control apparatus (ECU) with which the exhaust gas purification device was equipped. It is a block diagram which shows the structural example of the reducing agent supply system control apparatus (DCU) with which the exhaust gas purification apparatus was equipped. It is a flowchart which shows an example of the method of stopping the action | operation of a heating means. It is a flowchart which shows an example of the method of collect | recovering liquid reducing agents to a storage tank. It is a flowchart which shows an example of idling stop control.

Explanation of symbols

10: exhaust purification device, 11: exhaust passage, 13: reduction catalyst, 15 · 16: temperature sensor, 17: NO _X sensor, 20: reducing agent supply system, 31: reducing agent injection valve, 40: pump module, 41: Pump: 43: Pressure sensor, 45: Orifice, 47: Main filter, 49: Pressure control valve, 50: Storage tank, 51: Temperature sensor, 57: Second supply passage, 58: First supply passage, 59: Circulation path, 60: Reducing agent supply system control unit (DCU), 70: Engine control unit (ECU), 71: Reverting valve, 91, 92, 93, 94, 95, 96, 97: Heater

Claims (9)

The liquid reducing agent is used in an exhaust purification device that injects and supplies a liquid reducing agent to an exhaust upstream side of a reduction catalyst disposed in an exhaust passage of an internal combustion engine, and reduces and purifies nitrogen oxides in the exhaust with the reduction catalyst. , A pump for pumping the liquid reducing agent in the storage tank, a reducing agent injection valve for controlling a supply amount of the liquid reducing agent pumped by the pump, and the liquid reduction A controller for controlling a reducing agent supply system including a reducing agent supply passage through which the agent passes;
An idling stop determination unit that determines whether or not the internal combustion engine is stopped by idling stop control that automatically stops the internal combustion engine;
A heating means operation determination unit that determines whether or not a heating means provided in a reducing agent supply system that supplies the liquid reducing agent to the reducing agent injection valve is operating;
A heating means control section for stopping the operation of the heating means when the internal combustion engine is in an automatic stop state and the heating means is operating;
A control device for a reducing agent supply system.   2. The reducing agent supply system according to claim 1, wherein the heating unit control unit stops the operation of the heating unit after a predetermined time elapses after it is determined that the internal combustion engine is in an automatic stop state. Control device.   An outside air temperature detection unit that detects outside air temperature information is provided, and the heating unit control unit determines a time from when it is determined that the internal combustion engine is in an automatic stop state until the heating unit is stopped according to the outside air temperature. The control device for a reducing agent supply system according to claim 1, wherein the controller is changed.   An energy detection unit that detects the magnitude of energy supplied from a power source of the heating unit is provided, and the heating unit control unit stops the heating unit after it is determined that the internal combustion engine is in an automatic stop state. The control device of the reducing agent supply system according to any one of claims 1 to 3, wherein the time until the time is changed according to the magnitude of the energy.   5. The reductant return control unit that recovers the liquid reductant of the reductant supply system in the storage tank when the internal combustion engine is in an automatic stop state. A control device for a reducing agent supply system according to claim 1.   6. The reducing agent supply system according to claim 5, wherein the reducing agent return control unit recovers the liquid reducing agent after a predetermined time has elapsed after it is determined that the internal combustion engine is in an automatic stop state. Control device.   The idling stop determination unit is in an automatic stop state when at least a key switch of the internal combustion engine is on and a state where the rotational speed of the internal combustion engine is equal to or lower than a predetermined value continues for a predetermined time. The controller for a reducing agent supply system according to any one of claims 1 to 6, wherein the controller is determined to be in the control system.   The idling stop determination unit determines whether or not the internal combustion engine is in an automatic stop state based on a signal from an engine control device that performs operation control of the internal combustion engine. The control apparatus of the reducing agent supply system as described in any one of Claims. The liquid reduction agent is used in an exhaust purification device that injects and supplies a liquid reducing agent to the exhaust upstream side of a reduction catalyst disposed in an exhaust passage of an internal combustion engine, and reduces and purifies nitrogen oxides in the exhaust with the reduction catalyst. A storage tank in which an agent is stored, a pump for pumping the liquid reducing agent in the storage tank, a reducing agent injection valve for controlling the supply of the liquid reducing agent pumped by the pump, and the liquid reduction In a control method of a reducing agent supply system comprising a reducing agent supply passage through which an agent flows,
It is determined whether or not the heating means provided in the reducing agent supply system is operating while the internal combustion engine is stopped by idling stop control for automatically stopping the internal combustion engine, and the heating means is operated. A control method for a reducing agent supply system, characterized in that the operation of the heating means is stopped when it is in the middle.

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