JP2009197710A - Device for verifying actual injection amount of additive, abnormality determination device of additive feeder, and injection control device of additive feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for verifying actual injection amount of an additive feeder capable of calculating the actual injection amount of the additive with excellent accuracy, and an abnormality determination device of the additive feeder and an injection control device of the additive feeder based on the actual injection amount of the additive calculated with excellent accuracy. <P>SOLUTION: The control device of the additive feeder has an actual injection amount computation unit which computes the actual injection amount of the additive actually injected from an additive injection valve within the predetermined period based on the balance of the energy received or emitted by an additive feeding system of the additive feeder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an additive actual injection amount verification device of an additive supply device provided in an exhaust purification device, an abnormality determination device of the additive supply device, and an injection control device of the additive supply device. In particular, the additive actual injection amount verification device of the additive supply device that calculates the additive amount necessary for the reduction of NO _x contained in the exhaust gas and performs injection control of the additive, the abnormality determination device of the additive supply device And an injection control device of the additive supply device.

Conventionally, in exhaust gas discharged from the internal combustion engine such as a diesel engine, the nitrogen oxides that may affect the environment (hereinafter, referred to as NO _X) are included. As an exhaust purification device used to purify this NO _x , an additive such as a urea solution is injected and supplied upstream of the reduction catalyst disposed in the exhaust passage, and NO _x in the exhaust is selected in the reduction catalyst An exhaust purification device (SCR system) that performs reduction and purification is known.

As an aspect of such an exhaust purification device, the additive is pumped toward the additive injection valve fixed to the exhaust pipe so that the injection hole is desired in the exhaust pipe, and the additive is based on the addition instruction value obtained by calculation. There is an exhaust purification device of a type in which an additive is injected and supplied into an exhaust pipe by controlling opening and closing of an injection valve. In the additive supply device used in such an exhaust purification device, the additive supply path and additive injection valve may be clogged, or each part of the additive supply device may deteriorate over time. There may be an error between the indicated value and the actual injection amount. If the actual injection amount of the additive is insufficient, the non-reduced NO _x is released into the atmosphere as it is, while if the actual injection amount of the additive becomes excessive, the additive components that have not been used in the reduction reaction become catalyst. Can cause environmental degradation. Therefore, it is desired to accurately obtain the actual injection amount of the additive injected from the additive supply device, detect abnormality of the additive supply device, or correct the injection amount.

Various methods have been proposed as a method for obtaining the actual injection amount from the additive supply device.
For example, a method is disclosed in which the actual amount of additive is measured by a flow meter installed in the additive flow path. More specifically, the reducing agent addition controller calculates the target addition amount of the reducing agent according to the operating condition of the engine, and calculates the target addition amount of the reducing agent from the actual addition amount of the reducing agent actually added to the exhaust gas. The engine exhaust purification device calculates the estimated amount of adsorption of the reducing agent adsorbed on the nitrogen oxide reduction catalyst by sequentially integrating the difference obtained by subtracting (see Patent Document 1).

  In addition, although it is an example of a system that uses unburned fuel (HC) as an additive, a method for obtaining an estimated additive amount by periodically integrating the additive additive amount equivalent value that appears in the air-fuel ratio of the exhaust system is disclosed. ing. More specifically, when an additive is added from the addition valve into the exhaust port, the air-fuel ratio detected by the air-fuel ratio sensor is lower than the air-fuel ratio due to the fuel injected from the fuel injection valve into the combustion chamber. The estimated additive amount is obtained by periodically integrating the additive additive equivalent value that appears in the air-fuel ratio change, and the estimated additive amount is compared with the judgment value to accurately add the error. This is an additive addition error detection method for detecting abnormality and determining normality (see Patent Document 2).

  Furthermore, a method is disclosed in which the actual injection amount is estimated based on a liquid level measured by a liquid level meter disposed in the additive storage tank. More specifically, the liquid level L0 in the reducing agent tank when the key switch of the engine is turned on is measured, the travel distance D1 after the key switch is turned on is measured from the travel distance integrating meter, and the travel distance D1 is predetermined. It is determined whether or not the travel distance D0 or more has been reached, and the liquid level L1 in the reducing agent tank when the travel distance D0 or more is reached is confirmed and measured from the amount of change in the liquid level (L0-L1). It is determined whether or not the urea solution consumption ΔL to be performed is within a predetermined range (Lmin ≦ ΔL ≦ Lmax). It is a reducing agent injection condition determination device of an exhaust purification system (patent document 3).

JP 2004-293489 A (Claims Fig. 1) JP-A-2005-54723 (Claims Fig. 1) Japanese Patent Laying-Open No. 2006-250117 (Claims Fig. 1)

  However, in the method for calculating the actual amount of additive using a flow meter as described in Patent Document 1, it is necessary to additionally provide a flow meter, leading to an increase in cost and relatively high measurement accuracy. The calculation accuracy is constrained by a low flow meter, and the calculation accuracy may be reduced. In addition, depending on the flow meter, even a two-layer fluid in which an additive and air are mixed is not distinguished, and air may be detected as a liquid and calculation accuracy may be reduced.

Further, when an NO _X sensor is used in an additive supply device for urea solution by applying an actual injection amount calculation method using a sensor as described in Patent Document 2, the NO _X sensor is NO _X Since it has the characteristic of detecting not only ammonia but also ammonia concentration alone cannot be distinguished, and it is difficult to use the detected value for calculating the injection amount of the urea solution.

  Further, the consumption calculation method using the liquid level in the tank as described in Patent Document 3 cannot determine a measurement error or the like due to the inclination of the vehicle, and the current general liquid level. The sensor has a problem that the accuracy of the calculation result is low.

  Accordingly, the inventors of the present invention diligently worked and provided such an actual injection amount calculation unit that calculates the actual injection amount of the additive based on the energy balance in the supply system of the additive supply device. And the present invention has been completed. That is, the object of the present invention is based on the actual injection amount verification device of the additive supply device capable of accurately calculating the actual injection amount of the additive, and the actual injection amount of the additive calculated accurately. An abnormality determination device for an additive supply device and an injection control device for the additive supply device are provided.

  According to the present invention, an additive is supplied to the exhaust upstream side of a reduction catalyst disposed in an exhaust passage of an internal combustion engine, and is provided in an exhaust purification device that reduces and purifies nitrogen oxides in exhaust gas with a reduction catalyst. An electric pump that pumps the agent, an additive injection valve that performs injection control of the additive pumped from the electric pump, an additive supply passage disposed between the electric pump and the additive injection valve, An additive actual injection amount verification device for verifying an injection amount of an additive in an additive supply device comprising: an additive supply system of the additive supply device receiving or releasing within a predetermined period And an actual injection amount calculation unit for calculating an actual injection amount of the additive actually injected from the additive injection valve within a predetermined period based on the energy balance. A verification device is provided to solve the above-mentioned problems Rukoto can.

  Further, in configuring the actual injection amount verification device of the additive supply device of the present invention, the actual injection amount calculation unit includes at least the amount of power supplied to the electric pump and the additive supply system within a predetermined period. It is preferable to calculate the actual injection amount of the additive based on the information on the increase / decrease amount of the heat amount and the increase / decrease amount of the pressure in the additive supply passage.

  Further, in configuring the actual injection amount verification device of the additive supply device of the present invention, the calculation of the actual injection amount may be executed when heating control or cooling control of the additive supply system is not performed. preferable.

  Another aspect of the present invention provides an exhaust purification apparatus that supplies an additive 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. An electric pump that pumps the additive, an additive injection valve that performs injection control of the additive pumped from the electric pump, and an additive disposed between the electric pump and the additive injection valve An abnormality diagnosis device for an additive supply device comprising a supply passage, a required addition amount calculation unit for calculating a required addition amount of the additive to be supplied to the exhaust passage, and an additive supply within a predetermined period The actual injection amount that calculates the actual injection amount of the additive actually injected from the additive injection valve within a predetermined period based on the energy balance received or released by the additive supply system in the device Compare the calculation unit with the required addition amount and the actual injection amount. An abnormality determination device of the additive supply apparatus characterized by comprising, an abnormality determination unit that performs an abnormality diagnosis of the additive supply device by.

  Still another aspect of the present invention provides an exhaust purification device that supplies an additive 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. An electric pump that pumps the additive, an additive injection valve that controls the injection of the additive pumped from the electric pump, and an additive disposed between the electric pump and the additive injection valve An additive supply device comprising: an additive supply passage; a required addition amount calculation unit for calculating a required addition amount of the additive to be supplied to the exhaust passage; and an additive supply within a predetermined period The actual injection amount that calculates the actual injection amount of the additive actually injected from the additive injection valve within a predetermined period based on the energy balance received or released by the additive supply system in the device Compare the calculation unit with the required addition amount and the actual injection amount, A control device for the additive supply device, characterized in that it comprises the addition instruction value correction section for correcting the added instruction value which is the basis of the control signal based on the additive injection valve, the results.

  According to the actual injection amount verification device of the additive supply apparatus of the present invention, since the actual injection amount calculation unit that calculates the actual injection amount according to the law of conservation of energy is provided, the additive such as the heat transfer coefficient is included. The actual injection amount can be accurately calculated in consideration of physical properties. Therefore, the calculation result of the actual injection amount can be used for abnormality determination by comparison with the required addition amount of the additive and the correction of the addition instruction value, which can contribute to improving the accuracy of additive injection control.

  Moreover, according to the abnormality determination device for the additive supply device of the present invention, the actual injection amount calculation unit that calculates the actual injection amount according to the law of energy conservation, and the calculated actual injection amount and the required addition amount are compared. Since the abnormality determining unit is provided, it is possible to accurately determine the abnormality of the additive supply device based on the calculation result of the actual injection amount with relatively high accuracy. Therefore, the reliability of the abnormality determination result is improved, and the additive supply device can be repaired and repaired promptly.

  Further, according to the injection control device of the additive supply device of the present invention, the actual injection amount calculation unit that calculates the actual injection amount according to the law of conservation of energy, and the error between the calculated actual injection amount and the required injection amount. Since the addition instruction value correction unit for correcting the addition instruction value is provided, the injection amount correction control can be performed with high accuracy based on the calculation result of the actual injection amount with relatively high accuracy. . Therefore, even when an abnormality is found in the additive supply device, the additive addition instruction value can be corrected and the amount of additive required for exhaust purification can be accurately supplied by injection.

DESCRIPTION OF EMBODIMENTS Embodiments relating to an additive actual injection amount verification apparatus, an additive supply apparatus abnormality determination apparatus, and an additive supply apparatus injection control apparatus according to 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 gas purification apparatus First, an example of the configuration of an exhaust gas purification apparatus provided with the DCU of this embodiment is shown in FIG.
The exhaust gas purification apparatus 10 shown in FIG. 1 injects and supplies a urea solution as an additive to the upstream side of the reduction catalyst 13 disposed in the exhaust passage, and selects NO _X contained in the exhaust gas in the reduction catalyst 13. This is an exhaust emission control device 10 that performs reduction purification. 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, and an upstream side of the reduction catalyst 13. The main component is an additive supply device 20 for injecting and supplying the urea solution into the exhaust pipe 11.

2. Additive Supply Device The additive supply device 20 provided in the exhaust purification device 10 of the present embodiment stores an additive injection valve 31 fixed to the exhaust pipe 11 on the upstream side of the reduction catalyst 13 and a urea solution. A pump module 40 including a storage tank 50, an electric pump (hereinafter sometimes simply referred to as “pump”) 41 that pumps the urea solution in the storage tank 50 to the additive injection valve 31, and an exhaust pipe In order to control the injection amount of the additive to be injected and supplied into the interior 11, a control device 60 (hereinafter referred to as “DCU: Dosing Control Unit”) 60 that controls the operation of the additive injection valve 31 and the electric pump 41 is provided. I have. The pump module 40 and the additive 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 are further connected. 50 is connected by a reflux passage 59.

In the example of the exhaust purification device 10 shown in FIG. 1, the DCU 60 is connected to the CAN 65. The CAN 65 is connected to a control unit 70 (hereinafter also referred to as “ECU: Engine Control Unit”) 70 for controlling the operating state of the internal combustion engine. The fuel injection amount, the injection timing, and the rotational speed are connected. In addition to information on the operating state of the internal combustion engine including the above, information on all sensors provided in the exhaust purification device 10 is also written. The CAN 65 can determine whether or not the input signal value is within the standard range of the CAN 65. The DCU 60 connected to the CAN 65 can read information on the CAN 65 and output information on the CAN 65.
In this embodiment, the ECU 70 and the DCU 60 are composed of separate control units, and information can be exchanged via the CAN 65. However, the ECU 70 and the DCU 60 are configured as one control unit. In addition, CAN can be omitted.

As the additive injection valve 31, for example, an ON-OFF valve whose ON / OFF is controlled by duty control can be used. The urea solution pumped from the pump module 40 to the additive injection valve 31 is maintained at a predetermined pressure, and the additive injection valve 31 is opened by energization control by the operation device 67 of the additive injection valve. Sometimes urea solution is injected into the exhaust passage.
The additive injection valve operating device 67 sets the duty ratio and energization time of the pulse voltage to be applied to the additive injection valve 31 based on the additive addition instruction value transmitted from the DCU 60, and the additive injection valve. 31 energization control is performed.

  A temperature sensor for detecting the temperature of the urea solution flowing into the additive injection valve 31 is provided at the inlet of the additive injection valve 31 in the first supply passage 58 connected to the additive injection valve 31. 33 is provided. The temperature information detected by the temperature sensor 33 is sent to the DCU 60.

In addition, the pump module 40 is provided with an electric pump 41, which pumps up the urea solution in the storage tank 50 through the second supply passage 57 and supplies the additive injection valve 31 through the first supply passage 58. It is designed to pump. The electric pump 41 includes, for example, a diaphragm pump or a gear pump, and energization control is performed 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. Thus, the drive duty of the electric 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 electric pump 41 is controlled to be large, and the pressure in the first supply passage 58 is predetermined. In a state where the value rises above the value, the drive duty of the electric pump 41 is controlled to be small.
The “drive duty of the electric pump” means the ratio of the drive time of the electric pump per cycle in PWM (pulse width modulation) control.

The first supply passage 58 is provided with a main filter 47 so as to collect foreign substances in the urea solution pumped to the additive injection valve 31. A reflux passage 59 is branched from the first supply passage 58 between the electric pump 41 and the main filter 47 and is connected to the storage tank 50. A pressure control valve 49 is provided in the middle of the reflux passage 59. By providing such a reflux passage 59, the pressure value in the first supply passage 58 can be increased in a state where the urea solution is pumped by the electric pump 41 that is feedback-controlled based on the detection value of the pressure sensor 43. When the predetermined value is exceeded, the pressure control valve 49 is opened, and a part of the urea solution 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.
In the example of the present embodiment, an orifice may be provided instead of the pressure control valve 49 provided in the middle of the reflux passage 59.

Further, the pump module 40 is provided with a reverting valve 71, and when the additive supply apparatus 20 does not perform the urea solution injection control, the pump module 40, the additive injection valve 31, the first supply passage 58, The urea solution of the additive supply system including the second supply passage 57 and the like can be collected in the storage tank 50. Therefore, when the internal combustion engine 5 is stopped and the additive supply device 20 is not controlled under a temperature condition in which the urea solution is likely to freeze, such as during cold weather, the urea solution in the additive supply system When freezing is prevented and then the operation of the internal combustion engine is resumed, there is no injection failure due to clogging.
For example, the reverting valve 71 has a function of switching the flow path of the urea solution in the forward direction from the storage tank 50 to the additive injection valve 31 or in the reverse direction from the additive injection valve 31 to the storage tank 50. When the ignition switch of the internal combustion engine is turned off, the urea solution can be recovered in the storage tank 50 by switching the flow path in the reverse direction and driving the pump 41.

Each part of the additive supply system of the additive supply apparatus 20 is provided with heaters 92 to 97, respectively. When the urea solution is present in the additive supply system in a cold or cold environment, these heaters 92 to 97 freeze the urea solution partially or completely to block the additive supply system. It is provided to prevent the additive injection control by the 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 urea solution is in a temperature condition that causes the urea solution to freeze in the additive supply system based on the temperature of the urea solution, the outside air temperature, etc., voltage is supplied from the battery and heated. It has become so.
These heaters 92 to 97 are not particularly limited, and for example, a heating wire can be used.

  Note that the calculation of the actual injection amount of the additive, which will be described later, is preferably performed with the heater turned off. In the state where the heater is turned on, it is necessary to take into account the increase in the amount of heat with respect to the electric pump 41 and the first supply passage 58. Since the heat balance model by this heater is complicated, the accuracy of the calculation result is reduced. It is because there is a possibility of doing.

3. Additive Injection Control Next, additive injection control performed by the additive supply device 20 provided in the exhaust purification device 10 of FIG. 1 will be described.
During operation of the internal combustion engine 5, the additive in the storage tank 50 is pumped up by the electric pump 41 and is pumped toward the additive injection valve 31. At this time, feedback detection of the electric pump 41 is performed so that the detection value by the pressure sensor 43 provided in the first supply passage 58 on the downstream side of the electric pump 41 is fed back and maintained at a predetermined pressure value. Is called. For example, when the detected value is less than the set value, the output of the electric pump 41 is increased to increase the pressure, while when the pressure value exceeds the set value, the output of the electric pump 41 is decreased and the pressure control valve 49 is turned on. The additive is refluxed to the storage tank 50 and depressurized. Thereby, the pressure of the additive pumped to the additive injection valve 31 side is maintained at a substantially constant value.

The additive maintained at a predetermined pressure value in the first supply passage 58 is injected into the exhaust passage when the additive injection valve 31 is opened. The opening / closing control of the additive injection valve 31 is performed by energization control by the operation device 67 of the additive injection valve based on the addition instruction value from the DCU 60.
The DCU 60 also has information such as the operating state of the internal combustion engine 5, 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 required injection amount of the additive to be supplied to is calculated. Normally, this required injection amount is sent as it is to the operation device 67 of the additive injection valve as an addition instruction value. Then, the additive injection valve operating device 67 performs energization control of the additive injection valve 31 according to the addition instruction value, duty control of the additive injection valve 31 is performed, and the additive is injected into the exhaust passage. Is done. The additive injected into the exhaust passage flows into the reduction catalyst 13 together with the exhaust gas, and is used for the reduction reaction of NO _x contained in the exhaust gas.

4). Additive supply unit control unit (DCU)
FIG. 2 shows a portion of the DCU 60 for controlling the additive supply device of the present embodiment that performs verification of the actual additive injection amount, abnormality determination of the additive supply device, and injection amount correction control of the additive supply device. A configuration example represented in functional blocks is shown.
The DCU 60 of the present embodiment includes a CAN information extraction / generation unit (indicated as “CAN information extraction / generation” in FIG. 2), a pump supply power calculation unit (indicated as “Epump calculation” in FIG. 2), and an additive return. A flow rate calculation unit (indicated as “recirculation amount calculation” in FIG. 2), an injection valve heat dissipation amount calculation unit (indicated as “Hinj calculation” in FIG. 2), and a passage heat dissipation amount calculation unit (in FIG. 2, “Hpipe calculation”). ”, A pump heat release amount calculation unit (indicated as“ Hpump calculation ”in FIG. 2), a required injection amount calculation unit (indicated as“ required injection amount calculation ”in FIG. 2), and an actual injection amount calculation 2 (denoted as “actual injection amount calculation” in FIG. 2), an abnormality determination unit (denoted as “abnormality determination” in FIG. 2) of the additive supply device, and an addition instruction value correction unit (“addition instruction value in FIG. 2)” Etc.) as main components. Specifically, these are realized by execution of a program by a microcomputer (not shown).

  Among these, the CAN information extraction and generation unit is a part that receives sensor information, operation information of the internal combustion engine, and the like existing on the CAN 65 and transmits them to other parts of the DCU 60. In the example of the DCU 60 provided in the exhaust emission control device of the present embodiment, at least the signal Tenv from the outside air temperature sensor provided in the vehicle, the signal Ttank from the temperature sensor provided in the storage tank, and the first supply passage A signal Psens from the pressure sensor provided and a signal Patm from the atmospheric pressure sensor are received and transmitted to other parts.

  The pump supply power calculation unit is a part that calculates the amount of power Epump supplied from the battery to the electric pump when performing feedback control of the electric pump. For example, the electric energy Epump supplied within a predetermined time is calculated based on the current value Apump sent to the electric pump and the battery voltage Vb.

  The additive reflux amount calculation unit is a part that detects the total amount (Qbf) of the additive that is returned from the first supply passage to the storage tank via the reflux passage. For example, the relationship between the pressure in the first supply passage and the reflux amount of the additive returned to the storage tank is obtained in advance, and the reflux amount of the additive according to the pressure in the first supply passage is integrated. The total amount of additive (Qbf) returned to the storage tank can be calculated.

  Further, the injection valve heat release amount calculation unit is a portion for calculating the amount of heat Hdos radiated from the additive injection valve by calculation. For example, after calculating the resistance value of the electromagnetic solenoid of the additive injection valve, which is estimated based on the current value Ados energized to the additive injection valve or a physical model, the relationship between the resistance value and temperature The temperature Tdos of the additive injection valve is obtained based on the physical properties of the solenoid material indicating After subtracting the sensor value Tenv of the outside air temperature sensor from the temperature Tdos of the additive injection valve and multiplying by the surface area εdos of the additive injection valve, the additive is further multiplied by the heat transfer coefficient hdos of the additive injection valve. The amount of heat Hdos radiated from the injection valve is calculated.

  The passage heat dissipation amount calculation unit is a portion that calculates the amount of heat Hpump radiated from the first supply passage by calculation. For example, assuming that the temperature of the additive in the first supply passage matches the temperature of the additive in the storage tank, the temperature outside the first supply passage matches the sensor value of the outside air temperature sensor Assuming that the sensor value Tenv of the outside air temperature sensor is subtracted from the sensor value Ttank of the temperature sensor, the surface area εpipe of the first supply passage is multiplied, and then the heat transfer coefficient hpipe of the first supply passage is multiplied. Thus, the amount of heat Hpipe radiated from the first supply passage is calculated.

The pump heat dissipation amount calculation unit is a portion for calculating the amount of heat Hpump radiated from the pump by calculation. For example, after subtracting the sensor value Tenv of the outside air temperature sensor from the pump temperature Tpump estimated based on the current value Apump energized to the pump, and multiplying by the pump surface area εpump, the heat of the pump By multiplying the transfer coefficient hpump, the amount of heat Hpump radiated from the pump is calculated.
However, if the pump and the motor that drives the pump are thermally insulated, the amount of heat released from the pump can be ignored, and therefore the pump heat dissipation amount calculation unit may not be provided.

Further, the required injection amount calculation unit is connected to the operating state such as the rotational speed of the internal combustion engine, the fuel injection amount, the fuel injection timing, the exhaust temperature, the temperature of the reduction catalyst, and the downstream side of the reduction catalyst via the CAN information extraction and generation unit. receives information such as of the NO _X concentration is a portion for calculating the volume of additive needed to reduce and purify NO _X in the exhaust gas. The calculated required injection amount is directly sent to the operation device for the additive injection valve as an addition instruction value.

Further, the actual injection amount calculation unit is configured to pass the additive injection valve based on the supply energy supplied to the additive supply device and the release energy released from the additive supply device within a predetermined time. The volume of the additive actually injected into the exhaust passage is calculated. That is, the actual injection quantity calculating unit is different from the additive added instruction value as an additive amount required to reduce and purify NO _X in the exhaust gas, the actual injection quantity actually injected into the exhaust pipe Are provided for computing.
In the actual injection amount calculation unit of the DCU 60 provided in the exhaust purification apparatus of the present embodiment, the actual injection amount Qdos of the additive is calculated using the following formula (1).

Qdos = {Epump− (Pad × Qbf + Hdos + Hpipe + Hpump)} / Pad (1)
Qdos: Actual injection volume (ml)
Epump: Power supplied to the pump (W)
Pad: Additive relative pressure (Pa)
Qbf: Additive reflux amount (ml)
Hdos: Heat release from additive injection valve (J)
Hpipe: Heat release from the first supply passage (J)
Hpump: Heat dissipation from the pump (J)

The above formula (1) is derived as follows.
The amount of electric power Epump supplied to the electric pump within a predetermined time can be expressed as the following equation (2) according to the law of energy conservation.
Epump [J] = Pad x Vad + H [J] (2)
Vad: Total amount of pumping additive (ml)
H: Total amount of heat released / inflow (J)

  Here, the additive relative pressure Pad can be obtained by subtracting the sensor value Patm of the atmospheric pressure sensor from the sensor value Psens of the pressure sensor. Further, the total amount Vad of the feed additive corresponds to the total amount of the injection amount Qdos from the additive injection valve and the reflux amount Qbf of the additive refluxed to the storage tank through the reflux passage. Further, the total amount of released / inflowed heat H corresponds to the total amount of the heat release amount Hdos from the additive injection valve, the heat release amount Hpipe from the first supply passage, and the heat release amount Hpump from the electric pump.

Therefore, the above equation (2) is replaced as the following equation (3).
Epump [J] = Pad × (Qdos + Qbf) + (Hdos + Hpipe + Hpump) [J] (3)
The above equation (1) is derived from this equation (3), and the actual injection amount Qdos injected from the additive injection valve is calculated.

FIG. 3 shows a control chart specifically showing an example of a method for calculating the actual injection amount of the additive performed in the DCU 60.
First, the supply power Epump to the pump is calculated by multiplying the current value Apump sent to the pump by the battery voltage Vb.

Also, by estimating the pump temperature Tpump using the map based on the current value Apump, subtracting the sensor value Tenv of the outside air temperature sensor, and multiplying by the pump surface area εpump and the pump heat transfer coefficient hpump Then, an increase / decrease amount Hpump of the heat amount from the pump is calculated.
Further, the temperature Tdos of the additive injection valve is estimated using a map based on the current Ados energized to the additive injection valve, and after subtracting the sensor value Tenv of the outside air temperature sensor, the additive injection valve By multiplying the surface area εdos and the heat transfer coefficient hdos of the additive injection valve, the increase / decrease amount Hdos of the heat amount from the additive injection valve is calculated.
Furthermore, after subtracting the sensor value Tenv of the outside air temperature sensor from the sensor value Tpipe of the temperature sensor provided in the first supply passage, the surface area εpipe of the first supply passage and the heat transfer coefficient hpipe of the first supply passage are obtained. By multiplying, the increase / decrease amount Hpipe of the heat amount from the first supply passage is calculated.

The calculated heat amount increase / decrease amount Hpump from the pump, the heat amount increase / decrease amount Hdos from the additive injection valve, and the heat amount increase / decrease amount Hpipe from the first supply passage are subtracted from the supply power Epump to the pump.
In addition, the sensor value Patm of the atmospheric pressure sensor is subtracted from the sensor value Psens of the pressure sensor provided in the first supply passage to obtain the relative pressure Pad of the additive, and the map is based on the value of the relative pressure Pad. The value obtained by multiplying the return amount Qbf of the additive estimated by using the value is further subtracted from the supply power Epump to the pump.

  Thus, the actual injection amount Qdos injected from the additive injection valve is calculated by subtracting the minus amount of the released energy from the supply power Epump to the pump by the additive relative pressure Pad. Is done.

Returning to FIG. 2, the abnormality determination unit performs abnormality determination of the additive supply device using the required injection amount calculated by the required injection amount calculation unit and the actual injection amount Qdos calculated by the actual injection amount calculation unit. Part. In the DCU 60 of the present embodiment, the difference between the required injection amount and the actual injection amount Qdos is obtained, and the value is compared with a reference value, so that the abnormality determination of the additive supply device is performed.
In other words, if the difference between the two values exceeds the reference value, the appropriate injection amount is not secured, and it is considered that an abnormality has occurred in any part of the additive supply device. It is determined that there is. When an abnormality is detected in the additive supply device, a signal is transmitted to the alarm means to notify the driver or the like.

  In addition to the method of comparing the difference between the required injection amount and the actual injection amount Qdos with a reference value, the additive supply device abnormality determination is performed by obtaining the ratio of the actual injection amount Qdos to the required injection amount and determining the ratio as a predetermined reference It can also be configured to compare with a value.

The injection command value correction unit compares the required injection amount calculated by the required injection amount calculation unit with the actual injection amount Qdos calculated by the actual injection amount calculation unit, and the actual injection amount matches the required injection amount. In this way, the addition instruction value is corrected based on the comparison result.
For example, the addition instruction value can be set by calculating the ratio of the difference between the required injection amount and the actual injection amount Qdos with respect to the required injection amount, and multiplying the required injection amount by the inverse of the ratio. . When comprised in this way, the addition instruction | indication value sent with respect to the operation apparatus of an additive injection valve will differ from the calculated request | requirement injection amount. However, because the actual injection amount approximates the required injection amount due to an abnormality occurring in the additive supply device, appropriate additive injection control is performed as a result.

Note that the DCU 60 in the exhaust purification apparatus of the present embodiment is configured to obtain the actual injection amount that is injected during a period in which the heaters provided in the first supply passage and the electric pump are not operating. . This is because the heat balance model by the operation of the heater is complicated, and the reliability of the calculated actual injection amount may be lowered.
However, if it is possible to prepare a heat balance model with high accuracy by operating the heater based on experimental values, etc., the actual injection will take into account the increase in the amount of heat from the heater even during the operation of the heater. The amount can be calculated.

  According to the additive actual injection amount verification device, additive supply device abnormality determination device, and additive supply device control device of the present invention described above, the actual additive injection amount is accurately based on the energy balance. Therefore, the abnormality determination of the additive supply device and the correction of the additive addition instruction value can be performed with high accuracy. In the embodiment described above, an example in which a urea solution is used as an additive has been described. However, for example, the present invention can also be applied to an exhaust purification device that supplies unburned fuel (HC) to the upstream side of the catalyst. .

It is a figure showing an example of composition of an exhaust-air-purification device concerning an embodiment of the invention. It is a block diagram which shows the structural example of the control apparatus (DCU) of the additive supply apparatus with which the exhaust gas purification apparatus of this embodiment was equipped. It is a control chart which shows the specific example of the calculation method of the actual injection amount of an additive.

Explanation of symbols

10: exhaust purification device, 11: exhaust pipe, 13: reduction catalyst, 15 · 16: temperature sensor, 17: NO _X sensor, 20: additive supply device, 31: additive injection valve, 33/35: temperature sensor, 40: Pump module, 41: Electric 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: reflux passage, 60: additive supply device control unit (DCU), 71: reverting valve, 92, 93, 94, 95, 96, 97: heater

Claims (5)

An additive is supplied to the exhaust upstream side of the reduction catalyst disposed in the exhaust passage of the internal combustion engine, and is provided in an exhaust purification device that reduces and purifies nitrogen oxides in the exhaust with the reduction catalyst, and pumps the additive. An electric pump, an additive injection valve that performs injection control of the additive pumped from the electric pump, an additive supply passage disposed between the electric pump and the additive injection valve, In the additive actual injection amount verification device for verifying the injection amount of the additive in the additive supply device comprising:
Based on the energy balance received or released by the additive supply system of the additive supply device within a predetermined period, the additive injection valve is actually injected within the predetermined period. An additive actual injection amount verification device comprising an actual injection amount calculation unit for calculating an actual injection amount of the additive.   The actual injection amount calculation unit is configured to increase or decrease the amount of electric power supplied to the electric pump, the amount of heat of the additive supply system, and the pressure in the additive supply passage at least within the predetermined period. 2. The additive actual injection amount verification device according to claim 1, wherein an actual injection amount of the additive is calculated based on information on the amount.   The additive actual injection amount verification device according to claim 1 or 2, wherein the calculation of the actual injection amount is executed when heating control or cooling control of the additive supply system is not performed. . An additive is supplied to the exhaust upstream side of the reduction catalyst disposed in the exhaust passage of the internal combustion engine, and is provided in an exhaust purification device that reduces and purifies nitrogen oxides in the exhaust with the reduction catalyst, and pumps the additive. An electric pump, an additive injection valve that performs injection control of the additive pumped from the electric pump, an additive supply passage disposed between the electric pump and the additive injection valve, In the abnormality diagnosis device of the additive supply device comprising
A required addition amount calculation unit for calculating a required addition amount of the additive to be supplied to the exhaust passage;
Based on the energy balance received or released by the additive supply system of the additive supply device within a predetermined period, the additive injection valve is actually injected within the predetermined period. An actual injection amount calculation unit for calculating the actual injection amount of the additive;
An abnormality determination unit that performs abnormality diagnosis of the additive supply device by comparing the required addition amount and the actual injection amount;
An abnormality determination device for an additive supply device, comprising: An additive is supplied to the exhaust upstream side of the reduction catalyst disposed in the exhaust passage of the internal combustion engine, and is provided in an exhaust purification device that reduces and purifies nitrogen oxides in the exhaust with the reduction catalyst, and pumps the additive. An electric pump, an additive injection valve that performs injection control of the additive pumped from the electric pump, an additive supply passage disposed between the electric pump and the additive injection valve, In the control device of the additive supply apparatus comprising
A required addition amount calculation unit for calculating a required addition amount of the additive to be supplied to the exhaust passage;
Based on the energy balance received or released by the additive supply system of the additive supply device within a predetermined period, the additive injection valve is actually injected within the predetermined period. An actual injection amount calculation unit for calculating the actual injection amount of the additive;
An addition instruction value correction unit that compares the required addition amount with the actual injection amount and corrects an addition instruction value that is a source of a control signal of the additive injection valve based on the result;
A control device for an additive supply device.

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