JP2019105188A - Reducing agent feeding device, exhaust emission control system and control method for reducing agent feeding device - Google Patents

Abstract

To provide a reducing agent feeding device for accurately detecting a temperature of a reducing agent injection valve mounted to an exhaust pipe on the upstream side of a reduction catalyst for reducing and eliminating NOx in exhaust gas in an internal combustion engine, an exhaust emission control system and a control method for a reducing agent feeding device.SOLUTION: A reducing agent feeding device supplies a reducing agent to an exhaust pipe on the upstream side of a reduction catalyst for reducing and eliminating NOx in exhaust gas in an internal combustion engine. The reducing agent feeding device includes: a reducing agent injection valve mounted to the exhaust pipe and injecting the reducing agent into the exhaust pipe; and a control device for controlling the reducing agent injection valve. The control device includes: a reducing agent injection valve coil temperature detection section for detecting a temperature of an electromagnetic coil part of the reducing agent injection valve; an internal combustion engine operating state detection section for detecting an operating state value of the internal combustion engine; and a vehicle traveling state detection section for detecting a traveling state value of a vehicle mounted with the internal combustion engine. A temperature of the reducing agent injection valve is estimated based on the temperature of the electromagnetic coil part of the reducing agent injection valve, the operating state value of the internal combustion engine, and the traveling state value of the vehicle mounted with the internal combustion engine.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a reducing agent supply device for supplying a reducing agent to an exhaust pipe upstream of a reduction catalyst that reduces and purifies NOx in the exhaust gas of an internal combustion engine, an exhaust gas purification system, and a control method of the reducing agent supply device.

It might contain NO _X in the exhaust gas of an internal combustion engine such as a diesel engine (nitrogen oxides). In order to remove the NO _x in the exhaust gas, a urea selective catalytic reduction (SCR) system including a reduction catalyst that reduces and purifies the NO _x is provided. Urea SCR systems use urea water as the reducing agent to decompose the NO _X by reacting with NO _X in the exhaust ammonia produced from urea water.

  In the urea SCR system, urea water is supplied from a tank for urea water into the exhaust passage via a reductant injection valve. The tank for urea water is provided with a temperature sensor for detecting the temperature of urea water, but the reducing agent injection valve arranged in the vicinity of the exhaust pipe may be heated or cooled from its surroundings However, the temperature of the reducing agent injection valve is not necessarily the same as the temperature of urea water in the tank for urea water. Thus, a technique for more accurately detecting the temperature of the reducing agent injection valve is disclosed.

JP, 2016-109086, A

  In the exhaust gas purification system described in Patent Document 1, as a method of detecting the temperature of the injector (reductant injection valve), it is described that an injector temperature sensor is disposed in the injector and the temperature of the injector is directly measured. However, when the injector temperature sensor is disposed in the injector, the size of the injector becomes large, and there is a problem that the mountability of the injector is deteriorated. Further, Patent Document 1 discloses that the temperature of the injector and the temperature of the aqueous urea in the aqueous urea tank are approximately proportional to each other, and the temperature of the injector is estimated from the temperature of the aqueous urea in the aqueous tank. It is done. However, the supply of heat in the process of being supplied from the tank to the injector is not always constant, and there is a possibility that the temperature of the injector can not be accurately estimated. In particular, when the temperature of the injector is estimated to be lower than the actual temperature, appropriate cooling measures can not be performed, the heat resistance temperature of the injector may be exceeded, and the injector may be thermally damaged.

  The present invention has been made in view of the above problems, and an object of the present invention is to be able to more accurately detect the temperature of the reducing agent injection valve, and the temperature of the reducing agent injection valve is An object of the present invention is to provide a reductant supply device, an exhaust gas purification system, and a control method of the reductant supply device capable of taking appropriate cooling measures when there is a possibility that the threshold value is exceeded.

  To solve the above problems, according to one aspect of the present invention, in a reducing agent supply device for supplying a reducing agent to an exhaust pipe upstream of a reduction catalyst that reduces and purifies NOx in the exhaust gas of an internal combustion engine, The reducing agent supply device includes a reducing agent injection valve attached to the exhaust pipe and injecting the reducing agent into the exhaust pipe, and a control device that controls the reducing agent injection valve, and the control device includes: A reducing agent injection valve coil temperature detection unit for detecting a temperature of an electromagnetic coil portion of a reducing agent injection valve, an internal combustion engine operation state detection unit for detecting an operation state value of an internal combustion engine, and traveling of a vehicle equipped with the internal combustion engine Based on a vehicle traveling state detecting unit for detecting a state value, a temperature of an electromagnetic coil portion of the reducing agent injection valve, a driving state value of the internal combustion engine, and a traveling state value of a vehicle equipped with the internal combustion engine Temperature of the reducing agent injection valve And a reducing agent injection valve temperature estimating unit for estimating the degree.

Further, in order to solve the above-mentioned problems, according to another aspect of the present invention, reducing agent injection for supplying a reducing agent to an exhaust pipe upstream of a reducing catalyst that reduces and purifies NOx in the exhaust of an internal combustion engine In a control method of a reducing agent supply device having a valve, the control method includes a step of detecting a temperature of an electromagnetic coil portion of a reducing agent injection valve, a step of detecting an operating state value of an internal combustion engine, and the internal combustion engine And detecting the driving condition value of the vehicle, the temperature of the electromagnetic coil portion of the reducing agent injection valve, the driving condition value of the internal combustion engine, and the driving condition value of the vehicle on which the internal combustion engine is mounted. And estimating the temperature of the reducing agent injection valve based on the control method.

  As described above, according to the present invention, the reducing agent injection is performed based on the temperature of the electromagnetic coil portion of the reducing agent injection valve, the operating state value of the internal combustion engine, and the traveling state value of the vehicle equipped with the internal combustion engine. Since the temperature of the valve can be accurately estimated, for example, if the temperature of the reducing agent injection valve is expected to be high, appropriate cooling measures can be taken, and the heat of the reducing agent injection valve can be taken. Damage can be avoided.

It is a schematic diagram which shows the structural example of the exhaust gas purification system containing the reducing agent supply apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structural example of the control apparatus of the reducing agent supply apparatus which concerns on the embodiment. It is a flowchart which shows the example of the control method of the reducing agent supply apparatus which concerns on the embodiment. It is explanatory drawing which shows an example of the estimation method of front-end | tip temperature of a reducing agent injection valve.

  The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. In the present specification and the drawings, components having substantially the same functional configuration will be assigned the same reference numerals and redundant description will be omitted.

<1. Overall Configuration of Vehicle Exhaust Purification System>
A configuration example of exhaust gas purification mounted on a vehicle to which the reducing agent supply device according to the present embodiment can be applied will be described. FIG. 1 is a schematic view showing a configuration example of an exhaust purification system 10.

  The exhaust purification system 10 is provided in an exhaust system of an internal combustion engine 5 such as a diesel engine or a gasoline engine. In the present embodiment, an example in which the internal combustion engine 5 is a diesel engine will be described. In the exhaust gas purification system 10, a reduction catalyst 13 is disposed in the exhaust pipe 11 of the internal combustion engine 5, and includes a reducing agent supply device 30 that supplies urea water into the exhaust pipe 11 upstream of the reduction catalyst 13.

Reduction catalyst 13 is a catalyst for reducing NO _X contained in the exhaust of an internal combustion engine 5. Reduction catalyst 13, by allowing adsorption of ammonia (NH ₃₎ generated from the urea water supplied, the NO _X and NH ₃ in the exhaust gas flowing into the reduction catalyst 13 is reduced reaction by the reducing agent supply device 30 Decomposition of NO _x into water (H ₂ O) and nitrogen (N ₂ ).

The reducing agent supply device 30 includes a storage tank 50 for storing urea water which is a reducing agent, a reducing agent injection valve 31 fixed to the exhaust pipe 11 upstream of the reducing catalyst 13, and urea water pumped out of the storage tank 50. , The reducing agent first passage 60 connecting the storage tank 50 and the pump 41, the reducing agent second passage 61 connecting the pump 41 and the reducing agent injection valve 31, and reduction Pressure sensor 43 for measuring the pressure of the reducing agent in the agent second passage 61, a tank temperature sensor 51 for measuring the temperature of the reducing agent attached to the storage tank 50 and measuring the temperature of the reducing agent, signals of various sensors And a reducing agent injection control device (control device) 100 that controls the pump 41 and the reducing agent injection valve 31 based on the above. As urea water which is a reducing agent, for example, urea water having a concentration of about 32.5% is used. Reducing agent injection control device 100, the supply amount of the reducing agent, and the concentration of NO _X contained in the exhaust, the temperature of the reduction catalyst 13, is set on the basis of the amount of adsorption of NH ₃ or the like in the reduction catalyst 13, the reducing catalyst outflow of the nO _X or NH ₃ to the downstream side of the 13 so as not to exceed the allowable value, it controls the pump 41 and the reducing agent injection valve 31 or the like.

  As the pump 41, for example, an electric diaphragm pump or an electric gear pump is used. A signal from the pressure sensor 43 that measures the pressure of the reducing agent in the reducing agent second passage 61 is transmitted to the reducing agent injection control device 100, and the reducing agent injection control device 100 is based on the sensor signal of the pressure sensor 43. The output of the pump 41 is feedback-controlled so that the pressure of the reducing agent supplied to the reducing agent injection valve 31 is maintained at a predetermined target value.

  As the reducing agent injection valve 31, for example, an electromagnetically driven reducing agent injection valve whose valve opening and closing are switched by turning on and off of the current supply is used. The electromagnetically driven reductant injection valve 31 includes an electromagnetic coil as an actuator, and the piston moves and opens when the electromagnetic coil is energized. In the present embodiment, the pressure of the reducing agent supplied to the reducing agent injection valve 31 is controlled to be a predetermined target value, and the reducing agent injection control device 100 performs the injection according to the instructed injection amount of the reducing agent. Control the time.

The exhaust purification system 10 further includes an exhaust temperature sensor 21, an NO _x concentration sensor 23, and an outside air temperature sensor 25. The exhaust temperature sensor 21 is provided in the exhaust pipe 11 upstream of the reduction catalyst 13 and detects the exhaust temperature. The NO _x concentration sensor 23 is provided in the exhaust pipe 11 downstream of the reduction catalyst 13 and mainly detects the NO _x concentration (downstream NO _x concentration) on the downstream side of the reduction catalyst 13. The outside air temperature sensor 25 detects the outside air temperature around the reducing agent injection valve 31. Signals output from these sensors are transmitted to the reductant injection control device 100.

<2. Configuration Example of Reductant Injection Control Device>
Next, a configuration example of the reducing agent injection control device 100 according to the present embodiment will be described. FIG. 2 is a block diagram for describing a configuration example of the reducing agent injection control device 100 according to the present embodiment.

  The reducing agent injection control device 100 includes a processor such as a central processing unit (CPU) or a micro processing unit (MPU) and an electric circuit, and the processor executes various computer programs to realize various functions. It is an apparatus.

  The reducing agent injection control device 100 includes a reducing agent injection valve temperature estimating unit 112, a reducing agent injection valve coil temperature detecting unit 114, an internal combustion engine operating condition detecting unit 116, a vehicle traveling condition detecting unit 118, and a cooling control unit 120. And a temperature detection unit 122, a storage unit 126, and the like.

The reducing agent injection control device 100 is configured to be able to acquire an applied voltage V_inj to the reducing agent injection valve 31 and a current I_inj flowing through the reducing agent injection valve 31. The reducing agent injection control device 100 additionally includes a sensor signal S_nox of the NOx concentration sensor 23, a sensor signal S_tankt of the tank temperature sensor 51, a sensor signal S_pres of the pressure sensor 43, a sensor signal S_exht of the exhaust temperature sensor 21, and an outside air temperature sensor. Twenty-five sensor signals S_atmt are acquired from each sensor. Furthermore, the reducing agent injection control device 100 is configured to be able to obtain the rotational speed signal S_espeed of the internal combustion engine 5, the fuel injection amount signal S_fuel of the internal combustion engine 5, and the speed signal S_vspeed of the vehicle 1 from the internal combustion engine control device 200 (FIG. 1). It is done. Further, in the present embodiment, the reducing agent injection control device 100 and the internal combustion engine control device 200 are represented as separate control devices, but may be one control device having both functions. Furthermore, CAN (Controller Area Network) etc. may be used as a communication means between each sensor or control device. The above-mentioned S_fuel is a signal representing a fuel injection amount injected from the injector 6 (FIG. 1) to the internal combustion engine 5, and S_espeed is an output of the rotational speed sensor 7 (FIG. 1) for measuring the rotational speed of the internal combustion engine 5. S_vspeed is an output signal of the vehicle speed sensor 2 (FIG. 1) for detecting the speed of the vehicle 1 (FIG. 1) on which the internal combustion engine 5 is mounted.

(2-1. Storage unit)
The storage unit 126 is configured of one or more storage elements such as a random access memory (RAM) or a read only memory (ROM). The storage unit 126 stores computer programs executed by the processor, control parameters used for computation, computation results by the processor, acquired sensor values, and the like.

(2-2. Reductant injection valve coil temperature detection unit)
The reducing agent injection valve coil temperature detection unit 114 estimates the temperature of the electromagnetic coil portion of the reducing agent injection valve 31. That is, the reducing agent injection valve coil temperature detection unit 114 calculates the coil resistance value of the reducing agent injection valve 31 from the voltage V_inj applied to the reducing agent injection valve 31 and the current I_inj flowing through the reducing agent injection valve 31 The temperature of the coil portion of the reducing agent injection valve 31 is estimated based on the resistance value. For example, if the relationship between the temperature of the coil portion measured in advance and the coil resistance value is stored as a map in the storage unit 126, the coil portion of the reducing agent injection valve 31 is calculated based on the calculated coil resistance value. The temperature T_coil of can be estimated.

(2-3. Internal combustion engine operating condition detection unit)
Internal combustion engine operating state detection unit 116 detects an operating state value of internal combustion engine 5. For example, the internal combustion engine operating state detection unit 116 uses the rotational speed signal S_espeed of the internal combustion engine 5 as the operating state value of the internal combustion engine 5 to set the rotational speed Speed_e of the internal combustion engine 5 and the fuel injection amount signal S_fuel of the internal combustion engine 5 from the internal combustion engine The fuel injection amount Fuel_e of 5 is detected.

(2-4. Vehicle running state detection unit)
Vehicle traveling state detection unit 118 detects a traveling state value of vehicle 1 on which internal combustion engine 5 is mounted. For example, the vehicle travel state detection unit 118 detects the speed Speed_v of the vehicle 1 from the speed signal S_vspeed of the vehicle 1 as the travel state value of the vehicle 1.

(2-5. Temperature detection unit)
The temperature detection unit 122 detects the reducing agent temperature Temp_tank in the storage tank 50 from the sensor signal S_tankt of the tank temperature sensor 51, detects the exhaust temperature Temp_exh from the sensor signal S_exht of the exhaust temperature sensor 21, and detects the outside air temperature sensor 25. The ambient temperature Temp_atm around the reducing agent injection valve 31 is detected from the signal S_atmt.

(2-6. Reductant injection valve temperature estimation unit)
The reducing agent injection valve temperature estimation unit 112 detects the temperature T_coil of the coil portion of the reducing agent injection valve 31 estimated by the reducing agent injection valve coil temperature detection unit 114 and the internal combustion engine 5 detected by the internal combustion engine operation state detection unit 116. The tip temperature T_tip of the reducing agent injection valve 31 is calculated based on the driving state value of and the traveling state value of the vehicle 1 detected by the vehicle traveling state detection unit 118. Here, the tip of the reducing agent injection valve 31 refers to an injection hole for injecting the reducing agent in the reducing agent injection valve 31 and a portion around the injection hole. In the present embodiment, the reducing agent injection valve temperature estimation unit 112 estimates the temperature T_coil of the electromagnetic coil portion of the reducing agent injection valve 31 and sets the operating state value of the internal combustion engine 5 to the temperature T_coil of the electromagnetic coil portion. The temperature increase amount of the reducing agent injection valve 31 calculated based on the above is added, and the temperature decrease amount of the reducing agent injection valve 31 calculated based on the traveling state value of the vehicle 1 is subtracted to The tip temperature T_tip is calculated. Hereinafter, an example of the reducing agent injection valve temperature estimation unit 112 according to the present embodiment will be described in detail with reference to FIG.

  The exhaust heat quantity Q1a discharged from the internal combustion engine 5 can be calculated based on the rotational speed Speed_e of the internal combustion engine 5 and the fuel injection amount Fuel_e. Part A of FIG. 4 calculates the exhaust heat quantity Q1a discharged from the internal combustion engine 5 from the rotational speed Speed_e and the fuel injection amount Fuel_e. Further, the part A calculates the amount of heat Q1 received by the reducing agent injection valve 31 from the amount of heat of exhaust Q1a discharged from the internal combustion engine 5, and sends the result to the part B. Here, when calculating Q1, the calculation may be performed taking into consideration the exhaust temperature Temp_exh which is the exhaust temperature near the reducing agent injection valve 31. For example, if the exhaust gas temperature Temp_exh is lower than the expected temperature with respect to the exhaust heat quantity Q1a, the exhaust pipe 11 is not sufficiently warmed, and the generated exhaust heat is used to raise the temperature of the exhaust pipe 11 Since the amount of heat Q1 received by the valve 31 may be small, the amount of heat Q1 received by the reducing agent injection valve 31 can be calculated more accurately by correcting this. As a method for calculating the exhaust heat quantity Q1a from the rotational speed Speed_e and the fuel injection amount Fuel_e in part A, for example, a map describing the relationship between the rotational speed Speed_e and the fuel injection amount Fuel_e and the exhaust heat quantity Q1a is used The map is stored in the storage unit 126, and the reducing agent injection valve temperature estimation unit 112 refers to this as needed to calculate the exhaust heat quantity Q1a. It is conceivable that a map is similarly used for a method of calculating the heat quantity Q1 received by the reducing agent injection valve 31 from the exhaust heat quantity Q1a. Furthermore, the corresponding maps stored in the storage unit 126 may be used also in calculations in portions B, C, D, and E of FIG. 4 described below.

The subsequent part B calculates the temperature rise T1 at the tip of the reducing agent injection valve 31 which has received the heat from the heat quantity Q1 received by the reducing agent injection valve 31.

When the vehicle 1 travels, the reducing agent injection valve 31 attached to the exhaust pipe 11 receives the traveling wind and is thus deprived of heat. The higher the traveling speed, the stronger the traveling wind, and therefore the greater the amount of heat that is lost. Based on this relationship, the C portion in FIG. 4 calculates the heat release amount Q2 from the reducing agent injection valve 31 from the speed Speed_v of the vehicle 1, and sends the result to the D portion. Since the heat radiation effect is higher as the outside air temperature Temp_atm is lower, when calculating Q2, the outside air temperature Temp_atm may be taken into consideration to calculate Q2.

The subsequent part D calculates the temperature decrease amount T2 at the tip of the reducing agent injection valve 31 from the heat release amount Q2.

The reducing agent injection valve temperature estimating unit 112 adds the temperature increase amount T1 to the temperature T_coil of the coil portion of the reducing agent injection valve 31 and subtracts the temperature decrease amount T2, and further performs arithmetic processing such as delay time in the E portion. The tip temperature T_tip of the reducing agent injection valve 31 is calculated.

(2-6. Cooling control unit)
The cooling control unit 120 performs cooling control when the tip temperature T_tip estimated by the reducing agent injection valve temperature estimation unit 112 exceeds the threshold T_thre. For example, the cooling control unit 120 increases the injection amount of the reducing agent injected from the reducing agent injection valve 31. Specifically, the cooling control unit 120, capable of generating NH ₃ amount of combination of the NH ₃ amount of excess or deficiency relative to NH ₃ amount and the target adsorbed NH ₃ amount needed to purify NO _X in the exhaust gas Increase correction is performed on the calculated injection amount Q_urea of urea water. Thus, the amount of heat released from the reducing agent injection valve 31 to the reducing agent is increased, and the cooling efficiency of the reducing agent injection valve 31 is improved. The command injection amount Q_urea of urea water may be calculated by the cooling control unit 120 or may be calculated by another control unit in the reducing agent injection control device 100. When determining the increase correction amount, it may be determined in consideration of the reducing agent temperature Temp_tank in the storage tank 50. The lower the temperature Temp_tank of the reducing agent, the higher the cooling effect. Therefore, when the temperature Temp_tank of the reducing agent is lower, the amount of increase correction can be reduced. As another cooling method, the cooling control unit 120 can decrease the tip temperature of the reducing agent injection valve 31 by temporarily reducing the fuel injection amount of the internal combustion engine 5 to reduce the exhaust heat quantity Q1a. A signal for reducing the fuel injection amount is generated by the cooling control unit 120 and sent from the reductant injection control device 100 to the internal combustion engine control device 200 so that the internal combustion engine control device 200 reduces the fuel injection amount from the injector 6 Control.

<3. Operation Example of Reductant Injection Control Device>
Next, an operation example of the reducing agent injection control device 100 according to the present embodiment will be described.

  FIG. 3 is an explanatory diagram of an example of a flow from calculation processing for estimating the tip temperature T_tip of the reducing agent injection valve 31 to cooling control. In step S <b> 11, the reducing agent injection valve coil temperature detection unit 114 calculates the coil temperature T_coil of the reducing agent injection valve 31.

  Next, in step S13, the internal combustion engine operating state detection unit 116 detects the operating state value of the internal combustion engine 5. For example, the operating state value of the internal combustion engine 5 is the rotational speed Speed_e of the internal combustion engine 5 and the fuel injection amount Fuel_e.

  Next, in step S15, the vehicle travel state detection unit 118 detects a travel state value of the vehicle 1 on which the internal combustion engine 5 is mounted. For example, the traveling state value of the vehicle 1 is the speed Speed_v of the vehicle 1. The order of S11, S13, and S15 is not limited to this order, and any step may be the first and any step may be the second.

  Next, in step S17, the reducing agent injection valve temperature estimation unit 112 calculates the reducing agent injection based on the coil temperature T_coil of the reducing agent injection valve 31, the operating state value of the internal combustion engine 5, and the traveling state value of the vehicle 1. The tip temperature T_tip of the valve is estimated. The specific estimation method is as described above with reference to FIG.

  In step S19, the cooling control unit 120 determines whether the tip temperature T_tip exceeds a threshold T_thre. The threshold value T_thre is set to an appropriate value smaller than the heat resistant temperature so as not to cause thermal damage to the reducing agent jet valve 31 in consideration of the heat resistant temperature of the reducing agent injection valve 31. If the tip temperature T_tip is less than or equal to the threshold T_thre (S19 / No), the reducing agent injection control device 100 returns to step S11 and repeats the process because it is not necessary to execute the cooling of the reducing agent injection valve 31.

On the other hand, when the tip end temperature T_tip exceeds the threshold value T_thre (S19 / Yes), the cooling control unit 120 executes the cooling control of the reducing agent injection valve 31 (step S21). For example, the cooling control unit 120 increases the injection amount of the reducing agent injected from the reducing agent injection valve 31. Specifically, the NH ₃ amount and the target NH ₃ NH ₃ amount of urea water that is capable of producing calculates a combination of the NH ₃ amount of excess or deficiency relative adsorbed amount needed to purify NO _X in the exhaust gas Increase correction is performed on the instructed injection amount Q_urea. Thereby, the amount of heat release from the reducing agent injection valve 31 to the urea water is increased, and the cooling efficiency of the reducing agent injection valve 31 is improved. Even when the injection amount of urea water is increased and NH ₃ flows out to the downstream side of the reduction catalyst 13, NH ₃ is not removed by the ammonia slip catalyst (not shown) disposed on the downstream side of the reduction catalyst 13. It is oxidized and decomposed. In addition, the cooling control unit can also temporarily decrease the fuel injection amount of the internal combustion engine 5 as cooling control of the reducing agent injection valve 31.

  As described above, the reducing agent injection device 30 according to the present embodiment can thereby reduce the deviation between the actual tip temperature of the reducing agent injector 31 and the tip temperature T_tip that is estimated. For this reason, since the tip end temperature T_tip is estimated to be low, cooling control can not be performed, and thermal damage due to excessive temperature rise of the tip end temperature can be suppressed. Alternatively, in order to prevent the thermal damage of the reducing agent injection valve 31, it is possible to suppress the consumption of the cooling reducing agent more than necessary.

In the above description, the reducing agent injection control device 100 including the reducing agent injection valve temperature estimation unit 112 estimates the tip temperature T_tip of the reducing agent injection valve 31, and performs cooling control so that the tip temperature T_tip does not exceed the threshold temperature. The temperature may be estimated except for the tip portion of the reducing agent injection valve 31, and the cooling control may be performed so that the temperature of the portion does not exceed the threshold temperature. In that case, the reducing agent The injection valve temperature estimation unit 112 performs calculation using a map different from the map for estimating the temperature of the tip portion described above in order to estimate the temperature other than the tip portion. The threshold temperature is also determined based on the heat resistance of that portion. For example, the temperature of the electrical connector portion of the reducing agent injection valve 31 may be estimated, and cooling control may be performed so that the electrical connector portion does not exceed the threshold temperature.

  Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that those skilled in the art to which the present invention belongs can conceive of various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also fall within the technical scope of the present invention.

Reference Signs List 1 vehicle 2 vehicle speed sensor 5 internal combustion engine 6 injector 7 injector 7 rotational speed sensor 11 exhaust purification system 11 exhaust pipe 13 reduction catalyst 21 exhaust temperature sensor 23 downstream NO _X concentration sensor 25 ambient temperature sensor 30 reducing agent supply device 31 reducing agent injection valve 41 Pump 43 Pressure sensor 50 Storage tank 51 Temperature sensor 60 Reductant first passage 61 Reductant second passage 100 Reductant injection control device (control device)
112 reductant injection valve temperature estimation unit 114 reductant injection valve coil temperature detection unit 116 internal combustion engine operating condition detection unit 118 vehicle travel condition detection unit 120 cooling control unit 122 temperature detection unit 126 storage unit 200 internal combustion engine control device

Claims (8)

In a reducing agent supply device for supplying a reducing agent to an exhaust pipe upstream of a reduction catalyst that reduces and purifies NOx in the exhaust gas of an internal combustion engine,
The reducing agent supply device
A reducing agent injection valve attached to the exhaust pipe and injecting the reducing agent into the exhaust pipe;
A controller for controlling the reducing agent injection valve;
Equipped with
The controller is
A reducing agent injection valve coil temperature detection unit that detects the temperature of the electromagnetic coil portion of the reducing agent injection valve;
An internal combustion engine operating state detection unit for detecting an operating state value of the internal combustion engine;
A vehicle traveling state detection unit that detects a traveling state value of a vehicle equipped with the internal combustion engine;
The reduction is performed to estimate the temperature of the reducing agent injection valve based on the temperature of the electromagnetic coil portion of the reducing agent injection valve, the operating state value of the internal combustion engine, and the traveling state value of the vehicle on which the internal combustion engine is mounted. Agent injection valve temperature estimation unit,
A reducing agent supply device characterized by having. The reducing agent supply device according to claim 1, wherein a temperature of an electromagnetic coil portion of the reducing agent injection valve is determined based on a resistance value of a coil of the reducing agent injection valve. The reducing agent supply device according to claim 1 or 2, wherein the operating state value of the internal combustion engine includes a rotation speed of the internal combustion engine and a fuel injection amount. The reducing agent supply device according to any one of claims 1 to 3, wherein the traveling state value of the vehicle is a speed of the vehicle. The controller is
The reducing agent supply according to any one of claims 1 to 4, further comprising a cooling control unit that performs cooling control when the temperature of the reducing agent injection valve exceeds a predetermined threshold. apparatus.   An exhaust gas purification system comprising the reducing agent supply device according to any one of claims 1 to 5. In a control method of a reducing agent supply device having a reducing agent injection valve for supplying a reducing agent to an exhaust pipe upstream of a reduction catalyst which reduces and purifies NOx in exhaust gas of an internal combustion engine,
The control method is
Detecting the temperature of the electromagnetic coil portion of the reducing agent injection valve;
Detecting an operating state value of the internal combustion engine;
Detecting a traveling state value of a vehicle equipped with the internal combustion engine;
Estimating the temperature of the reducing agent injection valve based on the temperature of the electromagnetic coil portion of the reducing agent injection valve, the operating state value of the internal combustion engine, and the traveling state value of the vehicle on which the internal combustion engine is mounted When,
The control method of the reducing agent supply apparatus characterized by including. The control method is
The control method of the reducing agent supply device according to claim 7, further comprising the step of performing cooling control when the temperature of the reducing agent injection valve exceeds a predetermined threshold.

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