JP7035625B2 - Electronic control device for exhaust purification system - Google Patents

Description

The present invention relates to an electronic control device for an exhaust gas purification system.

Conventionally, a urea SCR (Selective Catalytic Reduction) system using urea as an exhaust gas purification system for purifying the exhaust gas of an internal combustion engine is known (see Patent Document 1). In the urea SCR system, nitrogen oxides (NOx) contained in the exhaust gas are reduced by adding urea to the exhaust pipe.

However, since urea water is an aqueous solution of urea, urea may precipitate as crystals on an injector exposed to high-temperature exhaust gas. When urea is deposited on the injector, the drive portion of the injector, the injection port, and the like are fixed, which causes the injector to malfunction. As a result, there is a problem that the purification rate of NOx is lowered due to the insufficient supply of urea water. Further, in the case of Patent Document 1, there is a problem that the determination of sticking of the injector is limited to the stop processing of the exhaust gas purification system.

International Publication WO2012 / 063530

Therefore, an object of the present invention is to provide an electronic control device for an exhaust gas purification system that determines sticking of an injector regardless of the time.

In the invention according to claim 1, the current acquisition unit acquires the current supplied to the injector as an output current value. Then, the determination unit determines whether or not the injector is stuck by using the output current value acquired by this current acquisition unit. The output current value changes depending on the operating state of the injector. For example, when urea water is injected from an injector, the output current value continues to increase from the start of operation of the injector to the start of injection of urea water. By acquiring the tendency of the output current value to change with time, it is possible to determine whether or not the injector is operating normally, that is, whether or not the injector is stuck. Also, the output current value is acquired during the operation of the exhaust purification system, such as during the operation of the injector. Therefore, the output current value is acquired regardless of a specific time such as when the exhaust gas purification system is stopped. Therefore, it is possible to determine the sticking of the injector regardless of the timing.

A block diagram showing a schematic configuration of an electronic control device of an exhaust gas purification system according to an embodiment. Schematic diagram showing an exhaust gas purification system according to one embodiment Schematic sectional view showing an example of an injector used in an exhaust gas purification system according to an embodiment. Schematic diagram showing the relationship between the normal control state, the sticking elimination control state, the valve opening pressure increase control state, the urea water pressure, and the target current value in the exhaust purification system according to one embodiment. Schematic diagram showing the relationship between the drive signal and the output current value in the exhaust gas purification system according to one embodiment. Schematic diagram showing the flow of processing by the electronic control device of the exhaust gas purification system according to one embodiment. Schematic diagram showing the flow of processing by the electronic control device of the exhaust gas purification system according to one embodiment. Schematic diagram showing the flow of processing by the electronic control device of the exhaust gas purification system according to one embodiment.

Hereinafter, the electronic control device of the exhaust gas purification system according to the embodiment will be described with reference to the drawings.
The exhaust gas purification system 10 according to the embodiment shown in FIG. 2 constitutes, for example, an SCR system in which urea water is added to the exhaust gas discharged from the internal combustion engine 11 mounted on the vehicle to reduce NOx contained in the exhaust gas. There is. The exhaust gas of the internal combustion engine 11 is discharged to the atmosphere through the exhaust passage 13 formed by the exhaust pipe member 12. The internal combustion engine 11 is, for example, a diesel engine. The exhaust purification system 10 may be applied not only to a diesel engine but also to a gasoline engine, a gas turbine engine, or the like as the internal combustion engine 11. Further, the exhaust gas purification system 10 is not limited to the in-vehicle internal combustion engine 11, and may be applied to a stationary internal combustion engine 11 such as a power generation unit.

The exhaust purification system 10 includes a urea water tank 14, a urea water pump 15, a urea water piping section 16, a pressure sensor 17, a reduction catalyst 18, an injector 19, and a temperature sensor 21. The urea water tank 14 stores an aqueous solution of urea, which is urea water. The urea water pump 15 discharges the urea water stored in the urea water tank 14 to the urea water passage 22 formed by the urea water piping unit 16. The reduction catalyst 18 is provided in the exhaust passage 13. The injector 19 is connected to the urea water tank 14 via the urea water passage 22. The urea water pump 15 supplies the urea water pumped from the urea water tank 14 to the injector 19 via the urea water passage 22. The injector 19 is provided on the exhaust pipe member 12. The injector 19 penetrates the exhaust pipe member 12 and its tip is exposed in the exhaust passage 13. The urea water supplied to the injector 19 is injected into the exhaust gas flowing through the exhaust passage 13. The injector 19 is provided on the inlet side of the reduction catalyst 18 in the flow direction of the exhaust gas in the exhaust passage 13. The exhaust gas discharged from the internal combustion engine 11 and the urea water injected from the injector 19 are mixed in the exhaust passage 13 and flow into the reduction catalyst 18. NOx contained in the exhaust is reduced by chemically reacting with urea contained in urea water in the reduction catalyst 18.

The temperature sensor 21 is provided in the injector 19. The temperature sensor 21 detects the temperature of the injector 19. The urea water pump 15 that supplies urea from the urea water tank 14 to the injector 19 is driven by a motor 23. The motor 23 generates a driving force by the electric power supplied from the battery 24. By driving the urea water pump 15 with the motor 23, the urea water stored in the urea water tank 14 is supplied to the injector 19.

The injector 19 has a body 31, a needle 32, and a drive unit 33 as shown in FIG. The body 31 is formed in a cylindrical shape and houses the needle 32 movably inside. The body 31 has a urea water inlet 34 and an injection port 35. The urea water inlet 34 is connected to the urea water passage 22. The needle 32 is reciprocating in the axial direction inside the body 31. The drive unit 33 has a coil 36 and a pressing member 37. The coil 36 generates a magnetic force that attracts the needle 32 by turning the energization on or off. The pressing member 37 applies a force to the needle in a direction opposite to the suction direction by the coil 36. As a result, the needle 32 is reciprocated in the axial direction by turning on or off the energization of the coil 36. The pressing member 37 can use, for example, hydraulic pressure or pneumatic pressure as long as the needle 32 is configured to apply a force in the direction opposite to the suction direction by the coil 36, and is not limited to an elastic body such as a spring.

The urea water inlet 34 and the injection port 35 are connected by a passage 38. The passage 38 has a body passage 41, a needle passage 42, and an injection passage 43. The body passage 41 penetrates the body 31 in the axial direction. The needle passage 42 is formed on the inner peripheral side of the cylindrical needle 32. The injection passage 43 is formed between the inner wall of the body 31 and the outer wall of the needle 32 in the vicinity of the tip of the body 31.

The needle 32 has a contact portion 44 near one end in the axial direction. When the contact portion 44 of the needle 32 comes into contact with the seat portion 45 of the body 31, the space between the passage 38 and the injection port 35 is blocked. As a result, the needle 32 is driven upward in FIG. 3 by the drive unit 33, and when the contact portion 44 of the needle 32 and the seat portion 45 of the body 31 are in contact with each other, urea water is not ejected from the injection port 35. On the other hand, the contact portion 44 of the needle 32 is separated from the seat portion 45 of the body 31, so that the passage 38 and the injection port 35 are connected. As a result, the needle 32 is driven downward in FIG. 3 by the drive unit 33, and when the contact portion 44 of the needle 32 and the seat portion 45 of the body 31 are separated from each other, urea water is ejected from the injection port 35.

The exhaust gas purification system 10 described above is controlled by the electronic control device 50 as shown in FIG. The electronic control device 50 is composed of a microcomputer having a CPU, ROM, and RAM (not shown). The electronic control device 50 controls each part of the vehicle on which the internal combustion engine 11 including the exhaust gas purification system 10 is mounted. As an example, the electronic control device 50 sets the injection amount of urea water to be injected from the injector 19 based on the amount and concentration of NOx contained in the exhaust detected by the NOx sensor (not shown) provided in the exhaust passage 13. do. In this case, the electronic control device 50 corrects the injection amount of urea water based on, for example, the amount of fuel supplied to the internal combustion engine 11 and the temperature of the exhaust gas flowing through the exhaust passage.

As shown in FIG. 1, the electronic control device 50 includes an injection control unit 51, a current acquisition unit 52, a determination unit 53, a elimination control unit 54, and a temperature acquisition unit 55. The electronic control device 50 executes a computer program stored in a ROM or an external storage medium (not shown), so that the injection control unit 51, the current acquisition unit 52, the determination unit 53, the elimination control unit 54, and the temperature acquisition unit 55 are executed. Is realized by software. The injection control unit 51, the current acquisition unit 52, the determination unit 53, the elimination control unit 54, and the temperature acquisition unit 55 may be realized in terms of hardware, and may be realized by cooperation between software and hardware. May be good.

As shown in FIG. 4, the electronic control device 50 controls the operating state of the exhaust gas purification system 10 to one of three states: a normal control state, a sticking elimination control state, and a valve opening force increase control state. The normal control state is a state in which the injector 19 is not fixed due to precipitation of urea or the like. That is, when the electronic control device 50 is in the normal control state, the injector 19 is set to the normal target current value I1, and the pressure of the urea water discharged from the urea water pump 15 is set to the pressure Pn. On the other hand, the sticking elimination control state is a state in which the pressure of the urea water is increased in order to eliminate the sticking occurring in the injector 19. That is, when the electronic control device 50 is in the sticking elimination control state, the injector 19 is set to the normal target current value I1, and the pressure of the urea water discharged from the urea water pump 15 is set from the pressure Pn in the normal control state. Also set to a high elimination pressure P1. Further, the valve opening force increase control state is a state in which the pressure of the urea water is increased in order to eliminate the sticking caused in the injector 19, and the force generated in the drive unit 33 is increased. That is, when the electronic control device 50 is in the valve opening force increase control state, the electronic control device 50 sets the target current value I2 larger than the normal target current value I1 to the injector 19, and the pressure of the urea water discharged from the urea water pump 15 is set. Is set to the elimination pressure P1. As a result, the electronic control device 50 controls the urea water pump 15 and the injector 19 constituting the exhaust gas purification system 10 to either a normal control state, a sticking elimination control state, or a valve opening force increase control state.

The injection control unit 51 is connected to the drive unit 33 of the injector 19. The injection control unit 51 controls on and off of the current supplied to the injector 19, and the magnitude of the current supplied to the injector 19. Specifically, by supplying an electric current to the drive unit 33 of the injector 19, the coil 36 generates a driving force for driving the needle 32. The injection control unit 51 controls the injection timing of urea water from the injector 19 by controlling the current supplied to the drive unit 33 of the injector 19. The injection control unit 51 sets a target current value I1 as a target value of the current supplied to the injector 19 in the normal control state. Further, the injection control unit 51 sets a target current value I2 larger than the target current value I1 as a target value of the current supplied to the injector 19 in the valve opening force increase control state. In this way, the injection control unit 51 sets the target current value I1 or the target current value I2 as the upper limit of the current supplied to the injector 19. The upper limit of the current supplied from the injection control unit 51 to the injector 19 is the target current value I1 or the target current value I2. Therefore, the magnetic attraction generated by the coil 36 of the drive unit 33 becomes a force corresponding to the target current value I1 or the target current value I2. That is, when the target current value I1 set in the injector 19 becomes the target current value I2, the magnetic attraction generated by the coil 36 of the drive unit 33 also increases.

The current acquisition unit 52 acquires the current supplied from the injection control unit 51 to the injector 19 as an output current value. Specifically, as shown in FIG. 5, when a drive signal is output from the injection control unit 51 to the drive unit 33 of the injector 19, the injection control unit 51 supplies a current to the coil 36 of the injector 19. That is, when the drive signal is output, a current flows through the coil 36 of the injector 19. At this time, the current supplied to the coil 36 changes with the passage of time. The current acquisition unit 52 acquires a current that changes with the passage of time, that is, a current flowing through the coil 36, as an output current value.

The determination unit 53 determines whether or not the injector 19 is stuck by using the output current value acquired by the current acquisition unit 52. Specifically, when the drive signal is output from the injection control unit 51, the determination unit 53 acquires the output current value flowing through the coil 36, for example, every few microseconds. Then, the determination unit 53 detects the amount of change in the output current value over time as the current gradient value. When the drive signal is output from the injection control unit 51, the current flowing through the coil 36 changes with the passage of time as described above. At this time, the current flowing through the coil 36 increases as the drive signal becomes “on”. Therefore, when the current flowing through the coil 36 is increasing, the amount of change in the output current value with time, that is, the current gradient value which is a differential value becomes a value larger than “0”. During this time, the suction force generated by the coil 36 also increases according to the magnitude of the supplied current. When the suction force generated by the coil 36 becomes larger than the force applied by the pressing member 37 to the needle 32, the needle 32 moves downward in FIG. 3 and the contact portion 44 separates from the seat portion 45. That is, the injector 19 opens the valve and starts spraying urea water. When the injector 19 is opened in this way, the current gradient value, which is the amount of change over time in the output current value, becomes “0”. The determination unit 53 specifies the output current value when the detected current gradient value becomes “0”, and defines the specified output current value as the specific current value Id. The detection of the current gradient value "0" is, for example, a method of detecting the value of "0" itself, or "0" when the gradient value falls below a specific positive value and then falls below a specific negative value. There is a method of detecting. Then, as shown in FIG. 4, the determination unit 53 compares the specified specific current value Id with the set values S1, S2, S3, S4, and S5.

The set value S1 shown in FIG. 4 corresponds to the target current value I2 in the valve opening force increase control state. Further, the set value S2 corresponds to the target current value I1 in the normal control state in which it is determined that the injector is not stuck. The set value S3 is a threshold value at the time of shifting from the valve opening force increase control state to the sticking elimination control state. The set value S4 is a threshold value at the time of shifting from the normal control state to the sticking elimination control state. The set value S5 is a threshold value at the time of shifting from the sticking elimination control state to the normal control state. These set values S1 to S5 are arbitrarily set according to the performance of the exhaust gas purification system 10 or the injector 19.

When the determination unit 53 determines that the injector 19 is stuck, the elimination control unit 54 implements elimination control for eliminating the sticking of the injector 19. The elimination control unit 54 raises the pressure of the urea water injected from the injector 19 from the pressure Pn to the elimination pressure P1 as elimination control. In this case, the elimination control unit 54 controls the urea water pump 15 based on the pressure of the urea water in the urea water passage 22 detected by the pressure sensor 17. As a result, when the elimination control is implemented, the pressure of the urea water supplied to the injector 19 becomes the elimination pressure P1 higher than the pressure Pn in the normal control state. As a result, the injector 19 is supplied with urea water having a elimination pressure P1 higher than the pressure Pn in the normal control state. As a result, the urea precipitated in the injector 19 is removed by the urea water having a elimination pressure of P1. As a result, the sticking in the injector 19 can be eliminated. The pressure Pn and the elimination pressure P1 are arbitrarily set according to the performance of the exhaust gas purification system 10 and the injector 19.

On the other hand, when the sticking of the injector 19 is not resolved by the elimination control by the elimination control unit 54, the injection control unit 51 increases the target current value from the target current value I1 to the target current value I2 and increases the target current. A current is supplied to the injector 19 with the value I2 as the upper limit. Therefore, the magnetic attraction generated by the coil 36 of the drive unit 33 increases in accordance with the increased target current value I2. As a result, the suction force generated by the coil 36 is increased, and the sticking of the injector 19 is eliminated.

The temperature acquisition unit 55 is connected to the temperature sensor 21. The temperature acquisition unit 55 acquires the temperature of the injector 19 through the temperature sensor 21. Specifically, the temperature acquisition unit 55 acquires the temperature of the coil 36 of the injector 19. When the coil 36 of the injector 19 is exposed to a high temperature, the capacity may be reduced or the coil 36 may be destroyed. When the target current value I1 is raised to the target current value I2, the calorific value of the coil 36 also increases. Therefore, the temperature acquisition unit 55 acquires the temperature of the injector 19 through the temperature sensor 21 from the viewpoint of protecting the injector 19 including the coil 36. In this case, the temperature acquisition unit 55 not only directly acquires the temperature of the coil 36 through the temperature sensor 21 as in the present embodiment, but also indirectly obtains the temperature of the coil 36 from, for example, the energization timing of the coil 36 and the accumulated value of the energization amount. The temperature of the coil 36 may be estimated.

The injection control unit 51 raises the target current value I1 to the target current value I2 when the temperature of the injector 19 acquired by the temperature acquisition unit 55, specifically, the temperature of the coil 36 is equal to or lower than the set temperature Td. That is, as described above, the coil 36 of the injector 19 is susceptible to temperature. On the other hand, when the target current value I2 is raised, a larger current flows through the coil 36, and the calorific value increases. Therefore, the injection control unit 51 acquires the temperature of the coil 36 through the temperature acquisition unit 55, and raises the temperature to the target current value I2 on condition that the temperature is equal to or lower than the set temperature Td. The set temperature Td is arbitrarily set according to the performance of the injector 19.

The electronic control device 50 is connected to the notification unit 56. The notification unit 56 notifies the abnormality of the vehicle including the exhaust gas purification system 10. The notification unit 56 notifies an abnormality through hearing such as a buzzer or chime, or through vision such as a lamp or an indicator. It should be noted that these notification units 56 are examples, and any configuration can be adopted as long as the configuration is such that an abnormality is notified through the five senses.

Hereinafter, the processing flow of the electronic control device 50 according to the above configuration will be described with reference to FIGS. 6 to 8.
When the exhaust gas purification system 10 is started (S101), the injection control unit 51 and the determination unit 53 determine whether or not the stop signal of the exhaust gas purification system 10 is "on" (S102). When the injection control unit 51 and the determination unit 53 determine that the stop signal is "on" in S102 (S102: Yes), the exhaust gas purification system 10 is stopped (S103), and the process is completed. On the other hand, when the injection control unit 51 and the determination unit 53 determine that the stop signal is not "on" in S102 (S102: No), the upper limit of the current supplied to the injector 19 is set to the target current value I1 (S104). ). Then, the injection control unit 51 injects urea water through the injector 19 (S105). The injection control unit 51 sets the amount of urea water to be added to the exhaust gas based on the operating state of the internal combustion engine 11. The injection control unit 51 drives the injector 19 based on the set amount of urea water. As a result, the injector 19 injects the amount of urea water set by the injection control unit 51 into the exhaust gas flowing through the exhaust pipe.

The current acquisition unit 52 acquires the current supplied to the injector 19 as an output current value when the injection of urea water is being carried out from the injector 19 in S105 (S106). That is, the current acquisition unit 52 acquires the current flowing through the coil 36 when the drive signal is output from the injection control unit 51 to the injector 19, and uses this as the output current value. The determination unit 53 detects the current gradient value from the output current value acquired in S106 (S107). That is, the determination unit 53 acquires the output current value every few microseconds, and detects the amount of change in the output current value that changes with time as the current gradient value. Here, the period for detecting the current detection value is a period until the output current value reaches the target current value.

The determination unit 53 determines whether or not the current gradient value detected in S107 is “0” (S108). When the determination unit 53 determines that the current gradient value is "0" (S108: Yes), the determination unit 53 defines the output current value at this time as the specific current value Id (S109). Then, the determination unit 53 determines whether or not the specific current value Id defined in S109 is equal to or higher than the preset set value S4 (S110).

When the elimination control unit 54 determines in S110 that the specific current value is the set value S4 or more (S110: Yes), the elimination control unit 54 shifts to the elimination control (S111). When the elimination control unit 54 shifts to the elimination control, the pressure of the urea water is increased (S112). That is, the elimination control unit 54 increases the elimination pressure P1 discharged from the urea water pump 15 to a elimination pressure P1 higher than the normal pressure Pn by increasing the rotation speed of the urea water pump 15. As a result, the exhaust gas purification system 10 shifts from the normal control state to the sticking elimination control state. Then, the injector 19 is supplied with urea water having a release pressure P1 to eliminate the sticking. On the other hand, when the cancellation control unit 54 determines in S110 that the specific current value is less than the set value S4 (S110: No), it returns to S102 and continues the process of shifting to S102. That is, when the specific current value is less than the set value S4 in S110, the injector 19 is not stuck. Therefore, the electronic control device 50 maintains the exhaust gas purification system 10 in the normal control state.

When the pressure of the urea water is increased in S112, the injection control unit 51 and the determination unit 53 determine whether or not the stop signal of the exhaust purification system 10 is "on" (S113). When the injection control unit 51 and the determination unit 53 determine that the stop signal is not "on" in S113 (S113: No), the injection control unit 51 and the determination unit 53 inject urea water through the injector 19 (S114). That is, since the pressure of the urea water is increased in S112, the injection control unit 51 injects the urea water by the elimination pressure P1. On the other hand, when the injection control unit 51 and the determination unit 53 determine that the stop signal is "on" in S113 (S113: Yes), the injection control unit 51 and the determination unit 53 shift to S103 and stop the exhaust gas purification system 10.

The current acquisition unit 52 acquires the current supplied to the injector 19 as an output current value when the injection of urea water is being carried out from the injector 19 in S114 (S115). The determination unit 53 detects the current gradient value from the output current value acquired in S115 (S116). The determination unit 53 determines whether or not the current gradient value detected in S116 is “0” (S117). When the determination unit 53 determines that the current gradient value is "0" (S117: Yes), the determination unit 53 defines the output current value at this time as the specific current value Id (S118). Then, the determination unit 53 determines whether or not the specific current value Id defined in S118 is equal to or higher than the preset set value S2 (S119).

When the temperature acquisition unit 55 determines in S119 that the specific current value Id is the set value S2 or more (S119: Yes), the temperature acquisition unit 55 acquires the temperature of the injector 19 (S120). Further, when the temperature acquisition unit 55 determines in S117 that the current gradient value is not "0" (S117: No), the temperature acquisition unit 55 acquires the temperature of the injector 19 in S120. The injection control unit 51 determines whether or not the temperature of the injector 19 acquired in S120 is equal to or lower than the set temperature Td (S121). Then, when the injection control unit 51 determines in S121 that the temperature of the injector 19 is equal to or lower than the set temperature Td (S121: Yes), the upper limit of the current supplied to the injector 19 is raised from the target current value I1 to the target current value I2. (S122). That is, the electronic control device 50 shifts the operating state of the exhaust gas purification system 10 from the sticking elimination control state to the valve opening force increase control state. On the other hand, when the injection control unit 51 determines in S121 that the temperature of the injector 19 is higher than the set temperature Td (S121: No), the injection control unit 51 returns to S113 and continues the process of shifting to S113. That is, when the temperature of the injector 19 is higher than the set temperature Td in S121, the injector 19 has a large thermal load. Therefore, the electronic control device 50 continues the process without shifting to the valve opening force increase control state.

When the target current value I2 is set in S122, the injection control unit 51 and the determination unit 53 determine whether or not the stop signal of the exhaust gas purification system 10 is “on” (S123). When the injection control unit 51 and the determination unit 53 determine that the stop signal is not "on" in S123 (S123: No), the injection control unit 51 and the determination unit 53 acquire the temperature of the injector 19 from the temperature acquisition unit 55 (S124). On the other hand, when the injection control unit 51 and the determination unit 53 determine that the stop signal is "on" in S123 (S123: Yes), the injection control unit 51 and the determination unit 53 shift to S103 and stop the exhaust gas purification system 10.

The injection control unit 51 determines whether or not the temperature of the injector 19 acquired in S124 is equal to or lower than the set temperature Td (S125). Then, when the injection control unit 51 determines in S125 that the temperature of the injector 19 is equal to or lower than the set temperature Td (S125: Yes), the injection control unit 51 injects urea water (S126). That is, since the injector 19 has a set temperature Td or less, the upper limit of the supplied current is raised to the target current value I2, and then the urea water is injected.

The current acquisition unit 52 acquires the current supplied to the injector 19 as an output current value when the injection of urea water is being carried out from the injector 19 in S126 (S127). The determination unit 53 detects the current gradient value from the output current value acquired in S127 (S128). The determination unit 53 determines whether or not the current gradient value detected in S128 is “0” (S129). When the determination unit 53 determines that the current gradient value is "0" (S129: Yes), the determination unit 53 defines the output current value at this time as the specific current value Id (S130). Then, the determination unit 53 determines whether or not the specific current value Id defined in S130 is equal to or higher than the preset set value S1 (S131). On the other hand, if the determination unit 53 determines in S129 that the current gradient value is not "0" (S129: No), the determination unit 53 returns to S123 and continues the process of shifting to S123. That is, when the current gradient value is not "0", it is considered that the output current value is changing. Therefore, the determination unit 53 continues the process of shifting to S123 until the current gradient value becomes “0”.

When the determination unit 53 determines in S131 that the specific current value Id is the set value S1 or more (S131: Yes), the urea is preset a predetermined number of times after the target current value is set to the target current value I2 in S122. It is determined whether or not the water has been sprayed (S132). That is, the determination unit 53 determines whether or not the number of times of injecting urea water from the injector 19 has reached a predetermined number of times after the target current value I2 is set. In this case, the predetermined number of times can be arbitrarily set according to the performance of the exhaust gas purification system 10. When the determination unit 53 determines that the injection has been performed a predetermined number of times in S132 (S132: Yes), the determination unit 53 executes the notification process (S133). That is, the determination unit 53 notifies through the notification unit 56 that the sticking of the injector 19 may not be resolved and the injection of urea water may be hindered. Then, the determination unit 53 shifts to S103 and stops the exhaust gas purification system 10.

Driving the injector 19 with the target current value I2 set in S122 increases the load applied to the injector 19. Therefore, if the driving with the target current value I2 is continued even though the number of injections of urea water has reached a predetermined number of times, the load of the injector 19 may exceed the permissible amount. Therefore, the determination unit 53 stops the exhaust gas purification system 10 after notifying the possibility of sticking of the injector 19 when the injection of urea water by the target current value I2 has reached a predetermined number of times. As a result, it is possible to avoid an excessive load applied to the injector 19. On the other hand, when the determination unit 53 determines that the injection has not been performed a predetermined number of times in S132 (S132: No), the determination unit 53 returns to S123 and continues the process of shifting to S123. That is, the injection control unit 51 and the determination unit 53 determine that when the urea water has not been injected a predetermined number of times, the urea water can be continuously injected until the set temperature Td is reached.

By the way, when it is determined in S108 that the current gradient value detected in S107 is not "0" (S108: No), the temperature acquisition unit 55 acquires the temperature of the injector 19 (S134). The injection control unit 51 determines whether or not the temperature of the injector 19 acquired in S134 is equal to or lower than the set temperature Td (S135). That is, when it is determined in S107 that the current gradient value is not "0", it is expected that the current flowing through the coil 36 continues to increase due to the sticking of the injector 19. Therefore, the injection control unit 51 determines whether or not the temperature of the injector 19 is equal to or less than the set temperature Td. Then, when the injection control unit 51 determines in S135 that the temperature of the injector 19 is equal to or lower than the set temperature Td (S135: Yes), the injection control unit 51 shifts to S122 and raises the upper limit of the current supplied to the injector 19 to the target current value I2. .. That is, the electronic control device 50 shifts the operating state of the exhaust gas purification system 10 from the normal control state to the valve opening force increase control state. On the other hand, when the injection control unit 51 determines in S135 that the temperature of the injector 19 is higher than the set temperature Td (S135: No), the injection control unit 51 shifts to S112 and increases the pressure of the urea water. That is, when the temperature of the injector 19 is higher than the set temperature Td, the current supplied to the coil 36 of the injector 19 cannot be increased. Therefore, the injection control unit 51 shifts to S112, and the elimination control unit 54 executes elimination control for increasing the pressure of the urea water discharged from the urea water pump 15.

Further, when the determination unit 53 determines in S119 that the specific current value Id specified in S118 is not the set value S2 or more, that is, is less than the set value S2 (S119: No), the specific current value Id defined in S118 is determined. It is determined whether or not the set value is S5 or more (S136). Then, when the elimination control unit 54 determines in S136 that the specific current value Id is less than the set value S5 (S136: No), the pressure of the urea water increased in S112 is restored to the normal pressure Pn (S). S137). That is, the elimination control unit 54 controls the rotation speed of the urea water pump 15 and the like to set the urea water discharged from the urea water pump 15 to the normal pressure Pn. As a result, the exhaust gas purification system 10 shifts from the sticking elimination control state to the normal control state. That is, the exhaust gas purification system 10 returns to the normal control state. As described above, when the specific current value Id is determined to be less than the set value S5 in S136, it is considered that the injector 19 is eliminated from sticking by the elimination control in which the pressure of the urea water is set to the elimination pressure P1. Therefore, the elimination control unit 54 returns the operating state of the urea water pump 15 to the normal state. After shifting to the normal control state, the cancellation control unit 54 returns to S102 and continues the process of shifting to S102.

On the other hand, when it is determined in S136 that the specific current value is equal to or higher than the set value S5 (S136: Yes), the elimination control unit 54 returns to S113 and continues the process of shifting to S113. That is, when the specific current value Id specified in S118 is the set value S5 or more, it is considered that the sticking of the injector 19 is not eliminated by the elimination control. Therefore, the elimination control unit 54 continues the elimination control in which the pressure of the urea water discharged from the urea water pump 15 is set to the elimination pressure P1.

When the determination unit 53 determines in S131 that the specific current value Id specified in S130 is less than the set value S1 (S131: No), the specific current value Id specified in S130 is the preset value S3 or more. Whether or not it is determined (S138). Then, when the injection control unit 51 determines in S138 that the specific current value Id is less than the set value S3 (S138: No), the injection control unit 51 sets the target current value I2 set in S122 to the target current value I1 (S139). ). That is, the injection control unit 51 returns the target value of the current supplied to the injector 19 from the target current value I2 to the target current value I1. Then, the injection control unit 51 returns to S113. As a result, the exhaust gas purification system 10 shifts from the valve opening force increase control state to the sticking elimination control state. When it is determined in S138 that the specific current value Id is less than the set value S3, it is considered that the injector 19 is eliminated from the sticking due to the increase in the driving force accompanying the increase in the supplied current. Therefore, the injection control unit 51 returns the operating state of the injector 19 to the normal state where the target current value I1 is set. On the other hand, when the injection control unit 51 determines in S138 that the specific current value Id is the set value S3 or more (S138: Yes), the injection control unit 51 returns to S123 and continues the process of shifting to S123. That is, when the specific current value Id is the set value S3 or more, it is considered that the sticking of the injector 19 is not eliminated. Therefore, the injection control unit 51 continues the valve opening force increase control state by increasing the driving force with the current supplied to the injector 19 as the target current value I2.

In one embodiment described above, the current acquisition unit 52 acquires the current supplied to the injector 19 as an output current value. Then, the determination unit 53 determines whether or not the injector 19 is fixed by using the output current value acquired by the current acquisition unit 52. The output current value changes depending on the operating state of the injector 19. The determination unit 53 determines whether or not the injector 19 is operating normally, that is, whether or not the injector 19 is stuck by acquiring the tendency of the output current value to change with time. Further, the output current value is acquired during the operation of the exhaust gas purification system 10 as in the operation of the injector 19. Therefore, the output current value is acquired regardless of a specific time such as when the exhaust gas purification system 10 is stopped. Therefore, regardless of the timing, it is possible to determine the sticking of the injector 19 even during the operation of the exhaust gas purification system 10.

Further, in one embodiment, the determination unit 53 sets the specific current value Id and the set values S1, S2, S3, S4, S5 in which the current gradient value, which is the amount of change over time of the output current value, is “0”. Contrast. Then, when the specific current value Id is set value S1, S2, S3, S4, S5 or more, the determination unit 53 determines the sticking of the injector 19 for each condition. The current flowing through the coil 36 of the injector 19 has a current gradient value of "0" when the injector 19 opens. Then, when the injector 19 is considered to be stuck, the current flowing through the coil 36 becomes large when the injector 19 opens, and the specific current value Id becomes large. Therefore, by comparing the specific current value Id at which the current gradient value is "0" with the set values S1, S2, S3, S4, and S5, control including presence / absence of sticking of the injector 19 and elimination of sticking is performed. The state of is determined. Therefore, the sticking of the injector 19 can be determined by using the output current value acquired during the operation of the exhaust gas purification system 10.

In one embodiment, when the determination unit 53 determines that the injector 19 is stuck, the elimination control for increasing the pressure of the urea water is executed in order to eliminate the adhesion. As a result, when the injector 19 is considered to be stuck, urea water having a cancellation pressure P1 higher than the normal pressure Pn is supplied to the injector 19. As a result, the precipitate that causes the injector 19 to stick is promoted to be removed by the high-pressure urea water. Therefore, even if the injector 19 is stuck, the sticking can be eliminated and the injection of urea water can be continued.

In one embodiment, the injection control unit 51 acquires the temperature of the injector 19. Then, when the acquired temperature of the injector 19 is equal to or less than the set temperature Td, the injection control unit 51 increases the target value of the current supplied to the injector 19 from the target current value I1 to the target current value I2. Further, in one embodiment, when the injection control unit 51 performs elimination control by the elimination control unit 54, that is, the sticking of the injector 19 is not eliminated even if the pressure increase of the urea water is executed, the injection control unit 51 is subject to the temperature of the injector 19. The target value of the current supplied to the injector 19 is increased from the target current value I1 to the target current value I2. By raising the target value of the current from the target current value I1 to the target current value I2, a larger current is supplied to the coil 36 of the injector 19. Therefore, the force of opening the valve in the injector 19 is also increased. On the other hand, if a large amount of current is supplied to the injector 19, heat is generated in the coil 36, which causes a problem due to this heat generation. Therefore, the injection control unit 51 determines whether or not to raise the target current value I1 to the target current value I2 based on the acquired temperature of the coil 36. Therefore, it is possible to eliminate the sticking due to the increase in the driving force of the injector 19 and to protect the injector 19.

The present invention described above is not limited to the above embodiment, and can be applied to various embodiments without departing from the gist thereof.

The present disclosure has been described in accordance with the examples, but it is understood that the present disclosure is not limited to the examples and structures. The present disclosure also includes various variations and variations within a uniform range. In addition, various combinations and forms, as well as other combinations and forms that include only one element, more, or less, are within the scope and scope of the present disclosure.

In the drawing, 10 is an exhaust purification system, 11 is an internal combustion engine, 19 is an injector, 21 is a temperature sensor, 50 is an electronic control device, 51 is an injection control unit, 52 is a current acquisition unit, 53 is a judgment unit, and 54 is elimination control. Unit, 55 indicates a temperature acquisition unit.

Claims (4)

An electronic control device for an exhaust purification system (10) that injects pressurized urea water from an injector (19) into an exhaust pipe of an internal combustion engine (11) to reduce nitrogen oxides contained in the exhaust.
An injection control unit (51) that controls the current supplied to the injector (19) to control the injection of urea water from the injector (19).
A current acquisition unit (52) that acquires a current supplied from the injection control unit (51) to the injector (19) as an output current value, and a current acquisition unit (52).
Using the output current value acquired by the current acquisition unit (52), a determination unit (53) for determining whether or not the injector (19) is stuck, and a determination unit (53).
A temperature acquisition unit (55) for acquiring the temperature of the injector (19),
Equipped with
The determination unit (53) detects a current gradient value which is a change amount of the output current value over time, and sets the output current value when the detected current gradient value becomes 0 as a specific current value. When the specific current value is equal to or higher than the preset value, it is determined that the injector (19) is stuck, and the injector (19) is determined to be stuck.
The injection control unit (51) targets the current supplied to the injector (19) when the temperature of the injector (19) acquired by the temperature acquisition unit (55) is equal to or lower than a preset set temperature. An electronic control device for an exhaust purification system that increases the target current value, which is the value . A claim further comprising a elimination control unit (54) that executes elimination control for eliminating the adhesion of the injector (19) when the determination unit (53) determines that the injector (19) is stuck. Item 1. The electronic control device for the exhaust gas purification system according to Item 1. An electronic control device for an exhaust purification system (10) that injects pressurized urea water from an injector (19) into an exhaust pipe of an internal combustion engine (11) to reduce nitrogen oxides contained in the exhaust.
An injection control unit (51) that controls the current supplied to the injector (19) to control the injection of urea water from the injector (19).
A current acquisition unit (52) that acquires a current supplied from the injection control unit (51) to the injector (19) as an output current value, and a current acquisition unit (52).
Using the output current value acquired by the current acquisition unit (52), a determination unit (53) for determining whether or not the injector (19) is stuck, and a determination unit (53).
When the determination unit (53) determines that the injector (19) is stuck, the cancellation control unit (54) that executes the cancellation control for eliminating the sticking of the injector (19).
A temperature acquisition unit (55) for acquiring the temperature of the injector (19),
Equipped with
Even if the elimination control unit (54) executes the elimination control, the injection control unit (51) does not eliminate the sticking of the injector (19), and the injector acquired by the temperature acquisition unit (55). An electronic control device for an exhaust purification system that increases a target current value, which is a target value of a current supplied to the injector (19), when the temperature of (19) is equal to or lower than a preset set temperature. The determination unit (53) detects a current gradient value which is an amount of change over time of the output current value, and sets the output current value when the detected current gradient value becomes 0 as a specific current value. The electronic control device for an exhaust purification system according to claim 3, wherein when the specific current value is equal to or higher than a preset value, it is determined that the injector (19) is stuck.

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