JP5914180B2 - Abnormality detection device for reducing agent supply device and reducing agent supply device - Google Patents

Description

  The present invention relates to an abnormality detecting device for a reducing agent supply device for detecting an abnormality occurring in a reducing agent supply device for injecting a liquid reducing agent into an exhaust pipe, and a reducing agent supply including such an abnormality detecting device. It relates to the device.

Exhaust gas discharged from an internal combustion engine mounted on a vehicle or the like contains nitrogen oxides (NO _x ). As one of exhaust purifying apparatus for purifying the NO _X, supply and reducing catalyst disposed in an exhaust passage of an internal combustion engine, a liquid reducing agent in the upstream urea solution or unburned fuel in the side or the like of the reduction catalyst in an exhaust pipe There is known an exhaust emission control device provided with a reducing agent supply device. The exhaust gas purifying apparatus, in which the ammonia produced from the NO _X and the liquid reducing agent in the exhaust using a reducing catalyst efficiently by reduction to decompose NO _X to nitrogen and water.

  As one aspect of the reducing agent supply device used in such an exhaust purification device, a pump and a reducing agent injection valve are provided, the liquid reducing agent is pumped by the pump, and through a reducing agent injection valve fixed to the exhaust pipe. There is a direct injection type reducing agent supply device that supplies liquid reducing agent into an exhaust pipe.

In the reducing agent supply device, the required injection amount of the liquid reducing agent is determined according to the NO _x amount discharged from the internal combustion engine, and it is required that the required injection amount can be injected into the exhaust pipe without excess or deficiency. Therefore, the pump drive amount is set based on the supply pressure so that the pressure of the liquid reducing agent supplied to the reducing agent injection valve (hereinafter referred to as “supply pressure”) is maintained at a predetermined set pressure. There is a reducing agent supply device that adjusts the driving amount of the reducing agent injection valve while realizing feedback control to realize a desired injection amount (see Patent Document 1).

JP 2010-174786 A

  In such a reducing agent supply device, various abnormalities such as deterioration with time of the pump and leakage of the liquid reducing agent can occur. When an abnormality occurs in the reducing agent supply device, the injection amount of the liquid reducing agent varies, making it difficult to realize injection according to the required injection amount. Therefore, an attempt has been made to detect an abnormality occurring in the reducing agent supply device based on the supply pressure of the liquid reducing agent.

  However, in the reducing agent supply device that feedback-controls the pump drive amount based on the supply pressure of the liquid reducing agent, the pump drive amount follows even if some abnormality occurs in the reducing agent supply device. The supply pressure of the liquid reducing agent is maintained at a predetermined set pressure. Accordingly, there has been a problem that it is difficult to specify the cause of the abnormality of the reducing agent supply device from the diagnosis based on the supply pressure of the liquid reducing agent.

  In view of this, the inventors of the present invention diligently worked to reduce the pump in the non-injecting state of the liquid reducing agent in the reducing agent supply device in which the pump drive amount is controlled so that the supply pressure of the liquid reducing agent is maintained at the set pressure The present invention has been completed by finding that such a problem can be solved by providing an abnormality determination unit that determines the cause of an abnormality based on the driving amount. That is, an object of the present invention is to provide an abnormality detection device for a reducing agent supply device that can determine the cause of an abnormality of the reducing agent supply device, and a reducing agent supply device including such an abnormality detection device.

According to the present invention, a pump for pumping the liquid reducing agent accommodated in the tank, a reducing agent injection valve for injecting the liquid reducing agent pumped by the pump into the exhaust pipe of the internal combustion engine, A supply passage connecting the pump and the reducing agent injection valve; a return passage branched from the supply passage to return excess liquid reducing agent to the tank; a throttle passage provided in the return passage or a check A pump and a pressure detection means for detecting the pressure in the supply passage, and the pump so that the pressure of the liquid reducing agent supplied to the reducing agent injection valve is maintained at a predetermined set pressure. In the abnormality detecting device of the reducing agent supply device for detecting an abnormality occurring in the reducing agent supply device in which the driving amount of the liquid is controlled, based on the driving amount of the pump in the non-injecting state of the liquid reducing agent, Serial includes an abnormality determination unit to determine the cause of the abnormality of the reducing agent supply device, the abnormality determining unit, after the determination based on the driving amount of the pump in the non-injection state, further, the injection of the liquid reducing agent abnormality of the reducing agent supply apparatus characterized that you determine an abnormality occurring in the reducing agent supply device based drive amount of variation of the reducing agent injection valve in state on the drive amount of variation of the pump A detection device is provided to solve the above-mentioned problems.

That is, the abnormality detection device for the reducing agent supply device of the present invention includes an abnormality determination unit that determines the cause of the abnormality of the reducing agent supply device based on the driving amount of the pump in the non-injection state of the liquid reducing agent. Therefore, it is possible to determine the cause of the abnormality of the reducing agent supply device that cannot be determined by the supply pressure of the liquid reducing agent. Furthermore, even in the liquid reducing agent injection state, it is possible to determine the cause of the abnormality of the reducing agent supply device that cannot be determined by the supply pressure of the liquid reducing agent.

Further, in configuring the abnormality detection device of the reducing agent supply device of the present invention, the abnormality determination unit is configured such that the drive amount of the pump in the non-injection state is equal to or greater than a first threshold value greater than a predetermined reference value. While determining that the leakage of the liquid reducing agent is occurring at the time, the throttle passage or when the drive amount of the pump in the non-injection state is equal to or smaller than a second threshold value smaller than the reference value It is preferable to determine that the check valve is blocked.
By determining the cause of the abnormality of the reducing agent supply device in this way, in the state where there is no injection of the liquid reducing agent from the reducing agent injection valve and the driving amount of the pump should be the reference value, the driving of the pump with respect to the reference value The magnitude of the amount can be seen, and the leakage of the liquid reducing agent and the blockage of the throttle passage or the check valve in the return passage can be discriminated.

Further, in configuring the abnormality detection device for the reducing agent supply device of the present invention, the abnormality determination unit further includes a drive amount of the pump in the non-injection state that is greater than the reference value and greater than the first threshold value. It is preferable to determine that the deterioration of the pump with time is occurring when the value is equal to or larger than the third threshold value of a small value and smaller than the first threshold value.
By determining the cause of the abnormality of the reducing agent supply device in this way, in the state where there is no injection of the liquid reducing agent from the reducing agent injection valve and the driving amount of the pump should be the reference value, the leakage of the liquid reducing agent In addition to the restriction of the throttle passage or the check valve in the return passage, the deterioration of the pump over time can be further determined.

Further, in configuring the abnormality detection device for the reducing agent supply device of the present invention, the abnormality determination unit reads the drive amount of the pump stored in the non-injection state, and performs the first threshold value and the second threshold value. It is preferable to perform the determination by comparing with a threshold value and the third threshold value.
By determining the cause of the abnormality of the reducing agent supply device in this way, in the non-injecting state of the liquid reducing agent, the leakage of the liquid reducing agent, the blockage of the throttle passage or the check valve in the return passage, It becomes possible to discriminate deterioration.

Further, in configuring the abnormality detecting device of the reducing agent supply device of the present invention, the abnormality determining unit is configured to calculate a change amount of the driving amount of the reducing agent injection valve and a change amount of the pump driving amount in the injection state. While it is determined that the reducing agent injection valve is closed when the ratio is equal to or less than a predetermined fifth threshold, the amount of change in the driving amount of the reducing agent injection valve and the driving amount of the pump in the injection state are determined. It is preferable to determine that the liquid reducing agent has leaked when the ratio to the change amount is equal to or greater than a predetermined fourth threshold value.
By determining the cause of the abnormality of the reducing agent supply device in this way, in the liquid reducing agent injection state, the drive amount of the pump changes in accordance with the change in the injection amount of the liquid reducing agent from the reducing agent injection valve. Whether or not the reducing agent injection valve is blocked and leakage of the liquid reducing agent can be discriminated based on whether or not they are present.

Further, in configuring the abnormality detecting device of the reducing agent supply device of the present invention, the abnormality determining unit stores the drive amount of the pump stored in the no-injection state and the time stored in the injection state at a certain time. The driving amount of the reducing agent injection valve and the driving amount of the pump are read, the difference between the driving amount of the pump stored in the injection state and the driving amount of the pump stored in the non-injection state, and It is preferable to perform the determination based on a ratio of the driving amount of the reducing agent injection valve stored in the injection state.
By determining the cause of the abnormality of the reducing agent supply device in this way, it is possible to determine the leakage of the liquid reducing agent and the blocking of the reducing agent injection valve in the liquid reducing agent injection state.

Further, in configuring the abnormality detection device for the reducing agent supply device of the present invention, the abnormality determination unit comprehensively evaluates the determination result in the non-injection state and the determination result in the injection state. Then, it is preferable to determine the cause of the abnormality of the reducing agent supply device.
By determining the cause of the abnormality of the reducing agent supply device in this way, the cause of the abnormality can be determined more specifically.

According to another aspect of the present invention, there is provided a pump for pumping a liquid reducing agent accommodated in a tank, and a reducing agent for injecting the liquid reducing agent pumped by the pump into an exhaust pipe of an internal combustion engine. An injection valve, a supply passage connecting the pump and the reducing agent injection valve, a return passage branched from the supply passage to return excess liquid reducing agent to the tank, and a throttle provided in the return passage includes a passageway or check valve, a pressure detecting means for detecting the pressure of the supply passage, and a electronic control unit for controlling the driving of the pump and the reducing agent injection valve, the reducing agent injection in the reducing agent supply apparatus driving amount of the pump is controlled such that the pressure of the liquid reducing agent supplied to the valve is maintained at a predetermined set pressure, the electronic control unit, the liquid reducing agent Based on the driving amount of the pump in the non-injection state, the provided an abnormality determination unit to determine the cause of the abnormality of the reducing agent supply device, the abnormality determining unit, based on the driving amount of the pump in the non-injection state determination Further, the abnormality occurring in the reducing agent supply device is determined based on the amount of change in the driving amount of the reducing agent injection valve and the amount of change in the driving amount of the pump in the liquid reducing agent injection state. a reducing agent supply device according to claim to Rukoto.

That is, the reducing agent supply apparatus of the present invention includes an electronic control unit having an abnormality determination unit that determines the cause of the abnormality of the reducing agent supply apparatus based on the drive amount of the pump in the non-injecting state of the liquid reducing agent. Therefore, it is possible to determine the cause of the abnormality of the reducing agent supply apparatus that cannot be determined by the supply pressure of the liquid reducing agent. Furthermore, even in the liquid reducing agent injection state, it is possible to determine the cause of the abnormality of the reducing agent supply device that cannot be determined by the supply pressure of the liquid reducing agent.

1 is an overall view showing a configuration example of an exhaust emission control device provided with an abnormality detection device and a reducing agent supply device of a reducing agent supply device according to an embodiment of the present invention. It is a block diagram which shows the structural example of the electronic control unit as an abnormality detection apparatus of the reducing agent supply apparatus which concerns on embodiment of this invention. It is a flowchart for demonstrating abnormality determination (1st abnormality determination) concerning 1st Embodiment. It is a figure shown in order to demonstrate how to isolate | separate the cause of abnormality in 1st Embodiment. It is a figure shown in order to demonstrate the 2nd abnormality determination. It is a figure shown in order to demonstrate how to isolate the cause of abnormality in a 2nd embodiment. It is a flowchart for demonstrating the abnormality determination concerning 2nd Embodiment. It is a flowchart figure for demonstrating 2nd abnormality determination. It is a figure shown in order to demonstrate how to isolate the cause of abnormality in the second abnormality determination.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments relating to an abnormality detecting device for a reducing agent supply device and a reducing agent supply device according to the present invention will be specifically described below with reference to the drawings.
In addition, in each figure, about the thing which attached | subjected the same code | symbol, the same member is shown unless there is particular description, and description is abbreviate | omitted suitably.

[First Embodiment]
1. FIG. 1 is an exhaust diagram provided with a reducing agent supply device abnormality detection device (electronic control unit: ECU) 40 and a reducing agent supply device 20 according to a first embodiment of the present invention. It is a figure shown in order to demonstrate an example of the whole structure of the purification apparatus.
Exhaust purification apparatus 10 is an apparatus for purifying NO _X in the exhaust gas, is provided in the exhaust passage 11 of an internal combustion engine such as a diesel engine (not shown). The exhaust purification device 10 includes a reduction catalyst 13 interposed in the middle of the exhaust passage 11 and a reducing agent supply device 20 for supplying a liquid reducing agent into the exhaust passage 11 upstream of the reduction catalyst 13. ing.

The reduction catalyst 13 is a catalyst having a function of promoting the decomposition of NO _{x in} the exhaust, adsorbs the reducing component generated from the liquid reducing agent, and selectively reduces the NO _x in the exhaust flowing into the catalyst by the reducing component. It is a catalyst that reduces to The reducing agent supply apparatus 20 of the present embodiment uses a urea aqueous solution as a liquid reducing agent, and ammonia as a reducing component is generated when the urea aqueous solution is decomposed.

2. In FIG. 1, a reducing agent supply device 20 includes a tank 21 in which a liquid reducing agent is accommodated, a pump unit 30 that pumps the liquid reducing agent, and a reducing agent that injects the liquid reducing agent into the exhaust passage 11. A reducing agent injection valve 25 is provided as an injection unit. The pump unit 30 includes a pump 23 and a flow path switching valve 33. The reducing agent injection valve 25, the pump 23, and the flow path switching valve 33 are controlled by the ECU 40.

  The pump 23 and the tank 21 are connected by a first supply passage 27, and the pump 23 and the reducing agent injection valve 25 are connected by a second supply passage 28. Among these, the second supply passage 28 has a pressure sensor as pressure detection means for detecting the pressure in the second supply passage 28, that is, the pressure of the liquid reducing agent pumped to the reducing agent injection valve 25. 31 is provided. The pump 23 is connected to the first supply passage 27 and the second supply passage 28 via a flow path switching valve 33. The end of the first supply passage 27 on the tank 21 side is located in the vicinity of the bottom surface of the tank 21 so that the liquid reducing agent can be sucked up.

  In the flow path switching valve 33, the flow direction of the liquid reducing agent pumped by the pump 23 flows in the forward direction flowing from the tank 21 side to the reducing agent injection valve 25 side, and the reverse direction flowing from the reducing agent injection valve 25 side to the tank 21 side. It has a function to switch between directions. In the reducing agent supply apparatus 20 according to the present embodiment, the flow path switching valve 33 communicates the first supply passage 27 with the inlet side 23a of the pump 23 in a non-energized state and the second supply passage 28 with the pump 23. The first supply passage 27 is in communication with the outlet side 23b of the pump 23 and the second supply passage 28 is in communication with the inlet side 23a of the pump 23. Yes.

  That is, in the operating state of the internal combustion engine, the flow path switching valve 33 is not energized in order to supply the liquid reducing agent to the reducing agent injection valve 25 side. On the other hand, when the internal combustion engine is stopped, the flow path switching valve 33 is energized in order to collect the liquid reducing agent in the reducing agent supply device 20 in the tank 21.

  The configuration in which the liquid reducing agent can be collected in the tank 21 when the internal combustion engine is stopped is not limited to the example in which the flow path switching valve 33 is provided. For example, the liquid reducing agent can be collected by using the pump 23 that can rotate in reverse.

In addition, a return passage 29 having the other end connected to the tank 21 is branched in the middle of the second supply passage 28. An end of the return passage 29 on the tank 21 side is connected to a gas phase portion in the tank 21.
The tank 21 is provided with an air blizzard or the like, and is configured so that the internal pressure is maintained at atmospheric pressure.

  In the middle of the return passage 29, a throttle passage 37 having a reduced flow passage area is provided so that the pressure in the second supply passage 28 can be increased. The return passage 29 on the second supply passage 28 side of the throttle passage 37 is provided with a check valve 35 for preventing the liquid reducing agent from flowing from the tank 21 side to the second supply passage 28 side. It has been. However, either one of the throttle passage 37 or the check valve 35 may be omitted.

  In the reducing agent supply device 20 according to the present embodiment, the pressure sensor 31 is provided in the pump unit 30, but may be provided at any position in the second supply passage 28.

  The pump 23 pumps a liquid reducing agent at a predetermined flow rate by energization control by the ECU 40. In the present embodiment, the pump 23 is an electromagnetic pump, and the output (discharge amount) of the pump 23 increases as the drive duty ratio Duty_P increases. The drive duty ratio Duty_P of the pump 23 means a ratio of energization time during a predetermined cycle period. In the pump 23 of the present embodiment, the drive duty ratio indicates the drive amount in the present invention.

  During the injection control of the liquid reducing agent, the pressure value (supply pressure) Pu in the second supply passage 28 detected by the pressure sensor 31 is maintained at a predetermined set pressure Pu_tgt set in advance. The drive duty ratio Duty_P of the pump 23 is feedback controlled. Specifically, the ECU 40 detects the pressure by the pressure sensor 31 provided in the second supply passage 28 while circulating the liquid reducing agent pumped to the second supply passage 28 to the tank 21 through the return passage 29. The drive duty ratio Duty_P of the pump 23 is PID-controlled based on a difference ΔPu between the supplied supply pressure Pu and a preset pressure Pu_tgt set in advance. Further, when the liquid reducing agent is collected in the tank 21, the ECU 40 controls the pump 23 with a predetermined drive duty ratio Duty_P, for example.

  The reducing agent injection valve 25 is controlled to open and close by energization control, and injects a predetermined amount of liquid reducing agent into the exhaust passage 11. In the present embodiment, the reducing agent injection valve 25 is an electromagnetic on / off valve that closes in a non-energized state and opens in an energized state. The ECU 40 obtains the required injection amount Qdv_tgt based on a predetermined arithmetic expression and assumes that the supply pressure Pu in the second supply passage 28 is the set pressure Pu_tgt for each predetermined injection cycle. Then, the drive duty ratio Duty_V corresponding to the required injection amount Qdv_tgt is determined, and energization control of the reducing agent injection valve 25 is performed. The drive duty ratio Duty_V of the reducing agent injection valve 25 means a ratio of energization time in one injection cycle.

3. Electronic control unit (abnormality detection device)
FIG. 2 shows a configuration example in which functional blocks are used to represent portions related to the control of the reducing agent supply device 20 and the abnormality detection of the reducing agent injection device 20 in the ECU 40 of the present embodiment. The ECU 40 has not only a function as a control device of the reducing agent supply device 20 but also a function as an abnormality detection device of the reducing agent injection device 20 according to the present invention.

  The ECU 40 is configured around a known microcomputer, and includes a pump drive control unit 41, a reducing agent injection valve drive control unit 43, and an abnormality determination unit 45. Specifically, each of these units is realized by executing a program by a microcomputer.

  In addition to this, the ECU 40 is shown for energizing a memory element (not shown) such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and the pump 23, the flow path switching valve 33, and the reducing agent injection valve 25. The drive circuit etc. which are not provided are provided. The ECU 40 receives sensor values of various sensors provided in the reducing agent supply device 20, the internal combustion engine, the exhaust passage 11, and the like, in addition to the sensor value of the pressure sensor 31, and based on the sensor values. Values such as the supply pressure Pu obtained are stored in the storage element.

  The pump drive control unit 41 pumps the supply pressure Pu in the second supply passage 28 to be maintained at the set pressure Pu_tgt based on the supply pressure Pu detected by the pressure sensor 31 during operation of the internal combustion engine. 23, feedback control of the output is performed. Specifically, when the supply pressure Pu is higher than the set pressure Pu_tgt, the drive duty ratio Duty_P is reduced, and when the supply pressure Pu is lower than the set pressure Pu_tgt, the drive duty ratio Duty_P is increased. The pump drive control unit 41 outputs a control signal corresponding to the calculated drive duty ratio Duty_P to the drive circuit of the pump 23.

Information reducing agent injection valve drive control unit 43, during operation of the internal combustion engine, exhaust gas temperature Tgas, the temperature Tcat of the reduction catalyst 13, NO _X concentration Nnox on the downstream side of the reduction catalyst 13, further relates to the rotation speed Ne of the internal combustion engine Based on the above, the required injection amount Qdv_tgt of the liquid reducing agent is calculated. Further, the reducing agent injection valve drive control unit 43 obtains the drive duty ratio Duty_V of the reducing agent injection valve 25 based on the calculated required injection amount Qdv_tgt, and outputs a control signal to the drive circuit of the reducing agent injection valve 25. To do.

  The abnormality determination unit 45 performs the first abnormality determination in the non-injecting state of the liquid reducing agent. In the present embodiment, in the first abnormality determination, the values of the drive duty ratio Duty_P1 of the pump 23 in the non-injection state of the liquid reducing agent are set to the first threshold value Thre1, the second threshold value Thre2, and the third threshold value Thre3. The cause of the abnormality is determined in comparison with. In the first abnormality determination, the leakage of the liquid reducing agent from the reducing agent injection valve 25, the blockage of the throttle passage 37 or the check valve 35 provided in the return passage 29, or the deterioration with time of the pump 23 is determined. It is configured.

  For example, the pump 23 in the case where there is no abnormality in the reducing agent supply device 20 in the state where the liquid reducing agent is not injected, that is, in the state where the total amount of the liquid reducing agent pumped by the pump 23 returns to the tank 21 via the return passage 29. Assuming that the drive duty ratio Duty_P is the reference value Duty_P0, when the liquid reducing agent leaks, the pump 23 pumps the liquid reducing agent for the amount of leakage to maintain the supply pressure Pu at the set pressure Pu_tgt. There is a need. That is, the driving duty ratio Duty_P1 of the pump 23 at this time becomes larger than the reference value Duty_P0.

  Further, when the throttle passage 37 and the check valve 35 are closed, the flow rate of the liquid reducing agent returning to the tank 21 via the return passage 29 is reduced, so that the pump 23 is in the non-injecting state of the liquid reducing agent. Drive duty ratio Duty_P1 is smaller than the reference value Duty_P0.

  Furthermore, when the pump 23 deteriorates with time, the discharge amount gradually decreases even if the control is performed with the same drive duty ratio Duty_P. In this case, in order to maintain the supply pressure Pu at the set pressure Pu_tgt in the non-injection state of the liquid reducing agent, the drive duty ratio Duty_P does not change as much as when the liquid reducing agent leaks. The drive duty ratio Duty_P1 needs to be larger than the reference value Duty_P0.

  In order to discriminate these abnormalities, a first threshold value Thre1 having a value larger than the reference value Duty_P0, a second threshold value Thre2 having a value smaller than the reference value Duty_P0, and a value larger than the reference value Duty_P0, The abnormality determination unit 45 compares the drive duty ratio Duty_P1 with the first threshold value Thre1, the second threshold value Thre2, and the third threshold value Thre3. Therefore, the existence of an abnormality and the cause of the abnormality are determined.

  Specifically, when the drive duty ratio Duty_P1 of the pump 23 in the non-injection state is equal to or greater than the first threshold Thre1, it is assumed that the liquid reducing agent has leaked, and the drive duty ratio Duty_P1 is the second threshold Thre2. In the following cases, it is assumed that the throttle passage 37 or the check valve 35 is closed. If the drive duty ratio Duty_P1 is equal to or larger than the third threshold Thre3 and smaller than the first threshold Thre1, the pump 23 It is determined that deterioration with time has occurred.

  The values of the first threshold Thre1, the second threshold Thre2, and the third threshold Thre3 are optimum values in consideration of the type and state of each component, the set pressure Pu_tgt of the liquid reducing agent, the allowable range of abnormality, and the like. Can be set as appropriate.

4). Reducing Agent Supply Device Abnormality Determination Method Hereinafter, an example of a specific flow of the reducing agent supply device 20 abnormality determination method executed by the ECU 40 according to the first embodiment will be described with reference to the flowchart of FIG. 3. .
Note that the following flowchart is executed at all times or every predetermined period during the liquid reductant injection control.

  First, in step S1, the ECU 40 determines whether or not the reducing agent supply device 20 is in a liquid reducing agent non-injection state. The non-injection state of the liquid reducing agent can be determined by determining whether the required injection amount is zero, whether the drive duty ratio Duty_V of the reducing agent injection valve 25 is zero, or the like. Step S1 is repeated until it is determined that the liquid reducing agent is in the non-injection state (Yes determination).

  If it is determined that the liquid reducing agent is not being injected, the ECU 40 proceeds to step S2 and determines whether or not the supply pressure Pu of the liquid reducing agent is stable at the set pressure Pu_tgt. For example, when the supply pressure Pu is close to the set pressure Pu_tgt for a predetermined time, it can be determined that the supply pressure Pu is stable at the set pressure Pu_tgt. If the supply pressure Pu is not stable at the set pressure Pu_tgt despite the absence of the liquid reducing agent injection state (No determination), this routine is temporarily executed because the first abnormality determination cannot be executed. Exit.

  On the other hand, when the supply pressure Pu is stable at the set pressure Pu_tgt in the non-injection state of the liquid reducing agent (Yes determination), the process proceeds to step S3, and the ECU 40 reads the drive duty ratio Duty_P1 of the pump 23 at that time. . At this time, a moving average of the drive duty ratio Duty_P in a state where the supply pressure Pu is stable at the set pressure Pu_tgt may be taken as the drive duty ratio Duty_P1 in the non-injection state.

  Next, the ECU 40 proceeds to step S4, and performs abnormality determination based on the drive duty ratio Duty_P1 read in step S3. As described above, in the present embodiment, the abnormality determination is performed by comparing the drive duty ratio Duty_P1 with the first threshold value Thre1, the second threshold value Thre2, and the third threshold value Thre3.

FIG. 4 is a table summarizing how to determine the cause of the abnormality by the first abnormality determination.
The ECU 40 determines that the liquid reducing agent has leaked when the drive duty ratio Duty_P1 in the non-injection state is equal to or greater than the first threshold value Thre1. Note that only the first abnormality determination cannot identify the part where the liquid reducing agent leaks.
In addition, the ECU 40 determines that the deterioration of the pump 23 with time is occurring when the drive duty ratio Duty_P1 in the non-injection state is equal to or greater than the third threshold Thre3 and less than the first threshold Thre1.
Further, the ECU 40 determines that no abnormality has occurred in the reducing agent supply device 20 when the drive duty ratio Duty_P1 in the non-injection state exceeds the second threshold Thre2 and is less than the third threshold Thre3.
Further, the ECU 40 determines that the throttle passage 37 or the check valve 35 is closed when the drive duty ratio Duty_P1 in the non-injection state is equal to or smaller than the second threshold value Thre2.

  Returning to FIG. 3, after making the abnormality determination in step S4, the ECU 40 proceeds to step S5 and performs error processing according to the result of the abnormality determination. If no abnormality is found, this routine is terminated without doing anything. On the other hand, if the occurrence of an abnormality is found and the cause is determined, a record indicating the occurrence of the abnormality and the cause is left, and the contents of the injection control are changed according to the cause of the abnormality, An informing means for informing the engine driver or the like of the cause of the abnormality is activated.

5. Effects of Abnormality Detection Device and Reducing Agent Supply Device According to First Embodiment The abnormality detection device 40 and the reducing agent supply device 20 according to the first embodiment described above are the pump 23 in the non-injection state of the liquid reducing agent. Based on the drive duty ratio Duty_P1, the presence / absence of abnormality of the reducing agent supply device 20 and the abnormality determining unit 45 for determining the cause thereof are provided, so that the determination is made based on the change in the supply pressure Pu of the liquid reducing agent. The cause of the abnormality of the reducing agent supply device 20 that cannot be determined can be determined.

  Further, in the abnormality detection device 40 and the reducing agent supply device 20 according to the present embodiment, the abnormality determination unit 45 determines that the drive duty ratio Duty_P1 of the pump 23 in the non-injection state is a first threshold value that is larger than the reference value Duty_P0. While it is determined that the liquid reducing agent has leaked when it is equal to or greater than Thre1, the aperture is reduced when the drive duty ratio Duty_P1 of the pump 23 in the non-injection state is equal to or smaller than the second threshold Thre2 that is smaller than the reference value Duty_P0. It is determined that the passage 37 or the check valve 35 is blocked. Therefore, the leakage of the liquid reducing agent and the blockage of the throttle passage 37 or the check valve 35 can be easily determined.

  Further, in the abnormality detection device 40 and the reducing agent supply device 20 of the present embodiment, the abnormality determination unit 45 further determines that the drive duty ratio Duty_P1 of the pump 23 in the non-injection state is larger than the reference value Duty_P0. When the value is equal to or greater than the third threshold value Thre3 that is smaller than the threshold value Thre1 and smaller than the first threshold value Thre1, it is determined that deterioration with time of the pump 23 has occurred. Therefore, in addition to the leakage of the liquid reducing agent and the blockage of the throttle passage 37 or the check valve 35, the deterioration with time of the pump 23 can be easily determined.

  Further, in the abnormality detection device 40 and the reducing agent supply device 20 of the present embodiment, the abnormality determination unit 45 reads the drive duty ratio Duty_P1 of the pump 23 stored in the non-injection state, and the first threshold value Thre1, the first threshold value Thre1. The determination is made by comparing each of the second threshold Thre2 and the third threshold Thre3. Therefore, in the non-injection state of the liquid reducing agent, the leakage of the liquid reducing agent, the blocking of the throttle passage 37 or the check valve 35, and the deterioration with time of the pump 23 can be distinguished and distinguished.

[Second Embodiment]
In the abnormality detecting device of the reducing agent supply apparatus and the reducing agent supply apparatus according to the second embodiment of the present invention, the content of the abnormality determination by the abnormality determining unit of the abnormality detecting apparatus is related to the first embodiment. It is different from the case of the abnormality detection device. Specifically, the abnormality detection device according to the present embodiment executes the second abnormality determination after executing the first abnormality determination described in the first embodiment, and then performs the reducing agent supply device. It is configured to determine the cause of the abnormality that has occurred.
Hereinafter, with reference to FIG. 1 and FIG. 2, the description will focus on the abnormality determination unit 45 of the abnormality detection device (ECU) 40 according to the second embodiment, and the contents already described in the first embodiment. Are omitted as appropriate.

1. Electronic control unit (abnormality detection device)
In the second embodiment, the abnormality determination unit 45 of the ECU 40 injects the liquid reducing agent together with the first abnormality determination performed in the non-injecting state of the liquid reducing agent described in the first embodiment. The second abnormality determination performed in the state is executed. In the second abnormality determination, the cause of the abnormality is determined based on the change amount ΔDv of the drive duty ratio Duty_V of the reducing agent injection valve 25 and the change amount ΔDp of the drive duty ratio Duty_P of the pump 23 in the injection state of the liquid reducing agent. presume. Then, the abnormality determination unit 45, based on the results of the first abnormality determination and the second abnormality determination, leakage of liquid reducing agent, blocking of the reducing agent injection valve 25, blocking of the throttle passage 37 or the check valve 35, The pump 23 is configured to discriminate and determine deterioration over time.

  In the ECU 40 according to the second embodiment, as the change amount ΔDv of the drive duty ratio Duty_V of the reducing agent injection valve 25 used for the second abnormality determination, the drive duty ratio of the reducing agent injection valve 25 in the liquid reducing agent injection state. Duty_V2 (= ΔDv) is used. Further, in the ECU 40, the change amount ΔDp of the drive duty ratio Duty_P of the pump 23 used for the second abnormality determination is determined from the drive duty ratio Duty_P2 of the pump 23 at that time to the non-injection state (the drive duty ratio Duty_V1 of the reducing agent injection valve 25). = 0), the difference ΔDp obtained by subtracting the drive duty ratio Duty_P1 of the pump 23 is used.

  In the injection state of the liquid reducing agent, it is necessary to increase the discharge amount of the pump 23 in order to maintain the supply pressure Pu of the liquid reducing agent at the set pressure Pu_tgt as the liquid reducing agent is injected. At this time, for example, if there is a leakage of the liquid reducing agent, in order to maintain the supply pressure Pu of the liquid reducing agent at the set pressure Pu_tgt, the discharge amount is greater than or equal to the injection amount of the liquid reducing agent from the reducing agent injection valve 25. It is necessary to drive the pump 23. Further, when the reducing agent injection valve 25 is closed, the actual reducing agent injection amount becomes smaller than the injection amount corresponding to the drive duty ratio Duty_V of the reducing agent injection valve 25, so that the liquid reducing agent In order to maintain the supply pressure Pu at the set pressure Pu_tgt, the increase in the discharge amount of the pump 23 becomes small.

  In order to determine these abnormalities, the reference ratio between the drive duty ratio Duty_V (= ΔDv) of the liquid reducing agent and the drive duty ratio Duty_P (= ΔDp) of the pump 23 in a state where there is no abnormality in the reducing agent supply device 20. R0 (inclination ΔDp / ΔDv of the reference operating characteristic) is obtained in advance, and a fourth threshold Thre4 larger than the reference ratio R0 and a fifth threshold Thre5 smaller than the reference ratio R0 are set. Then, the abnormality determination unit 45 compares the actual ratio R1 (= ΔDp / ΔDv) with the fourth threshold Thre4 and the fifth threshold Thre5 to estimate the presence / absence of the abnormality and the cause of the abnormality. Yes.

  The values of the fourth threshold value Thre4 and the fifth threshold value Thre5 are the same as the first threshold value Thre1, the second threshold value Thre2, and the third threshold value Thre3. In consideration of Pu_tgt, the allowable range of abnormality, etc., it can be appropriately set to an optimum value.

  FIG. 5 is a diagram for explaining the concept of second abnormality determination. The horizontal axis in FIG. 5 represents the drive duty ratio Duty_V of the reducing agent injection valve 25, and the vertical axis represents the drive duty ratio Duty_P of the pump 23. In addition, the reference operation characteristic indicating the relationship between the drive duty ratio Duty_V of the reducing agent injection valve 25 and the drive duty ratio Duty_P of the pump 23 when there is no abnormality in the reducing agent supply apparatus 20 is indicated by a solid line, and the leakage of the liquid reducing agent is The operating characteristic when it occurs is indicated by a broken line, and the operating characteristic when the reducing agent injection valve 25 is blocked is indicated by an alternate long and short dash line.

When the liquid reducing agent leaks, the discharge amount of the pump 23 increases as compared with the case where there is no abnormality. Therefore, the change amount ΔDv (= Duty_V2) of the drive duty ratio Duty_V of the reducing agent injection valve 25. The ratio R1a (= ΔDpa / ΔDv) of the change amount ΔDpa (= Duty_P2a−Duty_P1a) of the drive duty ratio Duty_P of the pump 23 with respect to the difference, that is, the slope of the operation characteristic is larger than the ratio R0 of the reference operation characteristic (broken line) See).
On the other hand, when the blocking of the reducing agent injection valve 25 occurs, the discharge amount of the pump 23 is reduced compared to the case where there is no abnormality, and therefore the amount of change ΔDv of the drive duty ratio Duty_V of the reducing agent injection valve 25. The ratio R1b (= ΔDpb / ΔDv) of the change amount ΔDpb (= Duty_P2b−Duty_P1b) of the drive duty ratio Duty_P of the pump 23 with respect to (= Duty_V2), that is, the slope of the operating characteristic is smaller than the ratio R0 of the reference operating characteristic. (Refer to the single point difference line.)

  Here, since the second abnormality determination is executed in the liquid reducing agent injection state, it is possible that the liquid reducing agent has leaked due to the poor closing of the reducing agent injection valve 25. Therefore, when there is leakage of the liquid reducing agent, it can be estimated that leakage has occurred in parts other than the reducing agent injection valve 25, such as the piping and the pump 23. In other words, by considering the result of the second abnormality determination, it is possible to isolate the occurrence site when it is determined in the first abnormality determination that the liquid reducing agent has leaked. Become.

  Specifically, regarding the leakage of the liquid reducing agent, the first abnormality determination shows that the leakage of the liquid reducing agent has occurred, but cannot determine the portion where the leakage has occurred. However, in the second abnormality determination performed thereafter, if it is not determined that leakage of the liquid reducing agent from a portion other than the reducing agent injection valve 25 has occurred, the liquid due to poor closing of the reducing agent injection valve 25 It can be estimated that leakage of the reducing agent has occurred. This is because, since the reducing agent injection valve 25 is opened in the injection state, the influence of the reducing agent injection valve 25 can be ignored even if the closing failure of the reducing agent injection valve 25 occurs.

FIG. 6 is a table summarizing how to determine the cause of the abnormality of the reducing agent supply device 20 based on the results of the first abnormality determination and the second abnormality determination.
When the drive duty ratio Duty_P1 of the pump 23 is greater than or equal to the first threshold Thre1 in the first abnormality determination and the operating characteristic gradient R1 is greater than or equal to the fourth threshold Thre4 in the second abnormality determination, the ECU 40 It is determined that the liquid reducing agent has leaked from a part other than the reducing agent injection valve 25 such as the pump 23.
In addition, the ECU 40 determines that the drive duty ratio Duty_P1 of the pump 23 is greater than or equal to the first threshold Thre1 in the first abnormality determination, and the slope R1 of the operating characteristic exceeds the fifth threshold Thre5 in the second abnormality determination. If it is less than the threshold value Thre4 of 4, it is determined that leakage of the liquid reducing agent due to the abnormal closing of the reducing agent injection valve 25 has occurred.
Further, the ECU 40 determines that the drive duty ratio Duty_P1 of the pump 23 is equal to or higher than the first threshold Thre1 in the first abnormality determination and the operating characteristic gradient R1 is equal to or lower than the fifth threshold Thre5 in the second abnormality determination. It is determined that there is a sliding failure that prevents the reducing agent injection valve 25 from moving when the reducing agent injection valve 25 is open, and leakage of the liquid reducing agent has occurred.

Further, the ECU 40 determines that the drive duty ratio Duty_P1 is equal to or greater than the third threshold Thre3 and less than the first threshold Thre1 in the first abnormality determination, and the gradient R1 of the operating characteristic is the fourth threshold Thre4 in the second abnormality determination. In the above case, it is determined that the deterioration of the pump 23 with time and the leakage of the liquid reducing agent from a part other than the reducing agent injection valve 25 have occurred.
In addition, the ECU 40 determines that the drive duty ratio Duty_P1 exceeds the second threshold value Thre2 and is less than the third threshold value Thre3 in the first abnormality determination, and the slope R1 of the operating characteristic is the fifth threshold value Thre5 in the second abnormality determination. If it is greater than and less than the fourth threshold Thre4, it is determined that the deterioration of the pump 23 with time has occurred.
In addition, the ECU 40 determines that the pump duty ratio Duty_P1 is less than or equal to the second threshold Thre2 in the first abnormality determination and the operating characteristic gradient R1 is less than or equal to the fifth threshold Thre5 in the second abnormality determination. It is determined that the deterioration with time and the blocking of the reducing agent injection valve 25 have occurred.

Further, the ECU 40 determines that the drive duty ratio Duty_P1 exceeds the second threshold value Thre2 and is less than the third threshold value Thre3 in the first abnormality determination, and the slope R1 of the operating characteristic is the fourth threshold value Thre4 in the second abnormality determination. In the above case, it is determined that the liquid reducing agent leaks from a portion other than the reducing agent injection valve 25.
In addition, the ECU 40 determines that the drive duty ratio Duty_P1 exceeds the second threshold value Thre2 and is less than the third threshold value Thre3 in the first abnormality determination, and the slope R1 of the operating characteristic is the fifth threshold value Thre5 in the second abnormality determination. If it is less than the fourth threshold Thre4, it is determined that there is no abnormality in the reducing agent supply device 20.
In addition, the ECU 40 determines that the drive duty ratio Duty_P1 exceeds the second threshold value Thre2 and is less than the third threshold value Thre3 in the first abnormality determination, and the slope R1 of the operating characteristic is the fifth threshold value Thre5 in the second abnormality determination. In the following cases, it is determined that the reducing agent injection valve 25 is blocked.

In addition, the ECU 40 determines that the throttle passage 37 when the drive duty ratio Duty_P1 is equal to or smaller than the second threshold Thre2 in the first abnormality determination and the gradient R1 of the operating characteristic is equal to or larger than the fourth threshold Thre4 in the second abnormality determination. Alternatively, it is determined that the check valve 35 is blocked and the liquid reducing agent leaks from a portion other than the reducing agent injection valve 25.
In addition, the ECU 40 determines that the drive duty ratio Duty_P1 is equal to or smaller than the second threshold Thre2 in the first abnormality determination, and the slope R1 of the operating characteristic exceeds the fifth threshold Thre5 in the second abnormality determination, and the fourth threshold Thre4. If it is less, it is determined that the throttle passage 37 or the check valve 35 is closed.
In addition, the ECU 40 determines that the throttle passage 37 when the drive duty ratio Duty_P1 is equal to or smaller than the second threshold Thre2 in the first abnormality determination and the slope R1 of the operating characteristic is equal to or smaller than the fifth threshold Thre5 according to the second abnormality determination. Alternatively, it is determined that the check valve 35 is closed and the reducing agent injection valve 25 is closed.

2. Method for Determining Abnormality of Reducing Agent Supply Device Hereinafter, an example of a specific flow of an abnormality determination method for the reducing agent supply device 20 executed by the ECU 40 according to the second embodiment will be described with reference to FIGS. This will be described with reference to the flowchart. Note that the following flowchart is executed at all times or every predetermined period during the liquid reductant injection control.

The flowchart of FIG. 7 shows the main flow of the abnormality detection method executed by the ECU 40 according to the second embodiment.
First, the ECU 40 executes a first abnormality determination in step S11. The first abnormality determination can be performed in accordance with the same procedure as the content of the abnormality determination described in the first embodiment. Specifically, the steps from step S1 to step S4 in the flowchart of FIG. Execute. After executing the first abnormality determination, the ECU 40 executes the second abnormality determination in step S12.

FIG. 8 shows a specific flowchart for executing the second abnormality determination.
First, in step S21, the ECU 40 determines whether or not the drive duty ratio Duty_V of the reducing agent injection valve 25 is within a predetermined range. This is because, even when the liquid reducing agent is in the injection state, when the injection amount is small, the change amount ΔDv of the drive duty ratio Duty_V of the reducing agent injection valve 25 and the change amount ΔDp of the drive duty ratio Duty_P of the pump 23 This is because it is difficult to accurately grasp the ratio R1. This step S21 can be determined in the form of whether or not the drive duty ratio Duty_V exceeds a predetermined threshold Duty_V_thre, for example, as shown in FIG. The determination in step S21 is repeated until it is determined that the drive duty ratio Duty_V of the reducing agent injection valve 25 is within the predetermined range (Yes determination).

  If it is determined that the drive duty ratio Duty_V of the reducing agent injection valve 25 is within the predetermined range, the ECU 40 proceeds to step S22 and determines whether or not the supply pressure Pu of the liquid reducing agent is stable at the set pressure Pu_tgt. . Similar to the first abnormality determination, for example, when the supply pressure Pu is close to the set pressure Pu_tgt for a predetermined time, it can be determined that the supply pressure Pu is stable at the set pressure Pu_tgt. If the supply pressure Pu is not stable at the set pressure Pu_tgt (No determination), the routine is temporarily terminated because the second abnormality determination cannot be executed.

  On the other hand, when the supply pressure Pu is stable at the set pressure Pu_tgt (Yes determination), the process proceeds to step S23 and is already stored in the first abnormality determination together with the drive duty ratio Duty_P2 of the pump 23 at that time. The drive duty ratio Duty_P1 of the pump 23 in the non-injection state of the liquid reducing agent is read.

  Next, in step S24, the ECU 40 subtracts the drive duty ratio Duty_P1 of the pump 23 in the non-injection state from the drive duty ratio Duty_P2 of the pump 23 in the injection state of the liquid reducing agent to calculate the change amount ΔDp. In step S25, the ratio R1 of the change amount ΔDp of the drive duty ratio Duty_P of the pump 23 to the change amount ΔDv of the drive duty Duty_V of the reducing agent injection valve 25 is calculated. Since the driving duty ratio Duty_V of the reducing agent injection valve 25 in the non-injecting state of the liquid reducing agent is zero, the change amount ΔDv of the driving duty ratio Duty_V of the reducing agent injection valve 25 at this time is determined as Yes in step S21. The value of the drive duty ratio Duty_V (= Duty_V2) at that time is used.

  When the ratio R1 is obtained, the ECU 40 performs abnormality determination by comparing the ratio R1 with the fourth threshold value Thre4 and the fifth threshold value Thre5 in step S26.

FIG. 9 is a table summarizing how to determine the cause of the abnormality by the second abnormality determination.
When the ratio R1 obtained in step S25 is equal to or greater than the fourth threshold Thre4, the ECU 40 determines that the liquid reducing agent has leaked from a portion other than the reducing agent injection valve 25.
In addition, when the ratio R1 is less than the fourth threshold Thre4 and exceeds the fifth threshold Thre5, the ECU 40 determines that no abnormality has occurred in the reducing agent supply device 20.
Further, when the ratio R1 is equal to or smaller than the fifth threshold value Thre5, the ECU 40 does not move when the reducing agent injection valve 25 is closed or when the reducing agent injection valve 25 is closed or when the reducing agent injection valve 25 is open. It is determined that a sliding failure has occurred.

  Returning to FIG. 7, after executing the first abnormality determination and the second abnormality determination, the ECU 40 proceeds to step S <b> 13 and determines the abnormality based on the determination results of the first abnormality determination and the second abnormality determination. The presence / absence of the occurrence and the cause of the abnormality are determined. As described above, in the present embodiment, the presence / absence of an abnormality and the cause of the abnormality are determined based on the error map shown in FIG.

  Thereafter, the ECU 40 proceeds to step S14 and performs error processing according to the cause of the abnormality. If no abnormality is found, this routine is terminated without doing anything. On the other hand, if the occurrence of an abnormality is found and the cause is determined, a record indicating the occurrence of the abnormality and the cause is left, and the contents of the injection control are changed according to the cause of the abnormality, An informing means for informing the engine driver or the like of the cause of the abnormality is activated.

3. Effects of the abnormality detection device and the reducing agent supply device of the second embodiment After the abnormality detection device 40 and the reducing agent supply device 20 according to the second embodiment described above execute the first abnormality determination, The second abnormality determination is performed based on the change amount ΔDv of the drive duty ratio Duty_V of the reducing agent injection valve 25 and the change amount ΔDp of the drive duty ratio Duty_P of the pump 23 in the liquid reducing agent injection state. Therefore, even in the liquid reducing agent injection state, it is possible to determine the cause of the abnormality of the reducing agent supply device 20 that cannot be determined by the supply pressure Pu of the liquid reducing agent.

  Further, the abnormality detection device 40 and the reducing agent supply device 20 according to the second embodiment are configured to determine whether the reducing agent injection valve 25 is blocked and the liquid reducing agent leaks in the second abnormality determination. . Therefore, it is possible to estimate the cause of an abnormality that cannot be determined only by the first abnormality determination.

  Then, the abnormality detection device 40 and the reducing agent supply device 20 according to the second exemplary embodiment comprehensively evaluate the determination results of the first abnormality determination and the second abnormality determination, and the reducing agent supply device. 20 to determine the cause of the abnormality that occurred. Therefore, the cause of the abnormality that has occurred in the reducing agent supply device 20 can be more specifically identified and determined.

[Other embodiments]

  The abnormality detecting device 40 and the reducing agent supply device 20 of the reducing agent supply device according to the first and second embodiments described so far show one aspect of the present invention and do not limit the present invention. However, it can be arbitrarily changed within the scope of the present invention.

  For example, in the abnormality detection device 40 according to the first and second embodiments, the first threshold value Thre1 and the second threshold value that are set to one value as the threshold values used in the first abnormality determination and the second abnormality determination, respectively. Although the threshold value Thre2, the third threshold value Thre3, the fourth threshold value Thre4, and the fifth threshold value Thre5 are set, a plurality of values can be set step by step. By setting a plurality of values in this way, it is possible to determine not only the cause of abnormality but also the degree of abnormality.

10: exhaust purification device, 11: exhaust passage, 13: reduction catalyst, 20: reducing agent supply device, 21: tank, 23: pump, 23a: inlet side, 23b: outlet side, 25: reducing agent injection valve, 27: First supply passage, 28: second supply passage, 29: return passage, 30: pump unit, 31: pressure sensor, 33: flow path switching valve, 35: check valve, 37: throttle passage, 40: ECU (Reducing agent supply device abnormality detection device), 41: pump drive control unit, 43: reducing agent injection valve drive control unit, 45: abnormality determination unit

Claims (8)

A pump for pumping the liquid reducing agent contained in the tank, a reducing agent injection valve for injecting the liquid reducing agent pumped by the pump into an exhaust pipe of an internal combustion engine, the pump and the reducing agent A supply passage connecting the injection valve, a return passage branched from the supply passage to return the excess liquid reducing agent to the tank, a throttle passage or a check valve provided in the return passage, and the supply passage Pressure detecting means for detecting the internal pressure, and the drive amount of the pump is controlled so that the pressure of the liquid reducing agent supplied to the reducing agent injection valve is maintained at a predetermined set pressure. In the abnormality detecting device of the reducing agent supply device for detecting an abnormality occurring in the reducing agent supply device,
An abnormality determination unit that determines a cause of an abnormality of the reducing agent supply device based on a driving amount of the pump in a non-injecting state of the liquid reducing agent ;
The abnormality determination unit, after making a determination based on the driving amount of the pump in the non-injection state, further changes the driving amount of the reducing agent injection valve in the injection state of the liquid reducing agent and the driving of the pump. abnormality detection device of the reducing agent supply apparatus characterized that you determine an abnormality occurring in the reducing agent supply device based on the amount of variation.   While the abnormality determination unit determines that the liquid reducing agent has leaked when the drive amount of the pump in the non-injection state is equal to or greater than a first threshold value greater than a predetermined reference value, It is determined that the throttle passage or the check valve is blocked when the drive amount of the pump in the non-injection state is equal to or smaller than a second threshold value that is smaller than the reference value. The abnormality detection apparatus of the reducing agent supply apparatus according to claim 1.   The abnormality determination unit further includes a driving amount of the pump in the non-injection state that is equal to or greater than a third threshold value that is larger than the reference value and smaller than the first threshold value, and the first The abnormality detection device for a reducing agent supply device according to claim 2, wherein it is determined that deterioration with time of the pump has occurred when smaller than a threshold value.   The abnormality determination unit reads the driving amount of the pump stored in the non-injection state, and compares the determination with the first threshold value, the second threshold value, and the third threshold value, respectively. The abnormality detection device for a reducing agent supply device according to claim 3, wherein the abnormality detection device is performed. The abnormality determination unit is configured to reduce the reducing agent injection valve when a ratio between a change amount of the driving amount of the reducing agent injection valve and a change amount of the driving amount of the pump in the injection state is equal to or less than a predetermined fifth threshold value. When the ratio between the change amount of the driving amount of the reducing agent injection valve and the change amount of the drive amount of the pump in the injection state is equal to or greater than a predetermined fourth threshold value It determines with the leakage of the said liquid reducing agent having arisen, The abnormality detection apparatus of the reducing agent supply apparatus as described in any one of Claims 1-4 characterized by the above-mentioned. The abnormality determination unit reads the drive amount of the pump stored in the non-injection state, the drive amount of the reducing agent injection valve and the drive amount of the pump stored in the injection state,
A ratio between the difference between the drive amount of the pump stored in the injection state and the drive amount of the pump stored in the non-injection state and the drive amount of the reducing agent injection valve stored in the injection state The abnormality detection device for a reducing agent supply device according to any one of claims 1 to 5, wherein the determination is performed based on the determination. The abnormality determination unit comprehensively evaluates a determination result in the non-injection state and a determination result in the injection state to determine the cause of the abnormality of the reducing agent supply device. The abnormality detection device for a reducing agent supply device according to any one of claims 1 to 6 . A pump for pumping the liquid reducing agent contained in the tank, a reducing agent injection valve for injecting the liquid reducing agent pumped by the pump into an exhaust pipe of an internal combustion engine, the pump and the reducing agent A supply passage connecting the injection valve, a return passage branched from the supply passage to return the excess liquid reducing agent to the tank, a throttle passage or a check valve provided in the return passage, and the supply passage Pressure detecting means for detecting the pressure in the inside, and an electronic control unit for controlling the driving of the pump and the reducing agent injection valve, and the liquid reducing agent supplied to the reducing agent injection valve In the reducing agent supply device in which the drive amount of the pump is controlled so that the pressure is maintained at a predetermined set pressure ,
The electronic control unit includes an abnormality determination unit that determines a cause of abnormality of the reducing agent supply device based on a driving amount of the pump in a non-injecting state of the liquid reducing agent .
The abnormality determination unit, after making a determination based on the driving amount of the pump in the non-injection state, further changes the driving amount of the reducing agent injection valve in the injection state of the liquid reducing agent and the driving of the pump. the amount of variation and the reducing agent supply apparatus characterized that you determine an abnormality occurring in the reducing agent supply device based on.

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