JP6508475B2 - Diagnostic device - Google Patents

Description

  The present invention relates to a diagnostic device that is applied to a urea water supply system that supplies urea water to an injector and that diagnoses the quality of urea water and an abnormality in the urea water supply system.

  Conventionally, a urea SCR (Selective Catalytic Reduction) system is known as one of the systems for purifying exhaust gas emitted from an internal combustion engine. In the urea SCR system, the exhaust pipe of the internal combustion engine is provided with a NOx catalyst that selectively reduces and purifies NOx in the exhaust gas with urea water, and an injector that adds urea water to the exhaust upstream side of the NOx catalyst. Further, the urea SCR system is provided with a urea water supply system for supplying urea water to the injector. The urea water supply system includes a tank for storing urea water, a pump for sucking in and discharging the urea water in the tank, and a pipe for leading the urea water discharged from the pump to an injector.

  The concentration of urea water used in the urea SCR system is set to a desired value (for example, 32.5%). However, with respect to the standard concentration corresponding to the desired value, urea water of an unexpected concentration may be used, or what was initially the standard concentration may change with time. In addition, when used in a cold area where the temperature drops to below freezing, the urea water in the tank may be cooled and frozen while the vehicle is stopped. During the freezing or thawing process, the distribution of urea in the aqueous urea solution is biased, and as a result, the concentration of aqueous urea solution supplied to the injector may become an unexpected concentration.

  If the concentration of urea aqueous solution supplied to the injector is higher than expected, urea may be excessively supplied to the NOx catalyst, which may generate a slip in which ammonia is released from the NOx catalyst. On the other hand, when the concentration of urea water is lower than expected, the NOx purification rate at the NOx catalyst may be reduced.

  On the other hand, although it is a technology different from urea solution concentration diagnosis, there has conventionally been proposed a technology for calculating the viscosity of fuel based on the operating state of an electric pump that sucks and discharges fuel (see Patent Document 1). In Patent Document 1, the fuel viscosity is calculated based on the time until the operating state of the electric pump reaches a first steady state to a second steady state.

Patent No. 4840531

  By the way, in order to diagnose the concentration or viscosity of urea water, it is conceivable to provide a sensor for detecting the quality (concentration or viscosity) of urea water in the tank. However, as described above, bias may occur in the urea distribution in urea water, in which case the concentration or viscosity of urea water detected by the sensor and the concentration or viscosity of urea water actually supplied from the pump to the injector are It may be different. That is, for example, when the quality sensor is provided in a region where the concentration of urea water is low, and the pump is provided in a region where the concentration of urea water is high, the concentration of urea water discharged by the pump is Despite the high concentration, the quality sensor detects low concentration. In addition, the provision of the quality sensor leads to an increase in cost.

  In addition, abnormalities in the urea water supply system such as freezing of the urea water, motor abnormality of the pump, leak of the urea water from the piping, etc. may occur.

  The present invention has been made in view of the above circumstances, and can diagnose the concentration or viscosity of urea water supplied to the injector and abnormality of the urea water supply system without using a quality sensor for detecting the quality of urea water It is an object to provide a diagnostic device.

In order to solve the above-mentioned subject, a diagnostic device of the present invention is the tank (6) which stores urea water, and
A pump (8) for sucking in and discharging urea water stored in the tank;
The invention is applied to a urea water supply system including a pipe (9) for leading urea water discharged from the pump to the injector,
A motor control unit (S4, S6) for performing control to change a rotational state of a motor (10) of the pump;
A rotational behavior acquisition unit (S11, S31) for acquiring a rotational behavior of the motor at the time of performing the control;
A pressure behavior acquisition unit (S11, S31) for acquiring pressure behavior in the pipe at the time of execution of the control;
A diagnosis unit (S12 to S20, S32 to S40, S8) that diagnoses the concentration or viscosity of urea water based on the rotational behavior and the pressure behavior and an abnormality of the urea water supply system;
Equipped with

  The present inventors have found that the viscosity of urea water changes according to the concentration of urea water. The present invention has been made based on this finding, and the viscosity changes according to the concentration of urea water, and the motor rotation behavior when control is performed to change the rotation state of the pump motor according to the viscosity is Change. Furthermore, not only the concentration or viscosity of the aqueous urea solution but also the abnormality of the aqueous urea solution supply system can be diagnosed by looking at the pressure behavior in the pipe in addition to the rotational behavior. That is, the rotational behavior and the pressure behavior reflect the concentration or viscosity of urea water, and when a system abnormality occurs, the behavior differs from the behavior reflecting the concentration or viscosity of urea water. In the present invention, the diagnosis unit diagnoses the concentration or viscosity of urea water and the system abnormality based on the rotational behavior and the pressure behavior, so that the diagnosis can be performed without using the quality sensor.

It is a whole block diagram of a urea SCR system. While extracting the structure relevant to supply of the urea water to an injector out of a urea SCR system, it is the figure which showed the internal structure of the pump unit. It is the figure which showed the correlation characteristic of the density of urea water, and viscosity. It is the figure which illustrated the behavior of the motor rotation speed in the time of electricity supply start and stop to a pump motor, and the pressure behavior in piping. It is a flowchart of the process which diagnoses the density | concentration of urea water and system abnormality which ECU performs. FIG. 6 is a specific process of S5 of FIG. 5, which is a flowchart of a process of temporarily diagnosing the concentration of urea water at the start of motor energization and a system abnormality. FIG. 6 is a specific process of S7 of FIG. 5, which is a flowchart of a process of temporarily diagnosing the concentration of urea water and motor system abnormality at the time of motor power supply stoppage. FIG. 6 is a specific process of S8 of FIG. 5, which is a flowchart of a process of performing a comprehensive diagnosis based on a temporary diagnosis result at the start of motor energization and a temporary diagnosis result at the time of motor energization stop.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the overall configuration of a urea SCR system to which the present invention is applied. The urea SCR system 1 is a system which is mounted on a vehicle and purifies NOx in the exhaust gas emitted from an engine 2 as an internal combustion engine. The engine 2 is, for example, a diesel engine that includes a cylinder and an injector that injects fuel into the cylinder, and self-ignites the fuel injected from the injector in the cylinder.

The urea SCR system 1 includes an SCR catalyst (NOx catalyst) 4 for selectively reducing and purifying NOx in the exhaust gas to the exhaust pipe 3 of the engine 2 and urea directly to the exhaust upstream side of the SCR catalyst 4 or the SCR catalyst 4 And an injector 5 for adding water. The SCR catalyst 4 stores ammonia (NH 3) generated by hydrolysis of urea water added from the injector 5 due to exhaust heat, and, as a reduction reaction of the ammonia (NH 3) and NOx, for example, the following formula A catalyst component that promotes the reduction reaction of 1, 2, and 3 is supported. The catalyst component is, for example, a base metal oxide such as vanadium, molybdenum or tungsten. Thus, while the exhaust gas passes through the SCR catalyst 4, NOx is decomposed (purified) into water or nitrogen according to, for example, the following formulas 1, 2, and 3.
4NO + 4NH3 + O2 → 4N2 + 6H2O (Equation 1)
6 NO 2 + 8 NH 3 → 7 N 2 + 3 H 2 O (Equation 2)
NO + NO 2 + 2 NH 3 → 2 N 2 + 3 H 2 O (Equation 3)

  The SCR catalyst 4 can not store ammonia in an exhaustive manner, and the maximum storage amount of ammonia that can be stored in the SCR catalyst 4 changes depending on the temperature of the SCR catalyst 4 (catalyst temperature). When the catalyst temperature falls sharply or when ammonia (urea) is excessively supplied to the SCR catalyst 4, a phenomenon called ammonia slip occurs in which ammonia is released from the SCR catalyst 4. Therefore, an oxidation catalyst for purifying the ammonia released from the SCR catalyst 4 may be provided downstream of the SCR catalyst 4.

  The injector 5 has the same structure as a fuel injection valve that injects fuel into a cylinder of a gasoline engine or into an intake port. That is, the injector 5 is configured as an electromagnetic on-off valve including a nozzle in which an injection hole is formed, a drive unit such as an electromagnetic solenoid, and a urea water passage for circulating urea water and a needle for opening and closing the nozzle. It is done. Then, when the electromagnetic solenoid is energized, the needle moves in the valve opening direction with the energization, and urea water is injected from the injection hole formed at the tip of the nozzle with the movement of the needle.

  In addition, the urea SCR system 1 includes a urea water supply system for supplying urea water to the injector 5. The urea aqueous solution supply system leads the tank 6 for storing urea aqueous solution, the pump unit 8 for sucking in and discharging the urea aqueous solution stored in the tank 6, and guides the urea aqueous solution discharged from the pump unit 8 to the injector 5. It is constituted including piping 9.

  The tank 6 is fixed to, for example, a chassis frame of a vehicle and is exposed to the outside air. The tank 6 is constituted by a closed container having a supply port 7. When the amount of urea water is reduced, the tank 6 can be replenished with urea water from the supply port 7.

  The pump unit 8 is an in-tank pump disposed so as to be immersed in urea water at the bottom of the tank 6. In place of the in-tank pump, a pump of a type in which the pump body is disposed outside the tank may be employed. The pump unit 8 is an electric pump that is rotationally driven by a drive signal from the ECU 19. Specifically, as shown in FIG. 2, the pump unit 8 includes a pump motor 10 that is driven to rotate by a drive signal from the ECU 19, and a pump impeller (impeller) 11 attached to the rotation shaft of the pump motor 10. A urea water filter 12 for removing foreign substances in urea water, and a pump heater 13 provided so as to surround the periphery of the pump motor 10 to warm the inside of the pump unit 8 including the pump motor 10 are provided.

  The pump motor 10 is, for example, a three-phase induction motor, and is configured to be able to change the number of rotations of the rotor by changing the frequency of the drive signal applied to the stator side (primary side). In addition, the pump motor 10 can switch the rotation direction of the rotor between the normal direction in which urea water is discharged (pumped) to the side of the injector 5 and the reverse direction in which the urea water is sucked back into the tank 6 It is configured.

  In the pump unit 8 configured in this way, the pump impeller 11 rotates with the rotation of the pump motor 10, and the rotation attracts and discharges the urea water in the tank 6, or the residual urea water in the pipe 9 is discharged. Suck back into the tank 6 Further, the pump unit 8 is configured to be able to variably adjust the pumping amount of the urea water (pump discharge amount) by changing the rotational speed of the pump motor 10. At this time, as the rotational speed of the pump motor 10 increases, the pressure feed amount of the urea water increases, and the pressure in the pipe 9 increases due to the increase.

  In the tank 6, a tank heater 14 for heating the urea water in the tank 6 is provided so as to be immersed in the urea water. The tank heater 14 is connected to the pump heater 13, and the pump heater 13 is also energized when the tank heater 14 is energized by the ECU 19.

  One end of the pipe 9 is connected to the discharge port of the pump unit 8, and the other end is connected to the urea water inlet of the injector 5. The urea water discharged from the pump unit 8 flows in the pipe 9 and is supplied into the injector 5 from the urea water inlet of the injector 5.

  The urea SCR system 1 is provided with various sensors necessary for control of the urea SCR system 1. Specifically, the tank 6 is provided with a urea water temperature sensor 15 that detects the temperature of urea water in the tank 6. The pipe 9 is provided with a pressure sensor 16 for detecting the pressure in the pipe 9. The pressure sensor 16 is provided closer to the injector 5 than the pump unit 8. Further, an outside air temperature sensor 17 for detecting the outside air temperature and an engine water temperature sensor 18 for detecting the cooling water temperature of the engine 2 are provided. The detected values of these sensors are input to the ECU 19. In addition, an RPM sensor for detecting the engine RPM, an accelerator sensor for detecting the accelerator operation amount (accelerator opening degree) by the driver, an NOx sensor provided downstream of the SCR catalyst 4 for detecting NOx concentration in exhaust gas, etc. It is provided.

  Further, the urea SCR system 1 includes an ECU 19. The ECU 19 includes a well-known microcomputer including a CPU, a ROM, a RAM, and the like. The ECU 19 controls the amount of urea water added by the injector 5 based on, for example, the operating state of the engine 2 or the detected value of the NOx sensor. Further, the ECU 19 has a motor drive circuit 20 that generates a drive signal to be output to the pump motor 10, and controls the rotation of the pump motor 10. Further, the ECU 19 has a drive state detection circuit 21 that detects a signal (for example, drive current or drive voltage) actually generated in the pump motor 10 in response to a drive signal (for example, drive voltage) supplied from the motor drive circuit 20. Further, the ECU 19 controls energization of the heaters 13 and 14.

  Further, the ECU 19 executes processing for determining the concentration of urea water stored in the tank 6 and determining abnormality of the urea water supply system such as freezing of the urea water. Here, before describing the details of this process, the concentration and freezing of urea aqueous solution will be described. In the urea SCR system 1, a desired value (for example, 32.5%) of the concentration of urea water used (the concentration of urea contained in the urea water) is determined. However, an unexpected concentration of urea water may be used for a standard concentration corresponding to the desired value. In addition, when used in a cold area where the temperature drops to below freezing, the urea water in the tank 6 may be cooled and frozen while the vehicle is stopped. The urea water freezes at -11 ° C, but the freezing does not start uniformly in each region in the tank 6, but freezes from the surface side of the urea water near the outside air. Moreover, in the process of freezing, it will freeze from the water | moisture content contained in urea water, As a result, urea will gather at the liquid side which freezing has not progressed. As a result, when the urea aqueous solution is partially frozen, the concentration of urea in the non-frozen portion may be higher than the standard concentration. As described above, the distribution of urea in the aqueous urea solution is biased in the process of freezing, which also applies to the process of thawing.

  When urea water of an unexpected concentration is supplied to the injector 5, an ammonia slip may be generated to release excess ammonia from the SCR catalyst 4, or the NOx purification rate at the SCR catalyst 4 may be reduced. . In order to suppress this, it is useful to determine the concentration of urea water actually supplied to the injector 5.

  Further, when the urea water is completely frozen, the supply of the urea water to the injector 5 becomes impossible, and it is necessary to wait for the thawing of the urea water. On the other hand, when part of the urea aqueous solution is frozen and part is not frozen, the urea aqueous solution can be supplied to the injector 5 when the pump unit 8 is disposed in the non-frozen region. is there. In this case, if it is waiting for all of the urea water to completely freeze, the implementation of the NOx purification by the SCR catalyst 4 is delayed. Therefore, it is necessary to determine the frozen state of the urea water in as short time as possible.

  In the present embodiment, the concentration determination is performed using the correlation of the concentration of urea water with the viscosity. Here, referring to FIG. 3, the correlation characteristic between the concentration of urea water and the viscosity will be described. As shown in FIG. 3, the correlation characteristic between the concentration of urea aqueous solution and the viscosity has an inflection point at a certain concentration, and the tendency of the viscosity change with respect to the concentration change changes at the inflection point. Specifically, in the range of concentration lower than the specified concentration indicating the inflection point, the change in viscosity relative to the concentration change is small. That is, even if the concentration changes, the viscosity has a substantially constant value. On the other hand, when the concentration is higher than the specified concentration, the viscosity change to the concentration change is large. Specifically, the higher the concentration, the higher the viscosity.

  Further, in FIG. 3, the specified concentration which is the inflection point is set around the standard concentration (32.5%) of urea water. In the normal temperature line (solid line) of FIG. 3, the ratio of the viscosity at 34.2% and 40% concentration to the viscosity at 32.5% concentration is about 1.05 times and 1 respectively. It is tripled.

  In addition, the viscosity of urea water also changes depending on the temperature, and specifically, the lower the temperature, the higher the viscosity. In FIG. 3, the viscosity (dotted line) at low temperature (0 ° C.) is about 1.8 times higher than the viscosity (solid line) at normal temperature (20 ° C.). Further, the rate of change in viscosity with respect to the change in concentration is equal between the correlation characteristic of the concentration and viscosity at normal temperature (solid line) and the correlation characteristic at low temperature (dotted line).

  Thus, the viscosity changes according to the concentration or temperature, and the rotation behavior of the pump motor 10 changes when the control for changing the rotational state of the pump motor 10 is performed according to the viscosity. Further, since the pressure in the pipe 9 changes accompanying the rotation of the pump motor 10, the pressure behavior when the control for changing the rotational state of the pump motor 10 is performed changes according to the viscosity. This will be described in more detail with reference to FIG.

  4 shows, from the top, the state of energization of the pump motor with respect to time (FIG. 4 (a)), the change in the rotational speed of the pump motor (FIG. 4 (b)), and the change in pipe pressure (FIG. 4 (c)) ) Is shown. Further, in (b) and (c), the line (dotted line) of (1) shows the behavior when using urea water at normal temperature and standard concentration. The line (2) (dotted-dotted line) shows the behavior when low temperature and standard concentration of urea water are used. The line (solid line) of (3) shows the behavior when urea water at normal temperature and higher than the standard concentration is used. As described in FIG. 3, the higher the concentration, the higher the viscosity, and the lower the temperature, the higher the viscosity. Therefore, the viscosity increases in the order of (1), (2), and (3).

  The rotational behavior at the start of motor energization will be described. The time from when the motor energization is turned on to when the motor actually starts to rotate (rotation start delay time) becomes longer as the viscosity, that is, the concentration increases. That is, the rotation start delay time has a relationship of (1) <(2) <(3). Also, when the concentration is high, the rate of increase of the rotational speed (the rate of increase of the portion 100 in FIG. 4B) with respect to time in the change process from the start of rotation to the steady state It is lower than 1) and 2). This is because when the concentration is high, the viscosity is high and the resistance is high, making it difficult for the motor to rotate.

  To explain the pressure behavior at the start of motor energization, the delay time from the ON of motor energization to the actual start of increase in pipe pressure is longer as the viscosity, ie, the concentration is higher. Similarly to (1) <(2) <(3).

  The rotational behavior at the end of the motor energization will be described. The time from the motor energization OFF to the actual start of the motor rotational speed drop (descent start delay time) becomes longer as the viscosity, that is, the concentration increases. In addition, when the concentration is high, the rate of decrease of the number of revolutions (rate of decrease of the part denoted by 101 in FIG. 4B) with respect to the time in the change process from the start of the descent to the steady state (rotation stop) It will be lower than when the concentration is low (cases (1) and (2)). This is because when the concentration is high, the viscosity is high, and therefore it is difficult for the urea water acting on the pump impeller to be separated from the pump impeller. Then, the flow of the urea water acting on the pump impeller causes the time after which the motor after the motor is turned off becomes longer with the inertia (inertia).

  The pressure behavior at the end of motor energization will be described. The time from when the motor energization is turned off to when the piping pressure actually starts to drop is longer as the viscosity, that is, the concentration is higher. Specifically, (1) <( 2) <(3) In addition, when the concentration is high (in the case of (3)), the pressure decrease rate with respect to time in the change process from the start of pressure drop to the steady state (pressure zero) is in the cases of (1) and (2) It is lower than it. This is because, as described above, when the concentration is high, the time for the motor to coast and take turns becomes long.

  When the concentration is high, the viscosity is high, the resistance to the motor rotation is high, and it can be considered that the number of rotations drops rapidly when the motor is turned off. That is, when the concentration (viscosity) is high, it can be considered that the delaying start delay time at the time of the power-off is short as compared with the case where the concentration (viscosity) is low. However, in the present embodiment, as described above, when the concentration is high, the fall start delay time when the motor is turned off is longer than when the concentration is low, and the rotation drop rate and the pressure drop rate are lowered. It uses the knowledge.

  Fig. 4 shows the rotational behavior and pressure behavior due to the difference in the concentration (viscosity) of the aqueous urea solution, but if an abnormality occurs such as when the aqueous urea solution is frozen, the rotational behavior and the pressure behavior are the types of the generated anomalies ( The behavior reflects the freezing of urea water, motor abnormality, and piping leaks.

  The ECU 19 uses the knowledge shown in FIGS. 3 and 4 to perform abnormality determination such as the concentration of urea water or freezing. The details of the process executed by the ECU 19 will be described below. FIG. 5 shows a flowchart of processing executed by the ECU 19. The process of FIG. 5 starts when a predetermined condition is satisfied, such as when the engine 2 is started.

  When the process of FIG. 5 is started, the complete freezing determination of the urea water in the tank 6 is first performed (S1). Here, complete freezing refers to a state in which the aqueous urea solution supply to the injector 5 is apparently impossible, or in other words, a state in which all the aqueous urea solution is frozen. Specifically, for example, the urea water temperature detected by the urea water temperature sensor 15 is the predetermined threshold A or less, and the outside temperature detected by the outside air temperature sensor 17 is the predetermined threshold B or less. If the cooling water temperature detected by the engine water temperature sensor 18 is less than or equal to a predetermined threshold C, it is determined that complete freezing has occurred, and even one of the urea water temperature, the outside air temperature, and the cooling water temperature is higher than the threshold, complete freezing It determines that it does not do. The threshold is set, for example, to a temperature (for example, -20.degree. C.) lower than -11.degree. C. at which urea aqueous solution freezes. Note that the threshold values A, B, and C may be set to the same temperature as each other, or may be set to different temperatures. Thus, by determining complete freezing based on the urea water temperature, the outside air temperature, and the cooling water temperature, complete freezing can be determined more accurately than when determination is made using only the urea water temperature.

  If it is determined that the pump motor 10 is completely frozen (S2: Yes), energization of the pump motor 10 by the motor drive circuit 20 is stopped to protect the pump motor 10 (S3). In addition, the heaters 13 and 14 are energized to thaw the urea aqueous solution to heat the urea aqueous solution in the pump unit 8 and the urea aqueous solution in the tank 6 (S3). Thereafter, the process of FIG. 5 is ended.

  On the other hand, when it is determined that the pump motor 10 is not completely frozen (S2: No), energization of the pump motor 10 is started by the motor drive circuit 20 (S4). That is, the pump motor 10 is rotated in the normal direction to start the urea water supply to the injector 5. At this time, the target value of the piping pressure is set, and the frequency of the drive signal to be output from the motor drive circuit 20 to the pump motor 10 is set so that the piping pressure becomes this target value. In addition, the process of S4 is an example of raising control which is changed in the direction which raises the rotation speed of the pump motor 10.

  Next, the concentration of urea water, freezing and the like are determined based on the rotational behavior of the pump motor 10 and the pressure behavior of the pipe 9 at the start of motor energization (S5). Specifically, the process of FIG. 6 is performed.

  In the process of FIG. 6, first, the rotational behavior of the pump motor 10 and the pressure behavior of the pipe 9 at the start of motor energization are acquired (S11). Specifically, for the rotational behavior, the drive state detection circuit 21 detects a signal (for example, a drive current) actually generated in the pump motor 10 after the start of motor energization. The generated signal fluctuates with a cycle corresponding to the number of rotations of the pump motor 10. Therefore, the motor rotational speed is determined based on the cycle of the generated signal. The motor rotation number is sequentially acquired over a period from the start of motor energization to the start of rotation of the motor to the steady state of motor rotation. Here, the steady state of motor rotation refers to a state in which the number of revolutions is constant with time, and in other words, a state in which the rate of change in the number of revolutions with respect to time is substantially zero. A sensor for detecting the rotational speed of the pump motor 10 may be provided in the pump unit 8, and the motor rotational speed may be acquired by the sensor.

  In S11, based on the acquired behavior of the motor rotational speed, the rotation start delay time (corresponding to the rise delay time of the present invention) from when the motor energization is started to when the rotation of the pump motor 10 actually starts is calculated. . Furthermore, based on the rotational speed behavior, the rate of increase (the rate of increase in rotational speed) of the rotational speed with respect to the time in the changing process from when the motor actually starts rotating until it reaches a steady state is calculated. Specifically, for example, the instantaneous rotation increase rate at each point in the rotation increase period from the start of rotation to the steady state is determined for each point, and the average value of the instantaneous rotation increase rates for each point obtained is finally determined. Adopted as a rate of increase in Further, the rotation increase period is divided into a plurality of sections with a predetermined time width, and the rotation increase rate is calculated for each section. Then, the maximum value of the rate of increase in rotation for each section may be adopted as the final rate of increase in rotation.

  As the pressure behavior of the pipe 9, the detection value of the pressure sensor 16 is sequentially acquired over the period from the start of motor energization to the start of the pipe pressure rise to the steady state of the pipe pressure. Here, the steady state of the piping pressure refers to a state in which the piping pressure becomes constant at a target value with respect to the passage of time, in other words, a state in which the rate of change of the piping pressure with respect to time is substantially zero.

  In S11, based on the acquired pressure behavior, the rate of increase (pressure increase rate) of the piping pressure with respect to the time in the change process from the start of pressure rise to the steady state is calculated. The calculation method of the pressure increase rate is the same as the calculation method of the rotation increase rate. The rotational behavior (rotation start delay time, rotational increase rate) and pressure behavior (pressure increase rate) acquired in S11 are stored in a memory in the ECU 19. The rotation start delay time and the rotation increase rate may be calculated at the determination timings of S12 and S14 described later, and the pressure increase rate may be calculated at the determination timings of S15 and S18 described later.

  Next, it is determined whether the rotation start delay time obtained in S11 is smaller or larger than a predetermined threshold T1 (S12). The threshold T1 is set to a value larger than the rotation start delay time of the lines (1) and (2) in FIG. 4B and smaller than the rotation start delay time of the line (3). If the rotation start delay time is smaller than the threshold T1, the concentration of urea water is a standard concentration (for example, 32.5%), and the pump motor 10 is tentatively diagnosed as operating normally (S13). The reason for temporary diagnosis in this way is that the viscosity of urea water is lower in the case of standard concentration than in the case of high concentration (see FIG. 3), and the rotation start delay time is shorter as the viscosity is lower. (Refer FIG.4 (b)). Further, even if the concentration is the standard concentration, the rotation start delay time becomes long when the pump motor 10 is not operating normally. That is, that the rotation start delay time is short means that the pump motor 10 is normal.

  On the other hand, when the rotation start delay time is larger than the threshold T1, it is determined whether the rotation increase rate obtained in S11 is larger or smaller than a predetermined threshold R1 (S14). The threshold R1 is set to a value smaller than the rate of increase in rotation of the lines (1) and (2) in FIG. 4B and larger than the rate of increase in rotation of the line of (3). If the rotation increase rate is larger than the threshold value R1, the pump motor 10 is considered to be normal, and then it is determined whether the pressure increase rate obtained in S11 is larger or smaller than a predetermined threshold value P1. (S15). Also, when it is determined in S13 that the standard concentration and the motor are normal, it is next determined whether the pressure increase rate is larger or smaller than the threshold P1 (S15). This S15 is a process for determining whether a standard concentration or a pipe leak is present rather than determining whether the concentration is a standard concentration or a high concentration. The threshold value P1 is set to a value smaller than the pressure increase rate of the lines (1) and (2) in FIG. 4 (c).

  If the pressure increase rate is larger than the threshold value P1, the concentration of urea water is finally determined as the standard concentration and the motor is normal as the determination at the start of motor energization (S16). As described above, in the process of FIG. 6, either the rotation start delay time is smaller than the threshold T1 or the rotational increase rate is larger than the threshold R1, and the pressure increase rate is larger than the threshold P1. It is determined that the standard concentration and the motor are normal. This is because, as shown in FIGS. 4 (b) and 4 (c), in the behavior of (1) and (2) showing the standard concentration, the rotation start delay time is longer than the behavior of the high concentration of (3). It is because it is short and the rate of increase in rotation is high. Moreover, when the behaviors of (1) and (2) are compared in FIG. 4 (b), even if the standard concentration is the same, the rotation start delay time changes due to the difference in temperature. The start delay time becomes long. Therefore, in the process of FIG. 6, even if it is determined that the rotation start delay time is larger than the threshold T1 due to the temperature decrease, the standard concentration can be assured by confirming the rotation increase rate and the pressure increase rate as well. Can be detected. Further, assuming that the pump motor 10 is operating normally, the rate of increase in rotation and the rate of pressure increase are high, so in S16, in addition to the standard concentration, it is also determined that the motor is normal. After S16, the process of FIG. 6 is ended, and the process returns to the process of FIG.

  On the other hand, when the pressure increase rate is smaller than the threshold value P1, it is determined that the urea water is leaking from the pipe 9 because the pipe pressure does not rise although the pump motor 10 is normal (S17). This piping leak is one of the abnormalities of the urea water supply system. In addition, when it progresses to S17 through S13, while it is a piping leak, it is also a standard density | concentration and a motor normality. After S17, the process of FIG. 6 is ended, and the process returns to the process of FIG.

  If the rotation increase rate is smaller than the threshold value R1 in S14, then it is determined whether the pressure increase rate obtained in S11 is larger or smaller than a predetermined threshold value P2 (S18). This S18 is a process for determining whether the concentration is high or the system is abnormal rather than determining whether the concentration is the standard concentration or the high concentration. The threshold value P2 is set to a value smaller than the pressure increase rate of the line (3) in FIG. 4 (c). Note that the threshold value P2 may be set to a value different from the threshold value P1 of S15, or may be set to the same value.

  When the pressure increase rate is larger than the threshold value P2, it is determined that the concentration of urea water is higher than the standard concentration (S19). Thus, in the process of FIG. 6, the high concentration is determined when the rotation start delay time is larger than the threshold T1, the rotation increase rate is smaller than the threshold R1, and the pressure increase rate is larger than the threshold P2. . This is because, as shown in FIGS. 4B and 4C, in the behavior of (3) showing a high concentration, the rotation start delay time is longer than the behavior of the standard concentration of (1) and (2) This is because the rotation increase rate is long and low. After S19, the process of FIG. 6 is ended, and the process returns to the process of FIG.

  If the pressure increase rate is smaller than the threshold value P2 in S18, the motor rotation does not increase either and the increase in the piping pressure is slow, so that the pump motor 10 or the circuit that drives the pump motor 10 has abnormality (hereinafter simply referred to as motor abnormality), Alternatively, it is determined that the urea aqueous solution is frozen (S20). The motor abnormality and the freezing of the urea water are respectively one of the abnormalities of the urea water supply system. After S20, the process of FIG. 6 is ended, and the process returns to the process of FIG. The determination result of the concentration of urea water or the like by the processing of FIG. 6, that is, the determination result of S16, S17, S19 or S20 is stored in the memory in the ECU 19. The process of FIG. 6 is a process of temporarily diagnosing the concentration or the like of urea water, and the diagnosis result is determined by the process of S8 of FIG. 5 described later.

  Referring back to FIG. 5, after S5, next, the energization of the pump motor 10 is stopped (S6). The process of S6 is an example of lowering control for changing the rotational speed of the pump motor 10 in the direction of decreasing it.

  Next, the concentration of urea water, freezing and the like are determined based on the rotational behavior of the pump motor 10 and the pressure behavior of the pipe 9 at the time when the motor energization is stopped (S7). Specifically, the process of FIG. 7 is performed.

  If it transfers to the process of FIG. 7, the pressure behavior of the rotation speed of the pump motor 10 and the pressure behavior of the piping 9 at the time of motor power supply stop are acquired similarly to S11 of FIG. 6 (S31). In S31, based on the behavior of the acquired rotational speed, a descent start delay time from when the motor energization is stopped to when deceleration of the pump motor 10 (reduction of the rotational speed) actually starts is calculated. Further, based on the rotational speed behavior, the rate of decrease of the rotational speed (the rate of decrease in rotational speed) with respect to the time in the change process from the start of deceleration of the motor to the steady state (rotation stop) is calculated. The method of calculating the rate of decrease in rotation is the same as the method of calculating the rate of increase in rotation in S11 of FIG.

  Further, at S31, based on the acquired pressure behavior, the rate of decrease (pressure drop rate) of the piping pressure with respect to the time in the change process from the start of motor deceleration to the time of rotation stop is calculated. The rotational behavior (falling start delay time, rotational decline rate) and pressure behavior (pressure rise rate) acquired in S31 are stored in a memory in the ECU 19. Note that the descent start delay time and the rotation descent rate may be calculated at the determination timings of S32 and S34 described later, and the pressure descent rate may be calculated at the determination timings of S35 and S38 described later.

  Next, it is determined whether the falling start delay time obtained in S31 is smaller or larger than a predetermined threshold T2 (S32). The threshold T2 is set to a value larger than the falling start delay time of the lines (1) and (2) in FIG. 4B and smaller than the falling start delay time of the line (3). If the fall start delay time is smaller than the threshold T2, the concentration of urea water is temporarily diagnosed as the standard concentration (S33). This is because, as described in FIG. 4, in the case of the standard concentration, the viscosity is lower than that in the high concentration, and when the viscosity is low, the time for the motor to rotate along with the motor after turning off the motor becomes short. It is for.

  On the other hand, if the descent start delay time is larger than the threshold T2, then it is determined whether the rotation descent rate obtained in S31 is larger or smaller than a predetermined threshold R2 (S34). The threshold R2 is set to a value smaller than the rotation drop rate of the lines (1) and (2) in FIG. 4B and larger than the rotation drop rate of the line (3). If the rotation decrease rate is larger than the threshold value R2, the pump motor 10 is regarded as normal, and then it is determined whether the pressure decrease rate obtained in S31 is larger or smaller than a predetermined threshold value P3. (S35). Further, also when it is determined in S33 that the standard concentration is set, it is next determined whether the pressure decrease rate is larger or smaller than the threshold P3 (S35). This S35 is a process for determining whether a standard concentration or a pipe leak is present rather than determining whether the concentration is a standard concentration or a high concentration. The threshold value P3 is set to a value larger than the pressure drop rate of the lines (1) and (2) in FIG. 4 (c).

  If the pressure decrease rate is smaller than the threshold value P3, it is determined that the concentration of urea water is the standard concentration (S36). Thus, in the process of FIG. 7, one of the fact that the falling start delay time is smaller than the threshold T2 and the fact that the rotational falling rate is larger than the threshold R2 is satisfied and the pressure falling rate is smaller than the threshold P3. Determined as standard concentration. After S36, the process of FIG. 7 is ended, and the process returns to the process of FIG.

  On the other hand, when the pressure decrease rate is larger than the threshold value P3, it is determined that the urea water is leaking from the pipe 9 because the pressure decrease is abnormally fast (S37). In addition, when it progresses to S37 through S33, while it is piping leak, it is also a standard density | concentration. After S37, the process of FIG. 7 is ended, and the process returns to the process of FIG.

  If the rotation decrease rate is smaller than the threshold R2 in S34, it is next determined whether the pressure decrease rate obtained in S31 is larger or smaller than a predetermined threshold P4 (S38). This S38 is a process for determining whether the concentration is high or system abnormality rather than determining whether the concentration is the standard concentration or the high concentration. The threshold value P4 is set to a value larger than the pressure drop rate of the line (3) in FIG. 4 (c). Note that the threshold value P4 may be set to a value different from the threshold value P3 of S35, or may be set to the same value.

  If the pressure decrease rate is smaller than the threshold value P4, it is determined that the concentration of urea water is higher than the standard concentration (S39). This is because, as shown in FIG. 4C, the pressure drop rate of (3) with high concentration is lower than the pressure drop rates of (1) and (2) of the standard concentration. Thus, in the process of FIG. 7, the high concentration is determined when the falling start delay time is larger than the threshold T2, the rotation falling rate is smaller than the threshold R2, and the pressure falling rate is smaller than the threshold P4. . After S39, the process of FIG. 7 is ended, and the process returns to the process of FIG.

  If the pressure decrease rate is larger than the threshold value P4 in S38, it is determined that the urea water is leaking from the pipe 9 because the pressure is reduced although the pump motor 10 is rotating (S40). Thereafter, the process of FIG. 7 is ended, and the process returns to the process of FIG. The determination result such as the concentration of urea water by the process of FIG. 7, that is, the determination result of S36, S37, S39 or S40 is stored in the memory in the ECU 19. The process of FIG. 7 is a process of temporarily diagnosing the concentration or the like of urea water, and the diagnosis result is determined by the process of S8 of FIG. 5 described later.

  Returning to FIG. 5, after S7, next, based on the determination result of S5 and the determination result of S7, comprehensive determination of the concentration of urea water and the like is performed (S8). Specifically, the process of FIG. 8 is performed.

  In the process of FIG. 8, first, the determination result of S5 and the determination result of S7 are read from the memory (determination result aggregation) (S51). Next, on the basis of the judgment results collected, it is judged whether or not there is a hindrance to the continuation of the operation of the urea SCR system (S52 to S55). Specifically, it is determined whether or not there is a pipe leak determination in the aggregated determination results (S52). Since a piping leak is an abnormality that requires an emergency among system abnormalities, diagnosis is made prior to diagnosis of motor abnormality, freezing of urea water, and concentration of urea water. If there is a pipe leak determination (S52: Yes), it is finally diagnosed as a pipe leak (S53). As described above, when there is even one pipe leakage determination among the determination result of S5 and the determination result of S7, the pipe leakage is diagnosed regardless of the agreement between the determination result of S5 and the determination result of S7. After S53, the process of FIG. 8 is ended, and the process returns to the process of FIG.

  When there is no piping leak determination (S52: No), next, it is determined whether there is a determination of motor abnormality or urea water freezing among the determination results collected in S51 (S54). If there is any (S54: Yes), it is finally diagnosed as motor abnormality or urea aqueous solution freezing (S55). As described above, when there is at least one determination of motor abnormality or urea aqueous solution freezing among the determination result of S5 and the determination result of S7, the motor is determined regardless of whether the determination result of S5 and the determination result of S7 match. Diagnosed as abnormal or urea water freezing. After S55, the process of FIG. 8 is ended, and the process returns to the process of FIG.

If there is no determination of motor abnormality or urea aqueous solution freezing among the collected determination results (S54: No), it is determined that the system operation can be continued, and the concentration of urea aqueous solution is diagnosed at S56 or lower. Specifically, it is determined whether or not there is a high concentration determination among the aggregated determination results (S56). If there is any (S56: Yes), it is determined whether or not the two combined determination results, that is, the determination result of S5 and the determination result of S7, match at high concentration (S57). If they match (S57: Yes), it is finally diagnosed that the concentration of urea aqueous solution is higher than the standard concentration (S58). Thereafter, the process of FIG. 8 is ended, and the process returns to the process of FIG.

  If the two determination results do not match in S57, that is, one determination result is the high concentration determination and the other determination result is the standard concentration and the motor is normal (S57: No), the concentration determination of the urea water is not performed. It suspends in the state of determination (S61). Here, it is provisionally determined that the concentration of urea water is the standard concentration and that the pump motor 10 is operating normally, and the processing of FIG. 5 to FIG. Diagnose. Thereafter, the process of FIG. 8 is ended, and the process returns to the process of FIG.

  On the other hand, when there is no high concentration determination among the determination results collected in S56 (S56: No), next, the two determination results (the determination result in S5 and the determination result in S7) collected are the standard concentration and the motor It is judged whether it is normal and it corresponds (S59). If they match (S59: Yes), it is finally diagnosed that the concentration of urea water is the standard concentration and the pump motor 10 is operating normally (S60). On the other hand, when the two determination results do not match (S59: No), the process proceeds to S61 described above. After S60 or S61, the process of FIG. 8 is ended, and the process returns to the process of FIG.

  Referring back to FIG. 5, after S8, next, a process (system action) according to the diagnosis result of S8 is executed (S9). Specifically, when it is diagnosed as a pipe leak in S53 of FIG. 8, for example, the pump motor 10 is rotated in the reverse direction to suck back the urea water in the pipe 9 to the tank 6, and then the pump motor 10 is operated. Stop. According to this, since pumping of the urea water by the pump unit 8 is stopped, it is possible to suppress the piping leak.

  Further, in the case of a pipe leak diagnosis, for example, an alarm or the like provided in the vehicle warns that there is a possibility of a system abnormality (pipe leak). By this, it is possible to make the driver understand that there is a system abnormality, and it is possible to eliminate a pipe leakage abnormality by taking the vehicle for repair or the like.

  Further, in the case of the pipe leak diagnosis, the output of the engine 2 is limited to suppress the NOx emission (for example, the fuel injection amount is restricted so as not to perform the operation at high load). According to this, even if the urea SCR system does not function properly due to a pipe leak, the engine operation with reduced NOx emissions is performed, so the amount of NOx passing through the SCR catalyst 4 can be suppressed.

  In addition, when it is diagnosed as motor abnormality in S55 of FIG. 8, the operation of the pump motor 10 is stopped as a system action, for example, and the pumping of urea water by the pump unit 8 is stopped. By this, it can suppress that the malfunction of the pump motor 10 advances further. Further, when it is diagnosed that the motor is abnormal, for example, an alarm or output limitation of the engine 2 may be performed similarly to a piping leak.

  Further, when it is diagnosed that the urea aqueous solution is frozen in S55 of FIG. 8, for example, the heaters 13 and 14 (see FIG. 2) are energized to perform control to thaw the urea aqueous solution as a system action. After this control (heater energization) is continued for a predetermined time, the processing of FIGS. 5 to 8 is performed again to rediagnose the presence or absence of freezing of the urea water. By this, it can control that system operation is carried out with freezing. Further, when it is diagnosed that the urea aqueous solution is frozen, for example, an alarm or the output restriction of the engine 2 may be performed similarly to the piping leak.

  Further, when it is diagnosed in S58 of FIG. 8 that the concentration is high, for example, as a system action, the addition amount of urea water by the injector 5 is reduced from the addition amount at the standard concentration. As a result, excessive supply of urea (ammonia) to the SCR catalyst 4 can be suppressed, and as a result, ammonia slip can be suppressed and waste of urea water can be suppressed. In addition, when it is diagnosed as high concentration, it may be warned that high concentration urea water is used. Thus, for example, by resupplying a standard concentration of urea water, it is possible to suppress the continued use of high concentration urea water.

  If it is determined at S60 in FIG. 8 that the standard concentration and the motor are normal, the normal operation of the system is continued. Further, if it is determined in S61 that rediagnosis management is performed, the concentration or the like of the aqueous urea solution is rediagnosed as described above. After S9, the process of FIG. 5 ends.

  As mentioned above, according to this embodiment, even if it does not use the sensor which detects the quality of urea water, system abnormalities, such as the concentration of urea water and freezing, can be diagnosed. It is possible to diagnose piping leaks, motor abnormalities, and freezing of urea water as system abnormalities. Further, by observing the rotational behavior of the pump motor 10 and the pressure behavior of the pipe 9, it is possible to detect the freezing of the urea water that is actually sucked and discharged by the pump unit 8 in a short time. For example, when only a part of the urea aqueous solution in the tank 6 is frozen, when the pump unit 8 sucks in the frozen urea aqueous solution, it can be determined that the urea aqueous solution is frozen, and the non-freeze urea aqueous solution is pumped When 8 is inhaled, it can be determined that the urea water is not frozen.

  In addition, the temporary diagnosis result (result of S5) at the time of motor energization start and the temporary diagnosis result (result of S7) at the time of motor energization stop are integrated to comprehensively diagnose the concentration of urea water and system abnormality. , Its diagnostic accuracy can be improved. In the comprehensive diagnosis, if even one of the two provisional diagnosis results has a system abnormality result, the system abnormality is adopted as the final diagnosis result, so that omission in detection of the system abnormality can be suppressed. Also, in the comprehensive diagnosis, when two temporary diagnostic results coincide with each other at the same concentration, the corresponding concentration is adopted as a final diagnostic result, while when the two temporary diagnostic results differ from each other, This diagnosis can improve the accuracy of concentration diagnosis without determining the concentration.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the claims. For example, although the example which diagnoses the concentration of urea water was shown in the above-mentioned embodiment, you may diagnose the viscosity of urea water instead of a concentration. That is, as shown in FIG. 3, the viscosity in the case of high concentration (for example 40%) is higher than the viscosity in the case of standard concentration (for example 32.5%). The standard concentration may be replaced with the standard viscosity, and the high concentration may be replaced with the high viscosity.

  Further, in the above embodiment, the concentration of urea water and the system abnormality are diagnosed based on the rotational behavior and pressure behavior at the start of motor energization, but control for changing the rotational speed further during steady rotation of the motor It may be carried out and diagnosis of urea aqueous solution concentration or system abnormality may be made based on the rotational behavior and pressure behavior at that time.

  Further, in the above embodiment, the concentration of urea water and the system abnormality are diagnosed based on the rotational behavior and pressure behavior at the time of motor power off, but control to lower the motor rotational speed while continuing the motor power You may diagnose the concentration of urea water or system abnormality based on the rotational behavior and pressure behavior at that time.

  Further, in the above embodiment, the rising control for changing the motor rotation number in the increasing direction and the lowering control for changing the motor rotation number in the decreasing direction are executed. It is good. At this time, for example, in the case where both of the lift controls are executed, the contents of one lift control and the other lift control are made different. Specifically, for example, one rise control is set to motor energization start control, and the other rise control is set to control to further increase the motor rotational speed during motor energization. Also by this, the diagnostic accuracy can be improved by integrating the temporary diagnosis result at the time of one rise control and the temporary diagnosis result at the other time of the rise control to perform comprehensive diagnosis.

  In the above embodiment, two temporary diagnoses at the time of motor energization start and stop are performed. However, three or more temporary diagnoses are performed, and the obtained temporary diagnoses are integrated to perform comprehensive diagnosis. May be implemented. At this time, for example, a majority decision among a plurality of provisional diagnosis results determines which diagnosis result is finally adopted. This can further improve the diagnostic accuracy.

  Further, in the above embodiment, two levels of standard concentration or high concentration were diagnosed as urea aqueous solution concentration diagnosis, but three or more levels of concentration may be diagnosed. As an example of the three levels of concentration diagnosis, for example, it may be diagnosed whether the concentration is lower than the standard concentration, the standard concentration, or the concentration higher than the standard concentration. At this time, as shown in FIG. 3, when the concentration is lower than the standard concentration (32.5%), the viscosity slightly decreases, and when the viscosity decreases, the rotational behavior of the motor and the pressure behavior of the pipe have a standard concentration. The behavior changes (e.g. the rotation start delay time is even shorter than in the case of the standard concentration). By capturing the difference between the rotational behavior and the pressure behavior, it is possible to determine a lower concentration than the standard concentration.

  Further, the diagnosis at the motor energization stop may be omitted, only the diagnosis at the motor energization start may be performed, and the diagnosis result may be adopted as the final diagnosis result. That is, in FIG. 5, S6 to S8 may be omitted, and the diagnosis result of S5 may be adopted as the final diagnosis result as it is. This can simplify the diagnosis.

  Similarly, the diagnosis at the start of the motor energization may be omitted, and only the diagnosis at the motor energization stop may be performed, and the diagnosis result may be adopted as the final diagnosis result. That is, in FIG. 5, S5 and S8 may be omitted, and the diagnosis result of S7 may be adopted as the final diagnosis result as it is.

6 Tank 8 Pump Unit 9 Piping 10 Pump Motor 19 ECU (Diagnostic Device)

Claims (14)

A tank (6) for storing urea water,
A pump (8) for sucking in and discharging urea water stored in the tank;
The invention is applied to a urea water supply system including a pipe (9) for leading urea water discharged from the pump to the injector,
A motor control unit (S4, S6) for performing control to change a rotational state of a motor (10) of the pump;
A rotational behavior acquisition unit (S11, S31) for acquiring a rotational behavior of the motor at the time of performing the control;
A pressure behavior acquisition unit (S11, S31) for acquiring pressure behavior in the pipe at the time of execution of the control;
A diagnosis unit (S12 to S20, S32 to S40, S8) that diagnoses the concentration or viscosity of urea water based on the rotational behavior and the pressure behavior and an abnormality of the urea water supply system;
Equipped with
The motor control unit executes the control a plurality of times of changing to different rotation states.
The rotation behavior acquisition unit acquires the rotation behavior for each control of each time,
The pressure behavior acquisition unit acquires the pressure behavior for each time of the control,
The diagnostic unit
Based on the rotational behavior and the pressure behavior acquired in the same control, temporary diagnosis of the concentration or viscosity of the aqueous urea solution and the abnormality of the aqueous urea solution supply system is performed, and the temporary diagnosis is performed for each of the individual control operations Temporary diagnosis units (S12 to S20, S32 to S40) to be implemented;
The integrated diagnosis unit (S8) is configured to diagnose the concentration or viscosity of urea water and an abnormality of the urea aqueous solution supply system by collecting the temporary diagnosis results by the temporary diagnosis unit.
The motor control unit
A lift control unit (S4) that performs lift control to change the rotation speed of the motor in the direction to increase the rotation speed;
And a lowering control unit (S6) for performing a lowering control to change the number of rotations of the motor in the direction of decreasing the number of rotations.
The rotation behavior acquisition unit
A rotation rising behavior acquisition unit (S11) for acquiring a rotation rising behavior that is a rotation behavior of the motor at the time of performing the rising control;
And d) a rotation descent behavior acquisition unit (S31) for acquiring a rotation descent behavior, which is a rotation behavior of the motor at the time of the descent control.
The pressure behavior acquisition unit
A pressure rise behavior acquisition unit (S11) that acquires a pressure rise behavior that is a pressure behavior of the motor at the time of execution of the rise control;
And a pressure drop behavior acquiring unit (S31) for acquiring a pressure drop behavior which is a pressure behavior of the motor at the time of execution of the drop control.
The temporary diagnosis unit
A first diagnosis unit (S12 to S20) that temporarily diagnoses the concentration or viscosity of urea water and an abnormality of the urea water supply system based on the rotation rising behavior and the pressure rising behavior;
A second diagnosis unit (S32 to S40) for temporarily diagnosing the concentration or viscosity of urea water and an abnormality of the urea water supply system based on the rotation lowering behavior and the pressure lowering behavior;
The comprehensive diagnosis unit is a diagnosis that diagnoses the concentration or viscosity of urea water and an abnormality of the urea water supply system based on the provisional diagnosis result by the first diagnosis unit and the provisional diagnosis result by the second diagnosis unit. Device (19). The integrated diagnosis unit adopts the abnormality as a final diagnosis result when any one of the plurality of temporary diagnosis results by the temporary diagnosis unit indicates the abnormality of the urea aqueous solution supply system. The diagnostic device according to claim 1 , comprising an abnormality diagnosis unit (S52 to S55). The comprehensive diagnosis unit sets the urea water concentration or viscosity as the final diagnosis result only when all of the plurality of temporary diagnosis results by the temporary diagnosis unit indicate the same urea water concentration or viscosity. The diagnostic device according to claim 1 or 2 , further comprising a concentration diagnostic unit (S56 to S61) to be employed. If the diagnosis unit (S17, S20, S37, S40, S52 to S55) diagnoses that the urea water supply system is abnormal, does it correspond to a leak of urea water from the piping, or the urea water? The diagnostic device according to any one of claims 1 to 3, wherein it is diagnosed whether it corresponds to the freezing of the motor or the abnormality of the motor. When the diagnostic unit (S16, S19, S36, S39, S58, S60) diagnoses the concentration or viscosity of aqueous urea, whether it is the standard concentration or viscosity assumed by the aqueous urea supply system or not The diagnostic device according to any one of claims 1 to 4, which diagnoses whether the concentration or viscosity is higher than the standard concentration or viscosity. The rotational behavior acquisition unit uses, as the rotational behavior, a delay time from the start of the control to the start of change in the rotational speed of the motor, and a rate of change of rotational speed with respect to time in the process of changing the rotational speed of the motor The diagnostic device according to any one of claims 1 to 5, wherein The diagnostic device according to any one of claims 1 to 6, wherein the pressure behavior acquisition unit acquires, as the pressure behavior, a rate of change in pressure in the pipe with respect to time since the start of the control. A tank (6) for storing urea water,
A pump (8) for sucking in and discharging urea water stored in the tank;
The invention is applied to a urea water supply system including a pipe (9) for leading urea water discharged from the pump to the injector,
A motor control unit (S4, S6) for performing control to change a rotational state of a motor (10) of the pump;
A rotational behavior acquisition unit (S11, S31) for acquiring a rotational behavior of the motor at the time of performing the control;
A pressure behavior acquisition unit (S11, S31) for acquiring pressure behavior in the pipe at the time of execution of the control;
A diagnosis unit (S12 to S20, S32 to S40, S8) that diagnoses the concentration or viscosity of urea water based on the rotational behavior and the pressure behavior and an abnormality of the urea water supply system;
Equipped with
The motor control unit includes a lift control unit (S4) that performs lift control to change the rotational speed of the motor in a direction to increase the number of rotations.
The rotation behavior acquisition unit includes, as the rotation behavior, a rise start delay time from the start of the rise control to the start of the rise in the motor rotation speed, and a rotation speed with respect to time in the process of increasing the motor rotation speed. A rotation rising behavior acquisition unit (S11) for acquiring the
The pressure behavior acquisition unit includes a pressure rise behavior acquisition unit (S11) that acquires, as the pressure behavior, a rate of increase in pressure in the pipe with respect to time since the start of the rise control.
The diagnosis unit determines that the urea aqueous solution is abnormal when the rising start delay time is larger than a threshold, the rate of increase of the rotational speed is smaller than a threshold, and the rate of increase of the pressure is smaller than a threshold. A diagnostic device (19) including a motor abnormality / freeze diagnosis unit (S20) that diagnoses as motor abnormality or urea water freezing . When the rising start delay time is larger than the threshold, the rate of increase of the rotational speed is smaller than the threshold, and the rate of increase of the pressure is larger than the threshold, the diagnostic unit determines the concentration or viscosity of the aqueous urea The diagnostic device according to claim 8 , further comprising a high concentration diagnostic unit (S19) that diagnoses that the concentration or viscosity is higher than the standard concentration or viscosity assumed by the aqueous urea solution supply system. At least one of the rising start delay time being smaller than the threshold and / or the rising rate of the rotational speed being larger than the threshold is satisfied, and the diagnostic unit holds the rising rate of the pressure smaller than the threshold. The diagnostic device according to claim 8 or 9 , further comprising: a pipe leak diagnosis unit (S17) that diagnoses that the urea water is leaking from the pipe as an abnormality of the urea water supply system. At least one of the rising start delay time being smaller than the threshold and / or the rising rate of the rotational speed being larger than the threshold is satisfied, and the diagnostic unit is configured to set the rising rate of the pressure higher than the threshold. The diagnosis according to any one of claims 8 to 10, further comprising: a standard concentration diagnostic unit (S16) that diagnoses that the concentration or viscosity of the aqueous urea solution is the standard concentration or viscosity assumed by the aqueous urea solution supply system. apparatus. A tank (6) for storing urea water,
A pump (8) for sucking in and discharging urea water stored in the tank;
The invention is applied to a urea water supply system including a pipe (9) for leading urea water discharged from the pump to the injector,
A motor control unit (S4, S6) for performing control to change a rotational state of a motor (10) of the pump;
A rotational behavior acquisition unit (S11, S31) for acquiring a rotational behavior of the motor at the time of performing the control;
A pressure behavior acquisition unit (S11, S31) for acquiring pressure behavior in the pipe at the time of execution of the control;
A diagnosis unit (S12 to S20, S32 to S40, S8) that diagnoses the concentration or viscosity of urea water based on the rotational behavior and the pressure behavior and an abnormality of the urea water supply system;
Equipped with
The motor control unit includes a lowering control unit (S6) that performs lowering control to change the number of rotations of the motor in the direction of decreasing the number of rotations.
The rotation behavior acquisition unit includes, as the rotation behavior, a fall start delay time from when the fall control is started to when the fall of the rotation speed of the motor starts, and a rotation speed with respect to time in the process of falling the rotation speed of the motor And a descent rate acquisition unit (S31) for acquiring the descent rate of
The pressure behavior acquisition unit includes, as the pressure behavior, a pressure decrease behavior acquisition unit (S31) that acquires a decrease rate of the pressure in the pipe with respect to the time after the start of the decrease control.
The diagnostic unit is configured to determine that the descent start delay time is greater than the threshold and the descent rate of the rotational speed is smaller than the threshold and the descent rate of the pressure is greater than the threshold, or the descent start delay time is greater than the threshold At least one of the fact that the rate of decrease of the rotational speed is greater than the threshold value and at least one of the rate of decrease of the pressure is greater than the threshold, urea water from the piping is identified as an abnormality of the urea water supply system. Diagnostic apparatus (19) provided with piping leak diagnostic part (S37, S40) which diagnoses as having leaked . The diagnostic unit determines that the concentration or the viscosity of the aqueous urea solution is the same as that of the urea aqueous solution, when the falling start delay time is larger than the threshold, the falling rate of the rotation speed is smaller than the threshold, and the falling rate of the pressure is smaller than the threshold. The diagnostic device according to claim 12 , further comprising a high concentration diagnostic unit (S39) that diagnoses that the concentration or viscosity is higher than the standard concentration or viscosity assumed by the aqueous urea solution supply system. At least one of the fact that the falling start delay time is smaller than the threshold and / or the falling rate of the rotational speed is larger than the threshold is satisfied, and the diagnostic unit determines that the pressure falling rate is smaller than the threshold. The diagnostic device according to claim 12 or 13 , further comprising a standard concentration diagnostic unit (S36) that diagnoses that the concentration or viscosity of water is a standard concentration or viscosity assumed by the aqueous urea solution supply system.

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