JP2016156301A - Control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a diesel engine capable of reducing trouble caused by freezing of a throttle valve.SOLUTION: An ECU 50 includes a memory 51 for holding freezing condition data 60 specifying an intake temperature and a cooling water temperature as a freezing condition of a throttle valve 30, an acquiring section 52 for acquiring a detection value of an intake temperature sensor 35 and a cooling water temperature sensor 36, a determination section 53 for determining satisfaction/non-satisfaction of the freezing condition, and a throttle control section 55 for controlling an opening of the throttle valve 30. The ECU 50 determines satisfaction/non-satisfaction of the freezing condition when an engine 10 is stopped, and stops the engine 10 by controlling the throttle valve 30 to be fully closed when the freezing condition is not satisfied, and stops the engine 10 without controlling the throttle valve 30 to be fully closed when the freezing condition is satisfied.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a diesel engine having a throttle valve in an intake passage.

  In recent years, a diesel engine having a throttle valve for controlling the intake air amount in an intake passage has been put into practical use. For example, in Patent Document 1, the throttle valve is normally controlled to be in an open state, and is controlled to be in a fully closed state when the engine is stopped. The intake air is blocked by the control to the fully closed state, thereby realizing an early stop of the engine while suppressing the vibration of the engine.

Japanese Patent Laid-Open No. 10-30457

  By the way, in a low temperature environment, the throttle valve may stick due to freezing. Therefore, for example, when the throttle valve is controlled to be fully closed when the engine is stopped as in Patent Document 1, the throttle valve may freeze in the fully closed state. If this frozen state continues until the next engine start, there is a risk that smooth engine start may be hindered due to a shortage of intake air.

  An object of this invention is to provide the control apparatus of the diesel engine which reduces the malfunction resulting from freezing of a throttle valve.

  A control device for a diesel engine that solves the above-described problem is an acquisition unit that acquires an intake air temperature that is a temperature of intake air and a cooling water temperature that is a temperature of engine cooling water, and determines whether a freezing condition in which the throttle valve is frozen is successful A determination unit for controlling the throttle valve, and a throttle control unit for controlling the opening of the throttle valve. The freezing condition is that the intake air temperature is equal to or lower than a first determination value and the cooling water temperature is equal to or lower than a second determination value. The determination unit determines whether or not the freezing condition is satisfied when the engine is stopped, and the throttle control unit controls the throttle valve to be fully closed when the freezing condition is not satisfied, When the freezing condition is satisfied, the throttle valve is controlled to be opened.

  According to the above configuration, when the freezing condition is not satisfied when the engine is stopped, the engine is stopped after the throttle valve is controlled to be fully closed, and when the freezing condition is satisfied when the engine is stopped, the throttle valve is opened. Stops. As a result, it is possible to prevent the throttle valve from freezing in the fully closed state when the engine is stopped, and to smoothly start the engine next time. As a result, it is possible to reduce problems caused by freezing of the throttle valve.

  The control device for the diesel engine further includes an intake air temperature sensor that detects the intake air temperature, and an abnormality detection unit that detects an abnormality in the cooling water temperature sensor that detects the cooling water temperature, and the throttle control unit includes: When the abnormality detection unit detects an abnormality in at least one of the intake air temperature sensor and the cooling water temperature sensor, it is preferable to maintain the throttle valve in an open state.

  According to the above configuration, when an abnormality is detected in at least one of the intake air temperature sensor and the cooling water temperature sensor, that is, when the reliability for the success or failure of the freezing condition is low, the throttle valve is maintained in the open state. Thereby, even when an abnormality occurs in each sensor, it is possible to prevent the throttle valve from freezing in the fully closed state when the engine is stopped.

  The control device of the diesel engine further includes a sticking detection unit that detects sticking of the throttle valve, and the acquisition unit calculates a detection opening that is an opening of the throttle valve based on an input signal from a throttle position sensor. The sticking detection unit detects sticking of the throttle valve by comparing an instruction opening degree with respect to the throttle valve and a detection opening degree of the throttle position sensor, and the judgment unit detects the sticking of the throttle valve during operation of the engine. It is preferable to determine whether or not the freezing condition is satisfied and to determine that the throttle valve is in a frozen state when the sticking detection unit detects sticking of the throttle valve in a state where the freezing condition is met.

  According to the above configuration, the determination unit determines that the throttle valve is in a frozen state when the sticking of the throttle valve is detected while the freezing condition is satisfied. This makes it possible to determine whether or not the throttle valve is stuck due to freezing.

  The control device for a diesel engine further includes a warning control unit that controls a warning unit that warns a driver that the throttle valve is stuck, and the warning control unit includes the warning unit when the throttle valve is in a frozen state. It is preferable to control to an inoperative state.

  The sticking of the throttle valve due to freezing is an abnormality of the throttle valve, but is eliminated by thawing the throttle valve, and is not an abnormality that requires replacement or repair of the throttle valve. According to the above configuration, when the throttle valve is stuck due to freezing, the warning unit is controlled to be inactive. As a result, misjudgment regarding the abnormality of the throttle valve can be suppressed, so that problems caused by freezing of the throttle valve can be reduced.

  The control device for a diesel engine further includes an EGR control unit that controls an EGR valve provided in an EGR passage that connects an exhaust passage and an intake passage of the engine, and the EGR control unit is configured such that the throttle valve is in a frozen state. It is preferable to control the EGR valve to a fully closed state.

  According to the above configuration, when the throttle valve is frozen, that is, when the intake air amount cannot be adjusted by the opening degree of the throttle valve, the EGR valve is controlled to be fully closed. Thereby, since only the intake air is supplied to the engine, the generation of black smoke and the decrease in engine output due to the shortage of the intake air can be suppressed. As a result, it is possible to reduce problems caused by freezing of the throttle valve.

It is a figure which shows schematic structure of the engine system carrying the control apparatus of the diesel engine of one Embodiment. It is a graph which shows an example of the result of the experiment conducted in order to set freezing conditions, Comprising: It is a graph which shows the relationship between intake air temperature and cooling water temperature. It is a graph which shows an example of the result of the experiment conducted in order to set freezing conditions, Comprising: It is a graph which shows the relationship between intake air temperature and valve | bulb temperature. It is a flowchart which shows an example of a freezing determination process. It is a flowchart which shows an example of a mode selection process. It is a flowchart which shows an example of a stop process. It is a flowchart which shows an example of a sensor abnormality process.

  With reference to FIGS. 1-7, one Embodiment of the control apparatus of a diesel engine is described. First, an overall configuration of an engine system equipped with a diesel engine control device will be described with reference to FIG.

  As shown in FIG. 1, the engine system includes a diesel engine 10 (hereinafter referred to as an engine 10). The cylinder block 11 of the engine 10 is formed with six cylinders 12 arranged in a row. Fuel is injected into each cylinder 12 from an injector 13. Connected to the cylinder block 11 are an intake manifold 14 for supplying intake air to each cylinder 12 and an exhaust manifold 15 into which exhaust gas from each cylinder 12 flows.

  In the intake passage 16 connected to the intake manifold 14, an air cleaner (not shown), a compressor 18 constituting a turbocharger 17, and an intercooler 19 are provided in order from the upstream side. The exhaust passage 20 connected to the exhaust manifold 15 is provided with a turbine 22 that is connected to the compressor 18 via a connecting shaft and constitutes the turbocharger 17.

  The engine system includes an EGR passage 25 that connects the exhaust manifold 15 and the intake passage 16. The EGR passage 25 is provided with an EGR cooler 26 and an EGR valve 27 on the side of the intake passage 16 with respect to the EGR cooler 26 that can change the flow path cross-sectional area of the EGR passage 25. When the EGR valve 27 is in an open state, a part of the exhaust gas is introduced into the intake passage 16 through the EGR passage 25 as EGR gas.

  Further, the engine system includes a throttle valve 30 in the intake passage 16 downstream of the intercooler 19 and upstream of the connection portion of the EGR passage 25 with respect to the intake passage 16. The throttle valve 30 is an electronically controlled butterfly valve that is pivotally supported by a butterfly shaft, and is configured so that the cross-sectional area of the intake passage 16 can be changed. When the throttle valve 30 is in the open state, intake air can be supplied to the cylinder 12. On the other hand, when the throttle valve 30 is in the fully closed state, the supply of intake air to the cylinder 12 is shut off.

  That is, when the throttle valve 30 is in the open state and the EGR valve 27 is in the open state, the cylinder 12 is supplied with a mixed gas of intake air and EGR gas as the working gas. When the throttle valve 30 is in an open state and the EGR valve 27 is in a fully closed state, only intake air is supplied to the cylinder 12 as a working gas. The throttle valve 30 is controlled to be in an open state except for a period during which the engine 10 is stopped, except that the throttle valve 30 is temporarily controlled to be fully closed when the engine 10 is stopped. Therefore, when the throttle valve 30 is frozen other than when the engine 10 is stopped, the throttle valve 30 is fixed in an open state.

  The engine system includes various sensors. The engine system includes an intake air temperature sensor 35 that detects an intake air temperature Ta, which is the temperature of intake air, upstream of the compressor 18 in the intake passage 16. The engine system includes a coolant temperature sensor 36 that detects a coolant temperature Tw that is a temperature of engine coolant that cools the engine 10. The engine system includes a throttle position sensor 37 that detects a detected opening VT that is the opening of the throttle valve 30. These sensors 35, 36, and 37 output signals indicating the detected values to the ECU 50.

  The engine system also includes an operation unit 41 that is operated by the driver when the engine 10 is started and stopped. The operation unit 41 outputs a signal indicating the start of the engine 10 or the stop of the engine 10 to the ECU 50 according to the operation of the driver. Further, the engine system is controlled to be in an operating state when an abnormality such as, for example, the stuck throttle valve 30 is detected in the engine system, and a warning light 42 is provided to warn the driver that an abnormality has occurred in the engine system. I have.

  The ECU 50 performs overall control of the engine system described above. The ECU 50 is configured by a microcomputer and has a memory 51 including a ROM that stores various data such as various control programs and freezing conditions, and a RAM that temporarily stores calculation results and various data in various calculations. . The ECU 50 performs various controls according to various control programs and various data stored in the memory 51.

  The freezing condition data 60 stored in the memory 51 is data indicating a freezing condition in which the throttle valve 30 is frozen or the throttle valve 30 is likely to be frozen. Regarding the intake air temperature Ta and the cooling water temperature Tw It is prescribed.

  The acquisition unit 52 of the ECU 50 acquires the intake air temperature Ta detected by the intake air temperature sensor 35, the coolant temperature Tw detected by the coolant temperature sensor 36, and the detected opening VT detected by the throttle position sensor 37. To do.

  The determination unit 53 of the ECU 50 determines the success or failure of the freezing condition based on the intake air temperature Ta and the coolant temperature Tw acquired by the acquisition unit 52. Further, the determination unit 53 determines whether or not the throttle valve 30 is in a frozen state when the freezing condition is satisfied during operation of the engine 10.

  The mode selection unit 54 of the ECU 50 selects the control mode of the throttle valve 30 and the EGR valve 27 according to whether or not the throttle valve 30 is in a frozen state. The mode selection unit 54 selects the normal mode when the throttle valve 30 is not frozen, and selects the EGR cut mode when the throttle valve 30 is frozen.

  The throttle control unit 55 of the ECU 50 controls the opening of the throttle valve 30 based on the operating state of the engine 10 in the normal mode, and maintains the throttle valve 30 in an open state without controlling the throttle valve 30 in the EGR cut mode. The throttle control unit 55 performs full-open control for controlling the throttle valve 30 to a fully open state when the freezing condition is satisfied when the engine is stopped in the normal mode, and performs shutter control for the throttle valve 30 when the freezing condition is not satisfied. . In the shutter control, the throttle control unit 55 once controls the throttle valve 30 to a fully closed state, and then controls the throttle valve 30 to a predetermined starting opening degree immediately before the engine 10 is stopped.

The EGR control unit 56 of the ECU 50 controls the opening degree of the EGR valve 27 based on the engine operating state in the normal mode, and controls the EGR valve 27 to the fully closed state in the EGR cut mode.
The sticking detection unit 57 of the ECU 50 includes a trial instruction opening tVTcom output to the throttle valve 30 through the throttle control unit 55 to detect the presence of sticking, and a detected opening VT immediately after the trial instruction opening tVTcom is output. The sticking of the throttle valve 30 is detected on the basis of the deviation ΔVT. The sticking detector 57 detects sticking of the throttle valve 30 when the deviation ΔVT is smaller than the threshold value ΔVTth.

The abnormality detection unit 58 of the ECU 50 detects an abnormality in the detection value of the intake air temperature sensor 35 and an abnormality in the detection value of the cooling water temperature sensor 36.
The warning control unit 59 of the ECU 50 controls the warning lamp 42 to the operating state, that is, the lighting state when the sticking detection unit 57 detects the sticking of the throttle valve 30. The warning control unit 59 turns off the warning light 42 when the determination unit 53 determines that the throttle valve 30 is in a frozen state even when the adhesion detection unit 57 detects the adhesion of the throttle valve 30. It controls to an operation state, ie, a non-lighting state. The warning control unit 59 controls the warning lamp 42 to turn on when an abnormality is detected in at least one of the intake air temperature sensor 35 and the coolant temperature sensor 36.

  The ECU 50 controls whether the throttle control unit 55 controls the throttle valve 30, the EGR control unit 56 controls the EGR valve 27, and the warning control unit 59 controls the warning light 42 based on whether or not the freezing condition stored in the ROM is one condition. Take control. The freezing condition is a condition indicating that the throttle valve 30 is frozen or that the possibility that the throttle valve 30 is frozen is high. The throttle valve 30 is cooled by the outside air, and is heated by the radiant heat of the engine 10. Therefore, the freezing condition is defined for the intake air temperature Ta, which is a parameter related to the outside air temperature, and the cooling water temperature Tw, which is a parameter related to the radiant heat of the engine 10. The freezing condition includes a first determination value Ta1 indicating a condition for the intake air temperature Ta and a second determination value Tw2 indicating a condition for the cooling water temperature Tw.

  The first determination value Ta1 and the second determination value Tw2 are set based on the results of experiments performed on the actual engine of the engine system shown in FIG. This is because the radiant heat of the engine 10 received by the throttle valve 30 differs depending on the positional relationship between the throttle valve 30 and the engine 10 and the piping located between the throttle valve 30 and the engine 10. . Further, the detected values of the intake air temperature sensor 35 and the cooling water temperature sensor 36 also differ depending on the mounting position. In this experiment, in addition to the intake air temperature sensor 35 and the coolant temperature sensor 36, a sensor for detecting the valve temperature Tv, which is the temperature of the throttle valve 30, was attached to the throttle valve 30. Then, the freezing condition was set based on the cooling water temperature Tw obtained by driving the engine system under each intake air temperature Ta and the valve temperature Tv while maintaining the EGR valve 27 in the fully closed state. Note that the valve temperature Tv at which the throttle valve 30 in the frozen state melts and the throttle valve 30 becomes operable is called the ice melting temperature. In this experiment, the ice melting temperature was set to 5 ° C.

  FIG. 2 is a graph showing the relationship between the intake air temperature Ta and the coolant temperature Tw in the engine system. This graph shows the cooling water temperature Twa when the valve temperature Tv reaches the ice melting temperature when the engine 10 is cold-started under each intake air temperature Ta. As shown in FIG. 2, the cooling water temperature Twa is higher than the warm-up completion temperature (for example, 40 ° C.) of the engine 10 and is about 55 ° C. when the intake air temperature Ta is −5 ° C., and the intake air temperature Ta is − The temperature was about 57.5 ° C. at 10 ° C. and about 60 ° C. when the intake air temperature Ta was −18 ° C.

  FIG. 3 is a graph showing the relationship between the intake air temperature Ta and the valve temperature Tv in the engine system. This graph shows the valve temperature Tv when the cooling water temperature Twa is maintained under each intake air temperature Ta. As shown in FIG. 3, the valve temperature Tv is about 8.1 ° C. when the intake air temperature Ta is −5 ° C., and is about 6.3 ° C. when the intake air temperature Ta is −10 ° C. It was about 5.2 ° C. when Ta was −18 ° C.

  The first determination value Ta1 and the second determination value Tw2 are set based on these experimental data. The present inventor sets -21 ° C. as the first determination value Ta1 and 62 ° C. as the second determination value Tw2 in consideration of variations of the sensors. That is, the freezing condition is satisfied when the intake air temperature Ta is a temperature that is equal to or lower than the first determination value Ta1 and the cooling water temperature Tw is equal to or lower than the second determination value Tw2. As described above, the environment of the throttle valve 30 is different depending on, for example, the positional relationship between the engine 10 and the throttle valve 30, and therefore the first determination value Ta1 and the second determination value Tw2 are not limited to the above-described values.

Next, control of the throttle valve 30 by the throttle control unit 55 and control of the EGR valve 27 by the EGR control unit 56 will be described from when the engine 10 is started.
The ECU 50 starts the engine 10 when a start signal is input from the operation unit 41. As will be described in detail later, when the engine 10 is started, the throttle valve 30 is open and the EGR valve 27 is fully closed. When the coolant temperature Tw, which is a detected value of the coolant temperature sensor 36 at the start of the engine 10, is less than the warm-up completion temperature, the EGR control unit 56 performs the EGR valve until the coolant temperature Tw reaches the warm-up completion temperature. 27 is maintained in a fully closed state, and the throttle control unit 55 maintains the throttle valve 30 at the opening when the engine is started.

  When the coolant temperature Tw reaches the warm-up completion temperature, and when the coolant temperature Tw is equal to or higher than the warm-up completion temperature when the engine 10 is started, the ECU 50 repeatedly executes the freeze determination process and the mode selection process. The freeze determination process is a process for determining whether or not the throttle valve 30 is frozen during operation of the engine 10. The mode selection process is a process of selecting the control mode of the throttle valve 30 and the EGR valve 27 during the operation of the engine 10 according to the determination result of the freezing determination process. The throttle control unit 55 and the EGR control unit 56 control the throttle valve 30 and the EGR valve 27 in the control mode selected in the mode selection process.

  The freezing determination process will be described with reference to FIG. As shown in FIG. 4, in the freezing determination process, first, the acquisition unit 52 of the ECU 50 first detects the intake air temperature Ta detected by the intake air temperature sensor 35 and the coolant temperature Tw detected by the coolant temperature sensor 36. Is acquired (step S11). Next, the determination unit 53 of the ECU 50 determines whether or not the freezing condition is satisfied, that is, the intake air temperature Ta is equal to or lower than the first determination value Ta1, and the cooling water temperature Tw is equal to or lower than the second determination value Tw2. It is determined whether or not both of these are established (step S12). When the freezing condition is satisfied (step S12: YES), the sticking detection unit 57 of the ECU 50 determines whether or not the throttle valve 30 is actually stuck.

  In the next step S <b> 13, the sticking detection unit 57 outputs a trial instruction opening tVTcom, which is an opening changed by a predetermined amount from the latest detection opening VT, to the throttle valve 30 through the throttle control unit 55. Next, the sticking detection unit 57 calculates a deviation ΔVT between the trial instruction opening tVTcom and the detected opening VT immediately after the trial instruction opening tVTcom is output based on the signal from the throttle position sensor 37 (step S14). . Then, the sticking detection unit 57 compares the deviation ΔVT with the threshold value ΔVTth (step S15).

  When deviation ΔVT is less than threshold value ΔVTth (step S15: YES), sticking detector 57 detects sticking of throttle valve 30. The determination unit 53 determines that the throttle valve 30 is in a frozen state when the sticking of the throttle valve 30 is detected in a state where the freezing condition is satisfied (step S16). If it is determined that the throttle valve 30 is in a frozen state, the warning control unit 59 controls the warning lamp 42 to be in a non-lighted state although the throttle valve 30 is fixed (step S17). As a result, a series of processing is temporarily ended.

  On the other hand, when the freezing condition is not satisfied (step S12: NO) and when the deviation ΔVT is greater than or equal to the threshold value ΔVTth (step S15: NO), the determination unit 53 determines that the throttle valve 30 is in the non-freezing state (step). S18). As a result, a series of processing is temporarily ended.

  The sticking of the throttle valve 30 due to freezing is an abnormality of the throttle valve 30, but is eliminated by thawing of the throttle valve 30, so that it is not an abnormality that requires replacement or repair of the throttle valve 30, for example. For this reason, if the warning light 42 is turned on even when the throttle valve 30 is fixed due to freezing, the driver is forced to perform extra confirmation work. In this regard, according to the above-described freezing determination process, if the throttle valve 30 is stuck due to freezing, the warning lamp 42 is controlled to be in a non-lighted state (step S17), so that an erroneous determination regarding abnormality of the throttle valve 30 is made. Can be suppressed. The ECU 50 continuously determines whether or not the throttle valve 30 is frozen while repeatedly performing such a freezing determination process while suppressing erroneous determination of abnormality of the throttle valve 30.

  The mode selection process will be described with reference to FIG. As shown in FIG. 5, in the mode selection process, the mode selection unit 54 of the ECU 50 determines whether or not the throttle valve 30 is in a frozen state based on the determination result of the freezing determination process (step S21). When the throttle valve 30 is in a frozen state (step S21: YES), the mode selection unit 54 selects the EGR cut mode (step S22). In the EGR cut mode, the throttle controller 55 maintains the throttle valve 30 in an open state by interrupting the control of the throttle valve 30, and the EGR controller 56 controls the EGR valve 27 in a fully closed state.

  On the other hand, when the throttle valve 30 is in the non-freezing state (step S21: NO), the mode selection unit 54 selects the normal mode (step S23). In the normal mode, the throttle control unit 55 and the EGR control unit 56 set the throttle valve 30 and the EGR valve 27 so that the working gas having an EGR rate suitable for the operating state of the engine 10 is supplied to the cylinder 12. Control.

  Although the throttle valve 30 in the frozen state is fixed in the open state, depending on the opening degree of the throttle valve 30 at the time of freezing, the intake air becomes insufficient due to the introduction of EGR gas, and black smoke is likely to be generated. Or drop. As described above, the ECU 50 switches the control of the EGR valve 27 according to whether or not the throttle valve 30 is frozen (step S21). Then, when the throttle valve 30 is in a frozen state, the ECU 50 selects the EGR cut mode and controls the EGR valve 27 to a fully closed state (step S22). Thereby, only intake air is supplied to the cylinder 12 as working gas. As a result, the shortage of intake air is suppressed, so that even if the throttle valve 30 is fixed in the open state, the generation of black smoke and the decrease in engine output can be suppressed.

  The stop process of the engine 10 will be described with reference to FIG. The stop process is a process executed when the engine 10 is stopped. The ECU 50 executes a stop process for stopping the engine 10 when a stop signal is input from the operation unit 41. As shown in FIG. 6, in the stop process, first, the EGR controller 56 controls the EGR valve 27 to a fully closed state (step S31). This makes it difficult for the exhaust gas to remain in the cylinder 12 when the engine 10 is stopped.

  Next, the ECU 50 determines whether or not the throttle valve 30 is in a non-freezing state, that is, whether or not the throttle valve 30 is operable based on the determination result of the most recent freezing determination process (step S32). When the throttle valve 30 is in a frozen state (step S32: NO), that is, when the throttle valve 30 is fixed in an open state, the ECU 50 stops the engine 10 as it is (step S36).

  On the other hand, when the throttle valve 30 is in the non-freezing state (step S32: YES), in the next step S33, the acquisition unit 52 acquires the intake air temperature Ta and the cooling water temperature Tw. The determination unit 53 determines whether or not the freezing condition is satisfied, that is, the intake air temperature Ta is equal to or lower than the first determination value Ta1, and the cooling water temperature Tw is equal to or lower than the second determination value Tw2. Whether or not is established is determined (step S34).

  When the freezing condition is satisfied (step S34: YES), the ECU 50 controls the throttle valve 30 to be fully opened by the throttle control unit 55 (step S35), and stops the engine 10 (step S36). On the other hand, when the freezing condition is not satisfied (step S34: NO), the ECU 50 performs shutter control that is a control to temporarily close the throttle valve 30 by the throttle control unit 55 (step S37), and the engine 10 is Stop (step S36).

  That is, when the throttle valve 30 is operable, but the throttle valve 30 controlled to the fully closed state is likely to freeze in the fully closed state (step S34: YES), the ECU 50 performs shutter control. Without performing this, the engine 10 is stopped in a state where the throttle valve 30 is controlled to be fully opened (step S35). Thereby, when the engine 10 is stopped, the throttle valve 30 is prevented from being stuck in the fully closed state, and the next engine 10 can be started smoothly. On the other hand, when the possibility that the throttle valve 30 is frozen in the fully closed state is low (step S34: NO), the engine 10 is stopped early by suppressing the vibration of the engine 10 by performing shutter control (step S37). be able to.

  By the way, when at least one of the detection value of the intake air temperature sensor 35 and the detection value of the cooling water temperature sensor 36 is abnormal, the reliability regarding the success or failure of the freezing condition is low. For this reason, the reliability of the determination result of the freezing determination process decreases, so that the frequency of erroneous determination regarding freezing of the throttle valve 30 increases. In addition, an inappropriate control mode is likely to be selected in the mode selection process due to an erroneous determination related to freezing, and black smoke and engine output are likely to be reduced. Further, in the stop process, the probability that the throttle valve 30 is frozen in the fully closed state is increased by performing the shutter control of the throttle valve 30 even if the freezing condition is satisfied. Therefore, the ECU 50 detects the presence / absence of abnormality in each of the intake air temperature sensor 35 and the cooling water temperature sensor 36 by the abnormality detection unit 58, and when abnormality is detected in at least one of the intake air temperature sensor 35 and the cooling water temperature sensor 36. The sensor abnormality process is executed.

  For example, the abnormality detection unit 58 detects the intake air temperature when the difference between the intake water temperature Ta detected by the intake air temperature sensor 35 and the coolant temperature Tw detected by the coolant temperature sensor 36 is larger than a threshold value during cold start. It is determined that the sensor 35 or the cooling water temperature sensor 36 is abnormal. Further, for example, the abnormality detection unit 58 calculates an estimated value of the current coolant temperature based on the coolant temperature Tw at the start and the fuel injection amount after the start. And the presence or absence of abnormality in the coolant temperature sensor 36 is determined by comparing the coolant temperature Tw from the coolant temperature sensor 36 with the estimated value. Further, for example, the abnormality detection unit 58 determines whether or not there is an abnormality in the intake air temperature sensor 35 by comparing the outside air temperature detected by the outside air temperature sensor with the intake air temperature Ta of the intake air temperature sensor 35.

  As shown in FIG. 7, in the sensor abnormality process, since abnormality is detected in at least one of the intake air temperature sensor 35 and the cooling water temperature sensor 36, first, the warning control unit 59 controls the warning lamp 42 to be in a lighting state. (Step S41). Next, the ECU 50 stops the execution of the above-described freeze determination processing, mode selection processing, and various types of stop processing (step S42). Then, the throttle control unit 55 controls the throttle valve 30 to a fully open state, and the EGR control unit 56 controls the EGR valve 27 to a fully closed state (step S43), and a series of processing ends. Thereafter, the throttle control unit 55 and the EGR control unit 56 maintain the opening degree of the throttle valve 30 and the EGR valve 27 at the opening degree when the sensor abnormality process ends.

  By executing such sensor abnormality processing, it is possible to suppress a decrease in reliability regarding the success or failure of the freezing condition, and to suppress erroneous determination regarding freezing of the throttle valve 30. Further, by controlling the throttle valve 30 to be fully open and the EGR valve 27 to be fully closed, only the intake air is supplied to the cylinder 12 as the working gas. Thereby, generation | occurrence | production of the black smoke resulting from sensor abnormality and the fall of an engine output can be suppressed. Further, since the throttle valve 30 is not controlled to be fully closed when the engine 10 is stopped, the throttle valve 30 is not stuck in the fully closed state when the engine 10 is stopped due to a sensor abnormality.

According to the embodiment, the effects listed below can be obtained.
(1) When the freezing condition is satisfied when the engine 10 is stopped, the ECU 50 stops the engine 10 while keeping the throttle valve 30 open. Therefore, the throttle valve 30 is prevented from sticking in the fully closed state when the engine 10 is stopped, and the next start of the engine 10 can be performed smoothly. As a result, problems caused by freezing of the throttle valve 30 can be reduced.

  (2) In the freezing determination process, the determination unit 53 determines that the throttle valve 30 is in a frozen state when the sticking detection unit 57 detects sticking of the throttle valve 30 in a state where the freezing condition is satisfied. Thereby, it can be determined whether or not the throttle valve 30 is stuck due to freezing.

  (3) The warning control unit 59 controls the warning lamp 42 to be in a non-lighted state when the throttle valve 30 is stuck due to freezing. Thereby, the erroneous determination about the abnormality of the throttle valve 30 can be suppressed.

  (4) The EGR control unit 56 controls the EGR valve 27 to be fully closed when the throttle valve 30 is frozen. Thereby, generation | occurrence | production of the black smoke accompanying the shortage of intake air and the fall of an engine output can be suppressed.

  (5) The ECU 50 stops the execution of the freezing determination process, the mode selection process, and the stop process when an abnormality is detected in at least one of the intake air temperature sensor 35 and the coolant temperature sensor 36. The throttle control unit 55 controls the throttle valve 30 to a fully open state, and the EGR control unit 56 controls the EGR valve 27 to a fully closed state. Thereby, even when the sensor is abnormally generated, it is possible to suppress erroneous determination regarding freezing of the throttle valve 30, and it is possible to suppress generation of black smoke and a decrease in engine output. Even when the sensor is abnormally generated, it is possible to prevent the throttle valve 30 from freezing in the fully closed state when the engine 10 is stopped.

In addition, the said embodiment can also be suitably changed and implemented as follows.
When the abnormality occurs in at least one of the intake air temperature sensor 35 and the cooling water temperature sensor 36, the throttle control unit 55 detects, for example, an abnormality in each of the sensors 35 and 36 without controlling the throttle valve 30 to the fully open state. The throttle valve 30 may be maintained at the opening when it is set. Even with such a configuration, the throttle valve 30 can be prevented from sticking in the fully closed state when the engine 10 is stopped. If the throttle valve 30 is frozen when an abnormality is detected in the sensors 35 and 36, the throttle valve 30 does not operate even if the throttle valve 30 is fully opened. Therefore, a mechanical load on the throttle valve 30 can be suppressed by maintaining the opening degree of the throttle valve 30.

  The EGR control unit 56 is not limited to the mode in which the EGR valve 27 is controlled to be fully closed when the throttle valve 30 is in a frozen state, for example, the opening degree at which the throttle valve 30 is fixed, the engine speed, and The opening degree of the EGR valve 27 may be controlled according to the fuel injection amount or the like.

  The sticking detection unit 57 includes an instruction change amount that is a change amount of the throttle valve 30 opening due to the trial instruction opening degree tVTcom, and an actual change amount that is a change amount of the detected opening degree VT before and after the output of the trial instruction opening degree tVTcom. May be detected to detect the sticking of the throttle valve 30.

The warning control unit 59 may control the warning lamp 42 to be lit when the throttle valve 30 is in a frozen state.
The warning unit controlled by the warning control unit 59 is not limited to the warning light 42 as long as it warns the driver that an abnormality has occurred in the engine system. For example, a warning sound that generates a warning sound is generated. Part.

  The engine system includes a freeze notification lamp that notifies the driver that the throttle valve 30 is stuck due to freezing, separately from the warning lamp 42, and the ECU 50 lights the freeze notification lamp when the throttle valve 30 is in a frozen state. May be. According to such a configuration, the driver can be notified that the throttle valve 30 is in a frozen state.

  The determination unit 53 may determine that the throttle valve 30 is in a frozen state when the freezing condition is satisfied. According to such a configuration, it is not necessary to determine whether or not the throttle valve 30 is actually fixed. Therefore, it is not necessary to operate the throttle valve 30 in a frozen state in order to determine the presence or absence of sticking, so that a mechanical load on the throttle valve 30 can be suppressed.

  The stop process of the engine 10 is not limited to the case of being started by the input of a stop signal from the operation unit 41, and may be performed when the engine 10 is stopped. For example, in an engine system having an idling stop function, it may be performed when the engine 10 is stopped based on, for example, the remaining battery level, engine speed, vehicle speed, and the like.

  In the stop process, the throttle control unit 55 only needs to keep the throttle valve 30 open when the freezing condition is satisfied. Therefore, the throttle control unit 55 may maintain the throttle valve 30 at an opening just before starting the stop process, instead of being fully opened.

  The first determination value Ta1 and the second determination value Tw2 only need to define a temperature range in which the throttle valve 30 is likely to freeze with respect to the intake air temperature Ta and the cooling water temperature Tw. Therefore, in the freezing condition, the second determination value Tw2 may vary depending on the intake air temperature Ta that is equal to or lower than the first determination value Ta1. That is, the second determination value Tw2 may be set for each intake air temperature Ta that is equal to or lower than the first determination value Ta1. For example, when the first determination value Ta1 is set to 0 ° C., the cooling water temperature Tw = 55 ° C. is set as the second determination value Tw2 with respect to the intake air temperature Ta = −5 ° C. below the first determination value Ta1. The cooling water temperature Tw = 60 ° C. may be set as the second determination value Tw2 with respect to the intake air temperature Ta = −18 ° C. In such a case, the freezing condition includes each intake air temperature Ta equal to or lower than the first determination value Ta1, and a second determination value Tw2 associated with each intake air temperature Ta. When the intake air temperature Ta is equal to or lower than the first determination value Ta1, the determination unit 53 selects the second determination value Tw2 corresponding to the intake air temperature Ta, and the cooling water temperature Tw is the second determination selected. It is determined that the freezing condition is satisfied when the value is equal to or less than the value Tw2. According to such a configuration, the freezing of the throttle valve 30 can be determined with higher accuracy based on the success or failure of the freezing condition. Conversely, the first determination value Ta1 may vary according to each coolant temperature Tw that is equal to or less than the second determination value Tw2. That is, the first determination value Ta1 may be set for each cooling water temperature Tw that is equal to or lower than the second determination value Tw2.

  In the engine system, at least one of stop processing, freezing determination processing, freezing determination processing and mode determination processing, and sensor abnormality processing may be performed. For example, only stop processing may be performed, or only freezing determination processing may be performed. Further, for example, a stop process, a freezing determination process, and a mode determination process may be executed, or a stop process and a sensor abnormality process may be performed. Further, for example, freezing determination processing, mode determination processing, and sensor abnormality processing may be performed.

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 11 ... Cylinder block, 12 ... Cylinder, 13 ... Injector, 14 ... Intake manifold, 15 ... Exhaust manifold, 17 ... Intake passage, 17 ... Turbocharger, 18 ... Compressor, 19 ... Intercooler, 20 ... Exhaust passage , 22 ... Turbine, 25 ... EGR passage, 26 ... EGR cooler, 27 ... EGR valve, 30 ... Throttle valve, 35 ... Intake temperature sensor, 36 ... Coolant temperature sensor, 37 ... Throttle position sensor, 41 ... Operation unit, 42 ... warning light, 50 ... ECU, 51 ... memory, 52 ... acquisition part, 53 ... determination part, 54 ... mode selection part, 55 ... throttle control part, 56 ... EGR control part, 57 ... sticking detection part, 58 ... abnormality detection Part, 59 ... warning control part, 60 ... freezing condition data.

Claims (5)

An acquisition unit that acquires an intake air temperature that is a temperature of intake air and a coolant temperature that is a temperature of engine coolant;
A determination unit for determining success or failure of a freezing condition in which the throttle valve freezes;
A throttle control unit for controlling the opening of the throttle valve,
The freezing condition is satisfied when the intake air temperature is equal to or lower than a first determination value and the cooling water temperature is equal to or lower than a second determination value.
The determination unit determines whether the freezing condition is successful when the engine is stopped,
The control device for a diesel engine, wherein the throttle control unit controls the throttle valve to a fully closed state when the freezing condition is not satisfied, and controls the throttle valve to an open state when the freezing condition is satisfied. An intake air temperature sensor that detects the intake air temperature, and an abnormality detection unit that detects an abnormality in the cooling water temperature sensor that detects the cooling water temperature,
The diesel engine control according to claim 1, wherein the throttle control unit maintains the throttle valve in an open state when the abnormality detection unit detects an abnormality in at least one of the intake air temperature sensor and the cooling water temperature sensor. apparatus. A sticking detector for detecting sticking of the throttle valve;
The acquisition unit acquires a detection opening that is an opening of the throttle valve based on an input signal from a throttle position sensor,
The sticking detection unit detects sticking of the throttle valve by comparing the indicated opening with respect to the throttle valve and the detected opening of the throttle position sensor,
The determination unit determines whether or not the freezing condition is satisfied during operation of the engine, and when the sticking detection unit detects sticking of the throttle valve while the freezing condition is satisfied, the throttle valve is in a frozen state. The diesel engine control device according to claim 1, wherein the control device determines that there is a diesel engine. A warning control unit that controls a warning unit that warns the driver that the throttle valve is stuck;
The diesel engine control device according to claim 3, wherein the warning control unit controls the warning unit to a non-operating state when the throttle valve is in a frozen state. An EGR control unit that controls an EGR valve provided in an EGR passage that connects the exhaust passage and the intake passage of the engine;
The diesel engine control device according to claim 3 or 4, wherein the EGR control unit controls the EGR valve to a fully closed state when the throttle valve is in a frozen state.

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