engine

Abstract

To reduce the possibility of failure such as erroneous operation of an engine by suitably controlling injection of fuel even when a specific sensor is abnormal.SOLUTION: An engine includes: a fuel injection device for injecting fuel into a combustion chamber; an injection control unit for controlling injection of fuel by the fuel injection device on the basis of an injection parameter; and a sensor for outputting a value in accordance with an operation state of the engine. When a specific sensor included in the sensor is abnormal, the injection control unit uses a prescribed value set in advance instead of an output value of the specific sensor and corrects the injection parameter on the basis of the prescribed value.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an engine. [Background technology]

[0002] 2. Description of the Related Art Conventionally, engines have been proposed in which the amount of fuel injection is controlled based on the output value of a sensor (for example, a water temperature sensor) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-136546 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when a particular sensor (e.g., a water temperature sensor) that has a large effect on fuel injection control is abnormal, the output value of that sensor will be an incorrect value compared to the output value when the sensor is normal. When the incorrect output value of the particular sensor is sent to the control unit, the control unit controls fuel injection based on the incorrect output value, which may cause problems such as engine malfunction. In this regard, Patent Document 1 does not consider at all the control of fuel injection when a particular sensor is abnormal.

[0005] The present invention has been made to solve the above-mentioned problems, and its object is to provide an engine that can appropriately control fuel injection even when a specific sensor is abnormal, thereby reducing the risk of malfunctions such as engine failure. [Means for solving the problem]

[0006] An engine according to one aspect of the present invention is an engine equipped with a fuel injection device that injects fuel into a combustion chamber, and is equipped with an injection control unit that controls the injection of fuel by the fuel injection device based on injection parameters, and a sensor that outputs a value corresponding to the operating state of the engine, and when a specific sensor included in the sensors is abnormal, the injection control unit uses a predetermined value that has been set in advance instead of the output value of the specific sensor, and corrects the injection parameter based on the predetermined value. Effect of the Invention

[0007] According to the above configuration, even if a specific sensor is abnormal, the fuel injection can be appropriately controlled, thereby reducing the risk of problems such as engine malfunction. [Brief description of the drawings]

[0008] [Figure 1] 4 is a graph showing an example of a torque curve in each operation mode of the engine. [Diagram 2] 1 is an explanatory diagram that illustrates a schematic configuration of an engine according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a block diagram showing a configuration of a main part of the engine. [Figure 4] FIG. 2 is an explanatory diagram illustrating a concept of fuel injection control in the embodiment. [Diagram 5] 5 is a flowchart showing a process flow of the injection control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

[0010] [1. Supplementary information regarding the assignment] First, a supplementary explanation will be given on the problems of the conventional technology described above. In recent years, regulations on engine exhaust gas have been increasingly strengthened in various countries. In order to comply with the regulations, control is performed to perform each diagnosis of NCD (Nox Control Diagnosis) or PCD (Particulate Control Diagnosis). Note that NCD refers to a diagnosis related to an EGR device described later, and PCD refers to a diagnosis related to a DPF (Diesel Particulate Filter) described later.

[0011] For example, when an abnormality occurs in a specific sensor and an error occurs in the diagnosis of the NCD, the operation mode is controlled to gradually reduce the engine power (torque, rotation speed). FIG. 1 shows an example of a torque curve in each operation mode. When an error is detected in the NCD, the operation mode is shifted from the normal mode to the first mode (Low-level) after a predetermined time has elapsed since the error detection, and then the operation mode is shifted from the first mode to the second mode (Severe) after a further predetermined time has elapsed. When the maximum torque of the engine exceeds a value specified for each mode after the operation mode is shifted to the first mode or the second mode, the above regulation cannot be adequately satisfied.

[0012] Therefore, in this embodiment, when a specific sensor is abnormal, the fuel injection control described below is performed to prevent the engine output from exceeding a specified value, that is, to reduce engine malfunction.

[0013] [2. Engine configuration] The configuration of the engine of this embodiment will be described below. Fig. 2 is an explanatory diagram that shows a schematic configuration of the engine 1 of this embodiment. Fig. 3 is a block diagram that shows the configuration of the main parts of the engine 1. The engine 1 is, for example, a diesel engine, and is mounted on a work vehicle (work machine), an agricultural machine, a ship, etc.

[0014] The engine 1 includes, as components of its intake system, an intake pipe 4 and an intake manifold 5. The intake pipe 4 draws in gas from the outside and supplies it to the intake manifold 5.

[0015] The intake manifold 5 divides the gas supplied from the intake pipe 4 into a number of portions corresponding to the number of cylinders (for example, four in FIG. 2), and supplies the divided portions to a cylinder head 6. The cylinder head 6 has a cylinder head cover (not shown) that covers each cylinder, and an injector 7 (fuel injection device) provided corresponding to the combustion chamber 6a of each cylinder. The injector 7 is controlled by an ECU (engine control unit) 9, and injects fuel stored at high pressure in a common rail 8 into the combustion chamber 6a of each cylinder at a predetermined timing. That is, the engine 1 is provided with the injector 7 as a fuel injection device that injects fuel into the combustion chamber 6a. Each cylinder is provided with a piston that slides back and forth within the combustion chamber 6a and rotates the crankshaft via a connecting rod.

[0016] An intake temperature sensor 11 is attached to the intake manifold 5. The intake temperature sensor 11 detects the temperature of the gas in the intake manifold 5 and outputs the temperature to the ECU 9.

[0017] The engine 1 includes an exhaust manifold 12, an exhaust pipe 13, and an exhaust gas purification device 14 as components of its exhaust system.

[0018] The exhaust manifold 12 collects gas (exhaust gas) generated in the multiple combustion chambers 6a. A portion of the gas that passes through the exhaust manifold 12 is supplied to an EGR device 18 via an EGR (Exhaust Gas Recirculation) pipe 17, and the remaining gas is supplied to an exhaust gas purification device 14 via an exhaust pipe 13.

[0019] The EGR device 18 is an exhaust gas recirculation device that returns a portion of the exhaust gas discharged from the cylinder head 6 to the intake pipe 4, and includes an EGR cooler 19 and an EGR valve 20. The EGR cooler 19 cools the exhaust gas. The EGR device 18 changes the amount of exhaust gas supplied to the intake manifold 5 by adjusting the opening of the EGR valve 20. By mixing the exhaust gas with the gas taken into the intake manifold 5, the amount of oxygen in the taken gas is reduced, and the combustion temperature can be lowered. This makes it possible to reduce the generation of nitrogen oxides called NOx and comply with exhaust gas regulations (emission regulations). The opening of the EGR valve 20 is detected by an EGR valve opening sensor (not shown).

[0020] If an abnormality occurs with the EGR device 18, the ECU 9 determines that an error has occurred in the above-mentioned NCD diagnosis, transitions the operating mode of the engine 1 to the above-mentioned first mode or second mode, and performs fuel injection control to gradually transition (reduce) the power (torque, rotation speed) of the engine 1.

[0021] The exhaust gas purification device 14 is a device that purifies and discharges exhaust gas, and is also called DPF. The exhaust gas purification device 14 includes an oxidation catalyst 21 and a filter 22. The oxidation catalyst 21 is a catalyst for oxidizing (burning) unburned fuel, carbon monoxide, nitrogen monoxide, and the like contained in the exhaust gas, and is made of platinum or the like. The filter 22 is configured as, for example, a wall-flow type filter, and collects PM (Particulate Matter) contained in the exhaust gas treated by the oxidation catalyst 21.

[0022] As shown in Fig. 3, the engine 1 further includes a water temperature sensor 31 and an engine revolution speed sensor 32. The water temperature sensor 31 detects the temperature of engine cooling water passing through a water jacket (not shown) provided in the cylinder head 6. The engine cooling water circulates and flows through a cooling water passage between the water jacket and the radiator by driving a water pump. The low-temperature engine cooling water cooled by the radiator passes through the water jacket, thereby cooling the engine main body 1a including the cylinder head 6.

[0023] The engine speed sensor 32 detects the rotation speed of the crankshaft of the engine 1 as the rotation speed of the engine 1. Information on the rotation speed detected by the engine speed sensor 32 is output to the ECU 9.

[0024] Each of the above-mentioned sensors (intake air temperature sensor 11, water temperature sensor 31, engine speed sensor 32, etc.) detects its respective detection target and outputs a value corresponding to the operating state of engine 1 to ECU 9. That is, engine 1 of this embodiment includes a sensor that outputs a value corresponding to the operating state of engine 1. In particular, engine 1 of this embodiment includes a plurality of sensors.

[0025] In addition, the engine 1 may further include other sensors, such as an atmospheric pressure sensor that detects atmospheric pressure. By including the atmospheric pressure sensor, the ECU 9 can recognize the altitude of the environment in which the engine 1 is used based on the detected atmospheric pressure, and control the operating conditions of the engine 1 according to the recognized altitude.

[0026] The ECU 9 described above is a controller that controls the operation of each part of the engine 1. In particular, in this embodiment, the ECU 9 functions as an injection control part that controls the injection of fuel by the injector 7 based on injection parameters. The injection parameters include at least one of the fuel injection amount, injection timing, and injection pressure. The ECU 9 also functions as a timer that measures time. Furthermore, the ECU 9 also has a storage part that stores an injection map, which will be described later, a control program for the ECU 9, and the like.

[0027] Incidentally, when the engine 1 is in a low temperature state and the engine coolant is low in temperature, it is difficult to start the engine 1, so it is necessary to fine-tune the injection timing when the injector 7 injects fuel in multiple stages. Therefore, it can be said that the temperature of the engine coolant has a large effect on the fuel injection control.

[0028] Therefore, in this embodiment, the water temperature sensor 31, which has a large effect on the fuel injection control, is considered as a specific sensor, and the way in which the ECU 9 corrects the fuel injection timing, etc. is changed depending on whether or not an abnormality has occurred in the water temperature sensor 31. The fuel injection control will be described in more detail below.

[0029] [3. Fuel injection control flow] Fig. 4 is an explanatory diagram that shows a schematic concept of the fuel injection control of this embodiment. Fig. 5 is a flowchart showing the flow of processing by the fuel injection control of this embodiment. As an example, consider fuel injection control when work is performed by a work vehicle (e.g., a hydraulic excavator) equipped with the engine 1 of this embodiment.

[0030] First, the ECU 9 judges whether or not an abnormality has occurred in the water temperature sensor 31 (S1). For example, when a predetermined time has passed since the engine 1 started, the engine 1 warms up and the temperature of the engine coolant rises. Therefore, if the output value (temperature) of the water temperature sensor 31 is equal to or higher than a threshold value after the predetermined time has passed since the engine 1 started, the ECU 9 can judge that the water temperature sensor 31 is normal, and if the output value (temperature) is less than the threshold value, the ECU 9 can judge that the water temperature sensor 31 is abnormal. If the water temperature sensor 31 is abnormal, the ECU 9 cannot diagnose the NCD and therefore simultaneously recognizes an NCD error. If the water temperature sensor 31 is abnormal, the start of PCD diagnosis is not permitted either.

[0031] If the ECU 9 determines in S1 that the water temperature sensor 31 is normal (No in S1), it determines the injection parameters based on the engine speed detected by the engine speed sensor 32, the command injection amount, and a previously prepared injection map (S2).

[0032] Here, the command injection amount refers to the amount of fuel to be injected from the injector 7 (if injection is performed in multiple stages during one cycle, the total amount of injection at each stage) that is determined by the ECU 9 according to the opening of the accelerator pedal depressed by the operator operating the work vehicle. The maximum value of the command injection amount is a value that can realize the maximum torque (100%) that the engine 1 can output. The opening of the accelerator pedal is detected by an accelerator opening sensor (not shown) on the work vehicle side and input to the ECU 9.

[0033] Next, the ECU 9 corrects the injection parameters determined in S2 based on the output value (temperature of the engine coolant) of the normal water temperature sensor 31 (S3). For example, when the output value of the water temperature sensor 31 is a relatively low temperature, the ECU 9 calculates a correction value (for example, several degrees in advance) for advancing the fuel injection timing by an amount corresponding to the output value in order to facilitate ignition in the combustion chamber 6a, and performs a correction by adding the correction value to the injection timing determined in S2. This correction is also called "environmental correction", and the correction value is also called "environmental correction amount".

[0034] Next, the ECU 9 injects fuel from the injector 7 in multiple stages using the injection parameters corrected in S3 (S4). This provides the relationship between engine speed and torque, for example, the torque curve in normal mode shown in Fig. 1. Thereafter, in S5, if the ignition key of the work vehicle is turned OFF, fuel injection is stopped and the series of processes is terminated, and if the ignition key is not OFF, the process returns to S1 and the processes from S1 onwards are continued.

[0035] Even if the ECU 9 determines in S1 that the water temperature sensor 31 is abnormal (Yes in S1), if a first predetermined time (e.g., 36 hours) has not elapsed since the occurrence of the abnormality (Yes in S6), the ECU 9 does not transition the operating mode to the first mode in order to avoid the inconvenience of work due to transitioning to the first mode (powering down the engine 1), and executes the processing from S2 onwards described above.

[0036] On the other hand, if the first predetermined time has elapsed since the occurrence of the abnormality in the water temperature sensor 31 (No in S6) and the second predetermined time (e.g., 100 hours) has not elapsed (Yes in S7), the ECU 9 proceeds to S8 and performs the fuel injection control in the first mode.

[0037] In S8, the ECU 9 determines the injection parameters based on the engine speed and the command injection amount in the same manner as in S2. Here, the maximum torque (for example, 75% of normal torque) is defined by the injection map for the first mode (maximum injection amount map). The maximum injection amount map is configured by the engine speed and the output value of the water temperature sensor 31.

[0038] Next, the ECU 9 uses a preset value (default value) instead of the output value of the water temperature sensor 31, and corrects the injection parameters determined in S8 based on the preset value (S9). The preset value is a representative value that represents the value output from the water temperature sensor 31 when the water temperature sensor 31 is normal. For example, in S9, each injection timing in multi-stage fuel injection is corrected based on the preset value.

[0039] Next, the ECU 9 injects fuel from the injector 7 in multiple stages using the injection parameters corrected in S9 (S4). As a result, a torque curve in the first mode, for example, as shown in FIG. 1, is obtained as the relationship between engine speed and torque. Note that the torque in the torque curve indicates the maximum torque value that can be obtained in the first mode. Thereafter, in S5, if the ignition key of the work vehicle is turned OFF, fuel injection is stopped and the series of processes is terminated, and if the ignition key is not OFF, the process returns to S1 and the processes from S1 onwards are continued.

[0040] In addition, in the above-mentioned S7, when the ECU 9 determines that the second predetermined time has elapsed since the occurrence of the abnormality in the water temperature sensor 31 (No in S7), the ECU 9 proceeds to S10 and performs the fuel injection control in the second mode.

[0041] In S10, the ECU 9 determines the injection parameters based on the engine speed and the command injection amount in the same manner as in S2. Here, the maximum torque (for example, 50% of normal torque) is defined by the injection map for the second mode (maximum injection amount map). The maximum injection amount map is configured by the engine speed and the output value of the water temperature sensor 31.

[0042] Then, the process proceeds to S9, where the ECU 9 uses a preset value instead of the output value of the water temperature sensor 31, and corrects the injection parameters (e.g., injection timing) determined in S10 based on the preset value. The ECU 9 then injects fuel from the injector 7 in multiple stages using the injection parameters corrected in S9 (S4). As a result, a torque curve in the second mode, for example, as shown in FIG. 1, is obtained as a relationship between engine speed and torque. Note that the torque in the torque curve indicates the maximum torque value that can be obtained in the second mode. Then, in S5, if the ignition key of the work vehicle is turned OFF, the process stops fuel injection and ends the series of processes. If the ignition key is not OFF, the process returns to S1, and the processes from S1 onwards are continued.

[0043] After S5, by returning to S1 as necessary, if the water temperature sensor 31 returns to a normal state after performing processes in the order of S1, S6, S7, S10, S9, S4, and S5 due to an abnormal state of the water temperature sensor 31, the processes can be performed in the order of S1, S2, S3, S4, and S5. In other words, when the water temperature sensor 31 returns to a normal state from an abnormal state, the correction of the injection parameters returns from the correction based on the predetermined value (S9) to the correction based on the output value of the normal water temperature sensor 31 (S3).

[0044] 4, in this embodiment, if the water temperature sensor 31 is normal, the output value of the water temperature sensor 31 is supplied to other control modules of the work vehicle that are not related to the control of the engine 1, and if the water temperature sensor 31 is abnormal, a predetermined value (default value) is supplied. In this case, the risk of malfunction due to an abnormality in the water temperature sensor 31 can be reduced in the control module on the work vehicle side.

[0045] Furthermore, regardless of whether the water temperature sensor 31 is abnormal or normal, the output value of the water temperature sensor 31 is constantly monitored by the ECU 9. This allows the ECU 9 to monitor, based on the output value, whether the water temperature sensor 31 has recovered from an abnormal state.

[0046] As described above, when a specific sensor included in the sensors (e.g., water temperature sensor 31) is abnormal, the ECU 9 as the injection control unit uses a predetermined value set in advance instead of the output value of the specific sensor, and corrects the injection parameters based on the predetermined value (S9).

[0047] If a specific sensor is abnormal, and the ECU 9 corrects the injection parameters based on the output value of that specific sensor and controls fuel injection based on the corrected injection parameters, the correction of the injection parameters based on an erroneous output value and the erroneous injection control based on the above injection parameters may be performed, which may cause problems such as malfunction of the engine 1.

[0048] In this embodiment, when a specific sensor is abnormal, the injection parameters are appropriately corrected based on the above-mentioned predetermined value instead of the erroneous output value, so that the fuel injection can be appropriately controlled based on the corrected injection parameters. This makes it possible to reduce the risk of problems such as malfunction of the engine 1 even when a specific sensor is abnormal. For example, even when the operation mode transitions to the first mode or the second mode because a specific sensor is abnormal, it is possible to suppress the maximum torque of the engine 1 to a specified value or less (75% or less or 50% or less of the normal maximum torque) by appropriately correcting the injection parameters and controlling the fuel injection based on the corrected injection parameters.

[0049] In this embodiment, even if a sensor other than the water temperature sensor 31, such as the intake air temperature sensor 11, among the multiple sensors is abnormal, the ECU 9 corrects the injection parameters based on the presence or absence of an abnormality in the water temperature sensor 31 (S3, S9). That is, when a sensor other than a specific sensor is abnormal, the ECU 9 corrects the injection parameters based on the presence or absence of an abnormality in the specific sensor. In this case, the correction of the injection parameters and the fuel injection control can be performed by placing importance on the presence or absence of an abnormality in the specific sensor among the multiple sensors.

[0050] In this embodiment, when the specific sensor is normal, the ECU 9 corrects the injection parameters based on the output value of the specific sensor (S3). When the specific sensor is normal, the ECU 9 corrects the normal injection parameters based on the output value of the specific sensor to control the fuel injection, thereby allowing the engine 1 to operate with a normal torque curve (without limiting the torque).

[0051] In this embodiment, the ECU 9 constantly monitors the output value of a specific sensor, and when the specific sensor returns to normal from an abnormal state, it reverts the correction of the injection parameters from correction based on a predetermined value to correction based on the output value of the specific sensor (S9, S5, S1, S3).

[0052] The ECU 9 can constantly monitor whether the specific sensor has returned to a normal state from an abnormal state based on the output value by constantly monitoring the output value of the specific sensor. When the specific sensor has returned to a normal state from an abnormal state, the ECU 9 can restore normal fuel injection control based on the output value by changing the correction of the injection parameters from the correction based on the predetermined value to the correction based on the output value of the specific sensor.

[0053] Furthermore, when an output value of the specific sensor is less than a threshold value after a predetermined time has elapsed since the start of the engine 1, the ECU 9 determines that the specific sensor is abnormal (S1). This allows the ECU 9 to accurately determine whether the specific sensor is abnormal.

[0054] Moreover, the above-mentioned specific sensor is the water temperature sensor 31 that detects the temperature of engine cooling water. As described above, the water temperature sensor 31 has a greater effect on fuel injection control than other sensors, so when the specific sensor is the water temperature sensor 31, the control of this embodiment that corrects the injection parameters based on the output value or a predetermined value of the specific sensor to reduce malfunction of the engine 1 is very effective.

[0055] Moreover, the above-mentioned predetermined value is a representative value of the output value when the specific sensor (water temperature sensor 31) is normal. As a result, even if the specific sensor is abnormal, the injection parameters can be correctly corrected based on the above-mentioned predetermined value, and the fuel injection can be correctly controlled based on the corrected injection parameters. As a result, even if the specific sensor is abnormal, the risk of malfunction of the engine 1 or other problems occurring can be reliably reduced.

[0056] The injection parameters include at least one of the fuel injection amount, injection timing, and injection pressure. The ECU 9 corrects at least one of these parameters, and injects fuel from the injector 7 with an appropriate injection amount, injection timing, or injection pressure based on the corrected injection parameters, thereby preventing the engine 1 from malfunctioning or other problems.

[0057] Although the engine 1 of this embodiment does not include a turbocharger, the fuel injection control described in this embodiment can be applied even if the engine 1 includes a turbocharger.

[0058] Although the embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and the invention can be expanded or modified without departing from the spirit of the invention. [Industrial Applicability]

[0059] The engine of the present invention can be used in, for example, work vehicles, agricultural machines, and the like. [Explanation of symbols]

[0060] 1 Engine 6a Combustion chamber 7 Injector (fuel injection device) 9 ECU (injection control unit) 11 Intake Air Temperature Sensor 31 Water temperature sensor (specific sensor) 32 Engine speed sensor

Claims

1. An engine equipped with a fuel injection device that injects fuel into a combustion chamber, an injection control unit that controls the injection of the fuel by the fuel injection device based on an injection parameter; a sensor that outputs a value corresponding to an operating state of the engine; the injection control unit, when a specific sensor included in the sensors is abnormal, reduces an output of the engine, uses a predetermined value set in advance instead of the output value of the specific sensor, and corrects the injection parameters based on the predetermined value; the injection control unit, when the specific sensor is abnormal, corrects the injection parameters based on the output value of the specific sensor until a predetermined time has elapsed since the occurrence of the abnormality; the injection control unit performs fuel injection control to gradually reduce power of the engine by shifting an operation mode of the engine from a normal mode to a first mode and a second mode in that order according to an elapsed time from the occurrence of the abnormality; In the first mode, the injection parameter determined from the injection map for the first mode is corrected based on the predetermined value; In the second mode, the injection parameter determined from the injection map for the second mode is corrected based on the predetermined value.

2. The engine according to claim 1 , wherein the injection control unit reduces an output of the engine in a stepwise manner when the specific sensor is abnormal.

3. An engine as described in claim 1 or 2, wherein the injection control unit corrects the injection parameters based on the output value of the specific sensor when the specific sensor is normal.

4. An engine described in any of claims 1 to 3, wherein the injection control unit constantly monitors the output value of the specific sensor, and when the specific sensor returns to normal from an abnormality, reverts the correction of the injection parameters from correction based on the predetermined value to correction based on the output value of the specific sensor.

5. An engine described in any of claims 1 to 4, wherein the injection control unit determines that the particular sensor is abnormal if the output value of the particular sensor is less than a threshold value after a predetermined time has elapsed since the engine begins to start.

6. An engine as described in any of claims 1 to 5, wherein the specific sensor is a water temperature sensor that detects the temperature of the engine's cooling water.

7. An engine described in any one of claims 1 to 6, wherein the specified value is a representative value representing the value output when the specific sensor is normal.

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