engine

Abstract

To accurately determine an abnormality of an intake pressure sensor.SOLUTION: An engine comprises a cylinder head, an intake manifold that supplies gas to the cylinder head, an intake pressure sensor that measures an intake pressure inside the intake manifold, a fuel injection device that injects fuel into a combustion chamber inside the cylinder head, and a control unit that determines the abnormality of the intake pressure sensor. The control unit determines an abnormality in the intake pressure sensor based on a determination parameter and a determination threshold value defined according to a measured value of the intake pressure measured by the intake pressure sensor after a fuel injection amount by a fuel injection device exceeds a predetermined amount.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an engine.

Background Art

[0002] Conventionally, a technique has been proposed in which an intake pressure sensor is arranged in an intake manifold and the intake pressure measured by the intake pressure sensor is used for engine control (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, engine exhaust gas regulations (emission regulations) have been strengthened. Along with this, it has been required to determine whether various sensors provided in the engine are operating normally (sensor validity diagnosis). For example, if the intake pressure sensor fails, is removed, or the output of the intake pressure sensor is fixed by using a dummy resistor, it becomes difficult to appropriately control the engine, and it becomes difficult to reduce the amount of harmful substances contained in the exhaust gas. Therefore, it is necessary to accurately determine an abnormality of the intake pressure sensor, including a failure of the intake pressure sensor.

[0005] In this regard, in the above-described Patent Document 1, no method for accurately determining an abnormality of the intake pressure sensor has been considered at all in order to cope with emission regulations.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide an engine capable of accurately determining an abnormality of an intake pressure sensor.

Means for Solving the Problems

[0007] An engine according to one aspect of the present invention comprises a cylinder head, an intake manifold for supplying gas to the cylinder head, an intake pressure sensor for measuring the intake pressure in the intake manifold, and a fuel injection device for injecting fuel into the combustion chamber in the cylinder head, further comprising a control unit for determining an abnormality in the intake pressure sensor, wherein the control unit, after the amount of fuel injected by the fuel injection device exceeds a predetermined amount, measures the actual value of the intake pressure measured by the intake pressure sensor. If the absolute value of the difference with atmospheric pressure is greater than the absolute value of the judgment threshold, the intake pressure sensor is determined to be normal. Conversely, if the absolute value of the difference is less than or equal to the absolute value of the judgment threshold, the intake pressure sensor is determined to be abnormal. [Effects of the Invention]

[0008] With the above configuration, abnormalities in the intake pressure sensor can be detected with high accuracy. [Brief explanation of the drawing]

[0009] [Figure 1] This is a plan view showing the schematic configuration of an engine according to one embodiment of the present invention. [Figure 2] This is a schematic diagram illustrating the internal structure of the main components of the engine described above. [Figure 3] This graph schematically shows the changes in engine speed, fuel injection amount, and intake pressure over time. [Figure 4] This is a schematic diagram illustrating the relationship between engine speed, torque, and intake pressure in a naturally aspirated (NA) engine. [Figure 5] This is a schematic block diagram showing the main components of a diesel engine system, including an engine with generator specifications. [Figure 6] This graph shows the relationship between the instructed fuel injection amount and the judgment parameter in a generator-type engine. [Modes for carrying out the invention]

[0010] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

[0011] [1. Engine Configuration] Figure 1 is a plan view showing the schematic configuration of engine 1 in this embodiment, and Figure 2 is an explanatory diagram schematically showing the internal configuration of the main part of engine 1. Engine 1 is, for example, a diesel engine and is installed in work machines, ships, etc.

[0012] Engine 1 comprises an intake pipe 2, a supercharger 3, an intake pipe 4, and an intake manifold 5 as components of the intake system. The intake pipe 2 draws in gas from the outside. The intake pipe 2 is equipped with a filter (not shown) to remove dust and other particles from the gas.

[0013] The supercharger 3 comprises a turbine 3a and a compressor 3b. The turbine 3a is configured to rotate using the exhaust gas flowing into the exhaust pipe 13. The compressor 3b is located between the intake pipe 2 and the intake pipe 4 and is connected to a shaft 3c which is connected to the turbine 3a, and rotates in conjunction with the rotation of the turbine 3a. The supercharger 3 compresses air and forcibly draws it in by the rotation of the compressor 3b. The intake pipe 4 supplies the gas drawn in by the supercharger 3 to the intake manifold 5.

[0014] 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 Figures 1 and 2) and supplies them to the cylinder head 6. The cylinder head 6 has a cylinder head cover 7 that covers each cylinder and an injector 8 (fuel injection device) provided corresponding to each cylinder. The injector 8 is controlled by an ECU (engine control unit) 9 and injects fuel into the combustion chamber of each cylinder at a predetermined timing. Each cylinder is provided with a piston that reciprocates within the combustion chamber and rotates the crankshaft via a connecting rod.

[0015] An intake pressure sensor 10 is attached to the intake manifold 5. The intake pressure sensor 10 detects the pressure of the gas inside the intake manifold 5 (intake pressure) and outputs it to the ECU 9.

[0016] That is, the engine 1 of the present embodiment includes a cylinder head 6, an intake manifold 5 that supplies gas to the cylinder head 6, an intake pressure sensor 10 that measures the intake pressure in the intake manifold 5, and an injector 8 as a fuel injection device that injects fuel into the combustion chamber in the cylinder head 6.

[0017] As members of the exhaust system, the engine 1 includes an exhaust manifold 12, an exhaust pipe 13, and an exhaust gas purification device 14.

[0018] The exhaust manifold 12 collects the exhaust gas generated in the plurality of combustion chambers and supplies it to the turbine 3a of the supercharger 3. An exhaust temperature sensor 16 is attached to the manifold 12. The exhaust temperature sensor 16 detects the temperature of the gas in the exhaust manifold 12 and outputs the information to the ECU 9.

[0019] Part of the gas that has passed through the exhaust manifold 12 is supplied to the EGR (Exhaust Gas Recirculation) device 18 via the EGR pipe 17, and the remaining gas is supplied to the exhaust gas purification device 14 via the exhaust pipe 13.

[0020] The EGR device 18 is an exhaust gas recirculation device that returns a part 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 degree of the EGR valve 20. By mixing exhaust gas into the gas sucked into the intake manifold 5, the amount of oxygen in the sucked gas decreases, so the combustion temperature can be lowered. Thereby, the generation of nitrogen oxides called NOx can be reduced, and the exhaust gas regulation (emission regulation) can be complied with.

[0021] In other words, the engine 1 of this embodiment further includes an EGR device 18, which is an exhaust gas recirculation device that returns a portion of the exhaust gas discharged from the cylinder head 6 back to the intake pipe 4 connected to the intake manifold 5. The EGR device 18 has an EGR valve 20, which is an exhaust gas adjustment valve that adjusts the amount of exhaust gas supplied to the intake pipe 4.

[0022] The exhaust gas purification device 14 purifies and discharges exhaust gas. The exhaust gas purification device 14 comprises an oxidation catalyst 21 and a filter 22. The oxidation catalyst 21 is a catalyst for oxidizing (combusting) unburned fuel, carbon monoxide, nitric oxide, etc. contained in the exhaust gas, and is made of platinum or the like. The filter 22 is configured, for example, as a wall-flow type filter and collects PM (particulate matter) contained in the exhaust gas treated by the oxidation catalyst 21.

[0023] The ECU9 described above functions as a control unit that determines whether the intake pressure sensor 10 is functioning normally, that is, whether there is an abnormality in the intake pressure sensor 10. In other words, the engine 1 of this embodiment is equipped with an ECU9 as a control unit that determines abnormalities in the intake pressure sensor 10. Here, abnormalities in the intake pressure sensor 10 include not only failure of the intake pressure sensor 10, but also tampering with (tampering with) and removal of the intake pressure sensor 10, and fixing the output of the intake pressure sensor 10 by using a dummy resistor. The details of how the ECU9 determines abnormalities in the intake pressure sensor 10 will be described below.

[0024] [2. Method for detecting abnormalities in the intake pressure sensor] Figure 3 is a schematic graph showing the fluctuations of engine speed, fuel injection amount, and intake pressure over time. At time t0, when the ignition key is inserted into the key cylinder and turned to the ON position, the intake pressure sensor 10 measures the current intake pressure as the measured value p1 (kPa). At time t1, the ECU 9 adjusts the output (zero point) of the intake pressure sensor 10 so that the measured value p1 of the intake pressure matches the atmospheric pressure p0 (kPa) measured by the atmospheric pressure sensor (not shown). That is, at time t1, engine 1 has not yet started, so p1 = p0. Atmospheric pressure p0 is the reference value of the intake pressure before engine 1 starts, and changes in intake pressure after time t1 are changes in intake pressure relative to atmospheric pressure. Hereafter, the difference between the measured value p1 of the intake pressure measured by the intake pressure sensor 10 and the above reference value (atmospheric pressure p0) will be referred to as the judgment parameter PA (kPa). The atmospheric pressure p0 may be pre-set by default depending on the operating environment of engine 1 (e.g., altitude).

[0025] At time t2, turning the ignition key further to the start position causes the starter motor to rotate and engine 1 to start. At this time, the rotational speed of engine 1 is approximately 800 to 1200 revolutions per minute (800 to 1200 min). -1 This is a low rotational speed, and this state is called the L / I (Low idling) state. When engine 1 starts, the amount of fuel injected by injector 8 increases. Also, because air is forcibly drawn in by supercharger 3, the measured value p1 of the intake pressure measured by intake pressure sensor 10 increases to the positive side. For this reason, the judgment parameter PA mentioned above increases to the positive side.

[0026] If, at time t3, the amount of fuel injected by injector 8 exceeds a predetermined amount V1, ECU 9 will perform the following determination at time t4 or later, after a predetermined time T (for example, 5 seconds) has elapsed from time t3. Since ECU 9 constantly monitors and controls the amount of fuel injected, it can easily determine whether or not the amount of fuel injected has exceeded the predetermined amount V1.

[0027] The ECU 9 compares the determination parameter PA with the determination threshold value Pth. When the determination parameter PA is greater than the determination threshold value Pth, the ECU 9 determines that the intake air pressure sensor 10 is normal. On the other hand, when the determination parameter PA is less than or equal to the determination threshold value Pth, the ECU 9 determines that the intake air pressure sensor 10 is abnormal.

[0028] For example, assume that the reference value (= atmospheric pressure) is 100 kPa, the actually measured value of the intake air pressure is 110 kPa, and the determination threshold value Pth is 2 kPa. In this case, PA = 110 - 100 = 10 kPa, and PA > Pth. Therefore, in this case, the ECU 9 determines that the intake air pressure sensor 10 is normal. On the other hand, for example, when the actually measured value of the intake air pressure is 101 kPa, PA = 101 - 100 = 1 kPa, and PA < Pth. In this case, the ECU 9 determines that the intake air pressure sensor 10 is not functioning properly and is abnormal.

[0029] When the ECU 9 determines that the intake air pressure sensor 10 is abnormal, it gives an alarm to the surroundings and prompts the surroundings to inspect and confirm the intake air pressure sensor 10. The above alarm can be performed, for example, by lighting a lamp (not shown) or sounding a buzzer (not shown).

[0030] As described above, the ECU 9 as the control unit determines the abnormality of the intake air pressure sensor 10 based on the determination parameter PA defined according to the actually measured value of the intake air pressure measured by the intake air pressure sensor 10 and the determination threshold value Pth after the fuel injection amount by the injector 8 exceeds a predetermined amount V1 (after time t3).

[0031] As "after the fuel injection amount exceeds the predetermined amount V1", for example, it is possible to consider the situation after the engine 1 starts and transitions to the normal operation state. Since the determination parameter PA is a parameter defined according to the actually measured value p1 of the intake air pressure, by determining the abnormality of the intake air pressure sensor 10 based on the determination parameter PA and the determination threshold value Pth after the fuel injection amount exceeds the predetermined amount V1, the abnormality of the intake air pressure sensor 10 can be accurately determined using the value of the intake air pressure actually measured in the normal operation state of the engine 1.

[0032] In particular, the judgment parameter PA is the difference between the measured intake pressure p1 and the reference intake pressure value (e.g., atmospheric pressure p0) set before starting the engine 1. By using the difference between the measured intake pressure p1 and the reference intake pressure value before starting the engine 1 as the judgment parameter PA, the ECU 9 can accurately determine abnormalities in the intake pressure sensor 10 by comparing the judgment parameter PA with the judgment threshold Pth, even when the operating environment of the engine 1 is different (for example, when atmospheric pressure fluctuates due to different altitudes).

[0033] Furthermore, the ECU 9 determines that the intake pressure sensor 10 is normal when the determination parameter PA is greater than the determination threshold Pth, and determines that the intake pressure sensor 10 is abnormal when the determination parameter PA is less than or equal to the determination threshold Pth. In a configuration where the engine 1 is equipped with a supercharger 3, the abnormality of the intake pressure sensor 10 can be accurately determined based on the relationship between the determination parameter PA and the determination threshold Pth as described above.

[0034] In this embodiment, the reference value for intake pressure is the atmospheric pressure p0 in the operating environment of the engine 1. Atmospheric pressure p0 fluctuates depending on the operating environment of the engine 1 (especially altitude). By using atmospheric pressure p0 as the reference value, the above-mentioned effect of accurately determining abnormalities in the intake pressure sensor 10 can be reliably obtained for each different operating environment of the engine 1.

[0035] Furthermore, the ECU9 determines that there is an abnormality in the intake pressure sensor 10 after a predetermined time T has elapsed from the point when the fuel injection amount exceeds a predetermined amount V1 (time t3).

[0036] During the transition period from when engine 1 is started to when it transitions to normal operation, the intake pressure does not immediately rise in line with the increase in engine speed, resulting in unstable intake pressure behavior. Therefore, if an abnormality in the intake pressure sensor 10 is detected using the judgment parameter PA during this transition period, false detections are likely to occur. By detecting the abnormality in the intake pressure sensor 10 after a predetermined time T has elapsed from the point when the fuel injection amount exceeds a predetermined amount V1 (for example, at time t4), it is possible to detect the abnormality in the intake pressure sensor 10 when engine 1 has transitioned to normal operation and the intake pressure behavior has stabilized. This minimizes the occurrence of the above-mentioned false detections.

[0037] Incidentally, the above-described method for determining abnormalities in the intake pressure sensor 10 can also be applied to naturally aspirated (NA) engines that do not have a supercharger 3. However, in NA engines, the intake pressure is negative (a value smaller than atmospheric pressure p0), so it is desirable to use a negative value as the determination threshold Pth to determine abnormalities in the intake pressure sensor. In this case, by comparing the absolute value of the determination parameter PA with the absolute value of the determination threshold Pth, abnormalities in the intake pressure sensor can be determined in the same way as in the case of engine 1 equipped with a supercharger 3.

[0038] For example, in a naturally aspirated (NA) engine, suppose the reference value (=atmospheric pressure p0) is 100kPa, the measured intake pressure p1 is 90kPa, and the judgment threshold Pth is -2kPa. In this case, the judgment parameter PA is 90-100=-10kPa, but in absolute terms, |PA|>|Pth|. In engine 1 equipped with a supercharger 3, the intake pressure sensor 10 is judged to be normal when PA>Pth, that is, when |PA|>|Pth|. Following this judgment method, even in an NA engine, if |PA|>|Pth|, the intake pressure sensor can be judged to be normal.

[0039] Furthermore, in a naturally aspirated (NA) engine, for example, if the measured intake pressure p1 is 99 kPa, the judgment parameter PA becomes 99 - 100 = -1 kPa, and in absolute terms, |PA| < |Pth|. In engine 1 equipped with a supercharger 3, the intake pressure sensor 10 is judged to be abnormal when PA ≤ Pth, that is, when |PA| ≤ |Pth|. Following this judgment method, even in an NA engine, if |PA| ≤ |Pth|, it can be judged that the intake pressure sensor is abnormal.

[0040] In other words, the ECU 9, acting as the control unit, determines that the intake pressure sensor 10 is normal if the absolute value of the determination parameter PA is greater than the absolute value of the determination threshold Pth, and determines that the intake pressure sensor 10 is abnormal if the absolute value of the determination parameter PA is less than or equal to the absolute value of the determination threshold Pth. With this determination method, an abnormality in the intake pressure sensor 10 can be determined based on the determination parameter PA and the determination threshold Pth, whether the engine 1 is configured with a supercharger 3 or with a naturally aspirated (NA) configuration without a supercharger 3.

[0041] [3. Method for detecting abnormalities in generator-type engines] Figure 4 is a schematic diagram illustrating the relationship between engine speed, torque, and intake pressure in a naturally aspirated (NA) engine. Note that in an NA engine, the intake pressure is negative, so in Figure 4, the absolute value of the intake pressure is considered.

[0042] In the low-speed range where the engine speed is below a predetermined value, the amount of intake air into the cylinder head is small, and therefore the intake pressure in the intake manifold does not decrease easily. In this case, the margin between the judgment parameter PA and the judgment threshold Pth also becomes small. Intake pressure fluctuates due to individual differences in engines. Therefore, if the above margin is small, even if the intake pressure sensor is normal, if the intake pressure fluctuates due to individual differences in engines, |PA| < |Pth| may occur, and a false judgment that the intake pressure sensor 10 is abnormal may occur. In the high-speed range where the engine speed is above a predetermined value, the intake pressure drops significantly to the negative side, so the above margin also becomes larger. In this case, the influence of fluctuations in intake pressure due to individual differences in engines becomes less significant, and the above false judgment in the abnormality judgment of the intake pressure sensor becomes less likely to occur.

[0043] Therefore, in naturally aspirated (NA) engines, it is desirable to determine abnormalities in the intake pressure sensor as follows. For this explanation, we will use a generator-type engine, which is expected to be used for extended periods at low speeds, as an example of an NA engine.

[0044] Figure 5 is a schematic block diagram showing the main components of the diesel engine system 100, including the engine 1 and the generator 50. The engine 1 shown in Figure 5 has the same configuration as the engine 1 shown in Figures 1 and 2, except that it does not have a supercharger 3. The various sensors in Figures 1 and 2 (e.g., intake pressure sensor 10, exhaust temperature sensor 16) are connected to the ECU 9.

[0045] Furthermore, engine 1 has an engine speed sensor 31. The engine speed sensor 31 is a sensor that detects the rotational speed of engine 1 by detecting the rotation of the crankshaft of engine 1. The information detected by the engine speed sensor 31 (engine speed information) is output to the ECU 9.

[0046] Based on the information output from the various sensors described above, the ECU 9 can control the amount of fuel injected by the injector 8 and the opening degree (on / off) of the EGR valve 20 of the EGR device 18.

[0047] The generator 50 generates electricity using the driving force supplied from the engine 1. Such a generator 50 is connected to the crankshaft of the engine 1 via a belt or the like.

[0048] Figure 6 shows the relationship between the instructed injection amount from the ECU 9 to the injector 8 and the judgment parameter PA in the generator-type engine 1, both when the EGR valve 20 of the EGR device 18 is open and when it is closed. In the figure, the change in the judgment parameter PA based on the behavior of the intake pressure when the EGR valve 20 is open is shown by a solid line ("With EGR"), and the change in the judgment parameter PA based on the behavior of the intake pressure when the EGR valve 20 is closed is shown by a dashed line ("Without EGR").

[0049] In the generator-type engine 1, the ECU 9 controls the EGR valve 20 to open when the engine load (torque) is above a predetermined value, and to close when the engine load is below a predetermined value. When the EGR valve 20 is closed, the ECU 9 determines an abnormality in the intake pressure sensor 10 using the method described above. Here, the engine load is determined according to the rotational speed of the engine 1 detected by the engine speed sensor 31 and the instructed injection amount when instructing the injector 8 to inject fuel.

[0050] Under conditions where the EGR valve 20 is open, the judgment parameter PA approaches the threshold Pth in the region of low instructed injection volume (see graph for "With EGR"), and the margin between the judgment parameter PA and the threshold Pth becomes smaller. Therefore, in the abnormality detection of the intake pressure sensor 10, misjudgments due to fluctuations in intake pressure are more likely to occur. On the other hand, under conditions where the EGR valve 20 is closed, the judgment parameter PA moves away from the threshold Pth in the region of low instructed injection volume (see graph for "Without EGR"), and the margin between the judgment parameter PA and the threshold Pth becomes larger. Therefore, even if the intake pressure fluctuates, the above-mentioned misjudgments are less likely to occur. In other words, under conditions where the EGR valve 20 is closed, even if the intake pressure fluctuates due to individual differences in the engine while the engine 1 is driven at low rotational speeds, the abnormality detection of the intake pressure sensor 10 is less affected by the fluctuations in intake pressure. As a result, abnormalities in the intake pressure sensor 10 can be detected with high accuracy, and the above-mentioned misjudgments due to the influence of fluctuations in intake pressure can be reduced.

[0051] Furthermore, in this embodiment, the ECU 9 closes the EGR valve 20 when the engine load is below a predetermined value.

[0052] By setting the condition for closing the EGR valve 20 when the engine load is below a predetermined value, abnormality detection of the intake pressure sensor 10 can be performed in a region where the instructed injection amount is reliably small, that is, in a region where the difference (margin) between the judgment parameter PA and the judgment threshold Pth is reliably wide. This reliably reduces erroneous detections due to fluctuations in intake pressure when detecting abnormalities in the intake pressure sensor 10.

[0053] Although embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and it can be expanded or modified without departing from the spirit of the invention. [Industrial applicability]

[0054] The engine of the present invention can be used, for example, in work machines, generators, and the like. [Explanation of symbols]

[0055] 1 Engine 4. Intake pipe 5. Intake Manifold 6 Cylinder head 8. Injector (fuel injection device) 9 ECU (control unit) 10. Intake pressure sensor 18. EGR system (Exhaust gas recirculation system) 20 EGR valve (exhaust gas control valve) 31. Engine speed sensor

Claims

1. Cylinder head and, An intake manifold that supplies gas to the cylinder head, An intake pressure sensor for measuring the intake pressure in the intake manifold, An engine comprising a fuel injection device that injects fuel into the combustion chamber in the cylinder head, A control unit for determining an abnormality in the intake pressure sensor, The system further comprises an engine speed sensor for detecting the rotational speed of the engine, The control unit determines that the intake pressure sensor is normal if, after the amount of fuel injected by the fuel injection device exceeds a predetermined amount, the absolute value of the difference between the measured intake pressure measured by the intake pressure sensor and atmospheric pressure is greater than the absolute value of the determination threshold. Conversely, if the absolute value of the difference is less than or equal to the absolute value of the determination threshold, the control unit determines that the intake pressure sensor is abnormal. The predetermined amount is higher than the fuel injection amount when the engine is idle. The control unit prohibits the detection of an abnormality in the intake pressure sensor when the rotational speed of the engine is the idle rotational speed.

2. The engine according to claim 1, wherein the control unit determines an abnormality in the intake pressure sensor after a predetermined time has elapsed from the point in time when the fuel injection amount exceeds the predetermined amount.

3. The system further includes an exhaust gas recirculation device that returns a portion of the exhaust gas discharged from the cylinder head back to the intake pipe connected to the intake manifold, The exhaust gas recirculation device has an exhaust gas adjustment valve that adjusts the amount of exhaust gas supplied to the intake pipe, The engine according to claim 1 or 2, wherein the control unit determines an abnormality in the intake pressure sensor when the exhaust gas control valve is closed.

4. When the engine load is less than a predetermined value, the control unit closes the exhaust gas control valve. The engine according to claim 3, wherein the engine load is determined according to the rotational speed and the instructed injection amount when instructing the fuel injector to inject the fuel.

Images