JP4452534B2 - Abnormality detection device for supercharger in internal combustion engine - Google Patents

Description

  The present invention relates to an abnormality detection device for a supercharger in an internal combustion engine. More specifically, the present invention relates to supply by combining intake air delivered from a plurality of superchargers whose supercharging amount can be changed independently of the rotational speed of the internal combustion engine. The present invention relates to an abnormality detection device for a supercharger in an internal combustion engine.

  2. Description of the Related Art As a supercharger that improves the intake efficiency of an internal combustion engine (engine), there is an exhaust drive supercharger (turbocharger) that performs supercharging by using the flow of an exhaust flow. Moreover, the air sent out from a plurality of superchargers may join and be supplied.

  As a method of detecting an abnormality in the supercharger, the discharge intake pressure Pb of the compressor constituting the supercharger and the exhaust gas pressure Pg at the turbine inlet are detected, and the discharge intake pressure Pb is set to a set value from the exhaust gas pressure Pg. There is a method of determining that the state is abnormal when the state is lower than that and the state continues for a set time or longer (for example, see Patent Document 1).

The turbocharger also has a variable nozzle type turbocharger that adjusts the rotational speed of the turbine by changing the opening of the vane provided on the turbine side, and makes it possible to adjust the supercharging pressure by changing the rotational speed of the compressor. There is a feeder (variable nozzle type turbocharger).
Japanese Utility Model Publication No. 4-125635

  In an internal combustion engine having a plurality of superchargers, when the abnormality detection method described in Patent Document 1 is applied as it is, a pressure sensor that detects the discharge intake pressure Pb of the compressor for each supercharger, and a turbine inlet It is necessary to provide a pressure sensor for detecting the exhaust gas pressure Pg, which increases the number of parts.

  If an abnormality detection method is adopted that detects the difference between the actual boost pressure and the target boost pressure and determines that the difference exceeds the set value (judgment value), a single sensor will fail. Detection is possible. However, in an internal combustion engine equipped with a plurality of variable nozzle superchargers, even if an abnormality occurs in one supercharger and the supercharging capacity decreases, the variable nozzles of other superchargers are adjusted to achieve the target Control is performed to obtain a supercharging pressure. For example, if one of the two turbochargers becomes abnormal and the capacity is reduced by 20%, the other turbocharger is driven with the capacity increased by 20% to make up for it. As a whole, the target supercharging pressure is obtained, so no abnormality is detected.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide each supercharger in an internal combustion engine that supplies and supplies air fed from a plurality of superchargers capable of adjusting the output of a compressor. An object of the present invention is to provide an abnormality detection device for a supercharger in an internal combustion engine that can accurately detect an abnormality of the supercharger without providing a pressure sensor for each machine.

In order to achieve the above object, the invention according to claim 1 is a supercharger abnormality detection device in an internal combustion engine that supplies air fed from a plurality of superchargers, and compresses intake air. A plurality of superchargers having a rotation speed control means capable of changing the rotation speed of the compressor independently of the rotation speed of the internal combustion engine is provided. In addition, the actual supercharging amount detection means for detecting the supercharging pressure or the actual supercharging amount that is the intake air flow corresponding to the supercharging pressure, and the target supercharging amount calculation that calculates the target supercharging amount based on the operating state of the internal combustion engine And a reference value calculation means for calculating a command value of the rotation speed control means corresponding to the target supercharging amount as a reference value. Further, based on the same actual command value determined to bring the actual supercharging amount detected by the actual supercharging amount detection means closer to the target supercharging amount, the rotational speed control in the plurality of superchargers and a supercharging amount control means for controlling the means. Then, with said reference value, the difference between the actual command value, it is determined whether within a predetermined range, the abnormality judgment means for judging an abnormality when said difference is out of the range ing.

In the present invention, actual boost the actual boost amount detected by the sheet amount detector, feeding a plurality of over-so as to approach the target boost amount calculated by the target boost value calculating means based on the operation state of the internal combustion engine The rotational speed control means in the machine is controlled by the supercharging amount control means. The reference value calculation means calculates a command value of the rotation speed control means corresponding to the target supercharging amount as a reference value. The supercharging amount control means controls each supercharger based on the same actual command value. Then, the abnormality determining means determines whether or not a difference between the reference value and the actual command value is within a preset range, and determines that an abnormality is present when the difference is out of the range. Therefore, even if the actual supercharging amount is within the allowable error with respect to the target supercharging amount by the control by the supercharging amount control means, the difference between the reference value and the actual command value is out of the preset range. Therefore, the abnormality of the supercharger can be accurately detected without providing a pressure sensor for each supercharger.

  According to a second aspect of the present invention, in the first aspect of the present invention, the actual supercharging amount is a supercharging pressure, and the actual supercharging amount detecting means is provided downstream of the merging portion of the intake manifold. A supercharging pressure sensor. In the present invention, since the supercharging pressure is directly detected as the actual supercharging amount, the accuracy of abnormality detection is improved as compared with the case where the supercharging pressure is indirectly detected.

  According to a third aspect of the present invention, in the first aspect of the present invention, the actual supercharging amount is an intake air flow rate corresponding to a supercharging pressure, and the actual supercharging amount detecting means is upstream of the supercharger. The air flow meter is provided upstream of the merging portion of the intake passage on the side or at the merging portion of the intake manifold. In the present invention, the supercharging pressure is indirectly detected by the intake air flow rate.

  A fourth aspect of the present invention is the invention according to any one of the first to third aspects, further comprising abnormality treatment means for performing an abnormality treatment when the abnormality determination means determines that an abnormality has occurred. When determining the abnormality, the determination means also determines the degree of abnormality based on the difference between the reference value and the actual command value, and the abnormality treatment means performs an abnormality treatment according to the degree of abnormality. In this invention, the abnormality treatment means performs the abnormality treatment according to the degree of abnormality. Therefore, it is possible to suppress the deterioration of drivability until the abnormality is repaired, compared to the case where a uniform treatment is performed after the abnormality of the supercharger is detected.

The invention of claim 5 is the invention according to any one of claims 1 to 4, wherein the supercharger is configured to drive the compressor by a turbine driven by the exhaust, the The supercharging amount control means controls the opening degree of the vane provided in the turbine. In the present invention, since the turbocharger drives the compressor by the turbine driven by the exhaust gas, the power consumption is reduced as compared with the case where the compressor is driven by the motor. Further, since the variable nozzle type turbocharger is generally widely used, it can be implemented only by changing the program of the abnormality determination means.

Invention of claim 6 is the invention according to any one of claims 1 to 4, wherein the supercharger is configured to drive the compressor by shiftable motor, the supercharging The quantity control means controls the rotational speed of the motor. In the present invention, the compressor can be driven so as to achieve a target discharge air flow rate (discharge pressure) regardless of the operating state of the internal combustion engine. Therefore, compared with the variable nozzle type turbocharger, the target intake air amount can be supercharged even when the internal combustion engine rotates at a low speed.

  According to the present invention, in an internal combustion engine that supplies air that is fed from a plurality of superchargers that can adjust the output of a compressor, supercharging can be performed accurately without providing a pressure sensor for each supercharger. It is possible to detect machine abnormalities.

(First embodiment)
A first embodiment embodying the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram of a diesel engine system provided with an abnormality detection device.

  As shown in FIG. 1, a diesel engine 11 as an internal combustion engine includes a plurality of cylinders 12A and 12B, and the plurality of cylinders 12A and 12B are divided into two groups. Fuel injection valves 14 are attached to the cylinder heads 13A corresponding to the cylinders 12A in one group for each cylinder 12A, and the fuel injection valves 14 to the cylinder heads 13B corresponding to the cylinders 12B in the other group for each cylinder 12B. Is attached. The fuel injection valve 14 injects fuel supplied from a fuel injection pump (not shown) into each cylinder 12A, 12B.

  A common intake manifold 15 is connected to the cylinder heads 13A and 13B. The intake manifold 15 is connected to branched intake passages 17A and 17B branched from the main intake passage 16. That is, the intake air supplied from the main intake passage 16 is once branched by the branch intake passages 17A and 17B, and again merged at the junction of the intake manifold 15 and then supplied to the cylinders 12A and 12B. An air cleaner 16 a is provided at the inlet of the main intake passage 16.

  An exhaust manifold 18A is connected to the cylinder head 13A, and an exhaust manifold 18B is connected to the cylinder head 13B. The branch intake passage 17A is disposed so as to pass near the outlet of the exhaust manifold 18A, and the exhaust manifold 18A has an outlet connected to the exhaust passage 21A via the turbine 20A of the first supercharger 19A. The branch intake passage 17B is disposed so as to pass near the outlet of the exhaust manifold 18B, and the outlet of the exhaust manifold 18B is connected to the exhaust passage 21B via the turbine 20B of the second supercharger 19B.

  Exhaust gas purification devices 22 are provided in the exhaust passages 21A and 21B, respectively. In this embodiment, a DPNR (diesel, particulate, NOx, reduction system) is used as the exhaust purification device 22. A fuel addition valve 23 is provided between the turbines 20 </ b> A and 20 </ b> B and the exhaust purification device 22.

  The compressor 24A of the first supercharger 19A is interposed in the middle of the branch intake passage 17A, and the compressor 24B of the second supercharger 19B is interposed in the middle of the branch intake passage 17B. The first and second superchargers 19A and 19B are known variable nozzle turbochargers that are operated by an exhaust flow. The variable nozzle turbocharger drives the compressor using rotational torque generated in the turbine by the action of the exhaust flow as a drive source, and pumps air. The turbines 20 </ b> A and 20 </ b> B include a plurality of movable vanes in the nozzle portion, and the opening degree of the vanes can be changed by an actuator 40 such as a cylinder or a motor. The vane and the actuator 40 constitute a rotation speed control means that can change the rotation speed of the compressors 24A and 24B independently of the rotation speed of the diesel engine 11. The compressors 24A and 24B are provided with a rotational torque corresponding to the exhaust flow rate determined from the exhaust pressure at the outlets of the exhaust manifolds 18A and 18B and the opening degree of the vanes. The branch intake passages 17A and 17B are provided with an intercooler 25 on the downstream side of the first and second superchargers 19A and 19B.

  The diesel engine 11 is an engine with an exhaust gas recirculation device (EGR device), and exhaust circulation passages 26A and 26B are provided between the exhaust manifolds 18A and 18B and the intake manifold 15 to recirculate part of the exhaust gas to the intake system. It has been. One end of the exhaust circulation passage 26 </ b> A communicates with the exhaust manifold 18 </ b> A, and the other end communicates with the intake manifold 15 via the EGR valve 27. On the other hand, one end of the exhaust circulation passage 26 </ b> B communicates with the exhaust manifold 18 </ b> B, and the other end communicates with the intake manifold 15 via the EGR valve 27. The outlets of the exhaust circulation passages 26 </ b> A and 26 </ b> B are located at positions corresponding to the merging portions of the intake air from both branched intake passages 17 </ b> A and 17 </ b> B in the intake manifold 15.

  The EGR valve 27 is a negative pressure operation type in which a diaphragm is used as an actuator, and the actuator is connected to each output port of a negative pressure switching valve and a negative pressure adjusting valve (both not shown) through a passage. The negative pressure adjusting valve is a three-type solenoid valve whose opening degree is adjusted by duty control, its input port is connected to a vacuum pump (not shown), and its atmospheric port is open to atmospheric pressure. Atmospheric pressure is introduced into the input port of the negative pressure switching valve, and when the negative pressure switching valve is switched to the atmosphere introduction position, the EGR valve 27 is fully closed.

  The intake manifold 15 is provided with a supercharging pressure sensor 28 as an actual supercharging amount detecting means for detecting the actual supercharging amount. In this embodiment, the supercharging pressure sensor 28 is disposed at a merging portion of intake air from both branched intake passages 17A and 17B in the intake manifold 15. The supercharging pressure sensor 28 detects a supercharging pressure as an actual supercharging amount.

  The electronic control unit 29 that controls the diesel engine 11 brings the actual supercharging amount (actual supercharging pressure) detected by the supercharging pressure sensor 28 close to the target supercharging amount (target supercharging pressure). Based on the value, each supercharger 19A, 19B is controlled to constitute a supercharging amount control means for changing the rotational speed of the compressors 24A, 24B. The electronic control unit 29 also includes a target supercharging amount calculating means for calculating a target supercharging amount based on the operating state of the diesel engine 11 and a command value (vane) to the rotational speed control means corresponding to the target supercharging amount. And a reference value calculation means for calculating the opening degree as a reference value (basic vane opening degree). Further, the electronic control unit 29 constitutes an abnormality determining means for determining the abnormality of the first and second superchargers 19A and 19B, and an abnormality processing means for performing an abnormality treatment when the abnormality determining means determines that an abnormality has occurred. Is also configured. The abnormality determining means determines whether or not a difference between the reference value and the actual command value is within a preset range, and determines that an abnormality is present when the difference is out of the range.

  The electronic control unit 29 receives a detection signal from detection means for detecting an engine load, an operating state, and the like. In addition to the supercharging pressure sensor 28 as the detection means, for example, air flow meters 30A and 30B for detecting air flow rates in the branch intake passages 17A and 17B, a water temperature sensor 31 for detecting the water temperature in the diesel engine 11, and an accelerator, for example. There is an accelerator opening sensor 32 that detects the amount of pedal depression. The detection means includes an engine rotation speed sensor 33, an atmospheric pressure sensor 34, and the like.

  The electronic control unit 29 includes a microcomputer (hereinafter referred to as “microcomputer”) 35. The microcomputer 35 includes a memory (ROM and RAM) 36. The memory 36 includes an air flow meter 30A, 30B, a water temperature sensor 31, an accelerator opening sensor 32, an engine speed sensor 33, an atmospheric pressure sensor 34, etc. A map, an equation, and the like used for determining various command values (control values) to be commanded are stored. The map, the formula, and the like include, for example, a map, a formula, and the like that determine the fuel injection amount, the opening degree of the EGR valve 27, the opening degree of the vanes of the first and second superchargers 19A, 19B, and the like. The memory 36 stores a program for determining abnormality of the supercharger and performing abnormality treatment.

  The electronic control unit 29 obtains the actual boost pressure Pm from the detection signal of the boost pressure sensor 28, and when the actual boost pressure Pm is different from the target boost pressure Po, the actual boost pressure Pm is determined as the target boost pressure Po. The first and second superchargers 19A and 19B are controlled so as to approach each other. The electronic control unit 29 adjusts the supercharging pressure by feedback-controlling the vane opening. The electronic control unit 29 performs feedback control by proportional integral control (PI control), for example.

  The basic vane opening degree Cb corresponding to the target boost pressure Po is stored in the memory 36 as a map or a relational expression. On the other hand, the control amount of the vane actuator corresponding to each opening degree is also set in advance. Alternatively, it is stored in the memory 36 as a relational expression. And the basic vane opening degree Cb which is a reference value corresponding to the target supercharging pressure Po is calculated from a map, for example. Further, the correction amount Cfb added to the basic vane opening degree Cb is calculated from the difference between the actual supercharging pressure Pm and the target supercharging pressure Po. As an example of a method of calculating the correction amount Cfb, it is assumed here that the correction amount Cfb is calculated as the sum of a proportional term and an integral term. The proportional term is calculated as a value corresponding to the supercharging pressure difference | Pm−Po | by a predetermined one-dimensional map. The integral term is calculated as the sum of the value of the previous integral term and the value corresponding to the supercharging pressure difference | Pm−Po | by a predetermined one-dimensional map. The sum of the proportional term and the integral term becomes the correction amount Cfb, the sum of the basic vane opening and the correction amount is calculated, and the final vane opening Cn = Cb + Cfb corresponding to the actual command value is determined. When the final vane opening degree Cn is determined, the control amount of the current actuator corresponding to this is determined and output. As a result, the vane moves from the current position, that is, from the last final vane opening to the position of the current final vane opening Cn.

  The electronic control unit 29 calculates the target boost pressure Po based on the operating state of the diesel engine 11 and calculates the absolute difference between the actual boost pressure Pm detected by the boost pressure sensor 28 and the target boost pressure Po. The first abnormality determination is performed based on the value | Pm−Po |. In this first abnormality determination, the electronic control unit 29 performs the first and second overloads when the absolute value | Pm−Po | is greater than or equal to a predetermined determination value α for a predetermined time To. The feeders 19A and 19B are determined to be abnormal. The determination value α is a value set in consideration of the design tolerance of the components of the turbocharger. Although the predetermined time To depends on the vehicle type and the engine displacement, it is set to a value between 2 seconds and 10 seconds, for example, a few seconds.

  In addition, the electronic control unit 29 makes a second abnormality determination based on the difference between the reference value and the actual command value. In the second abnormality determination, the electronic control unit 29 determines that the difference between the basic vane opening Cb as the reference value and the final vane opening Cn (= Cb + Cfb) corresponding to the actual command value is within a preset range. It is determined whether or not there is an abnormality, and it is determined that there is an abnormality when the difference is out of the range.

  The electronic control unit 29 commands the same control amount to the actuators 40 of the superchargers 19A and 19B. The reference value is calculated on the assumption that both superchargers 19A and 19B are normal. Therefore, when there is an abnormality in one of the superchargers 19A and 19B, in order to obtain the same opening as the final vane opening Cn corresponding to the actual command value, it is necessary to increase the actual command value, and the difference is It will deviate from the preset range.

  When the electronic control unit 29 determines the second abnormality, the electronic control unit 29 determines the degree of abnormality, specifically, whether one of the supercharger vanes is fixed in a fully closed state or fixed in a fully opened state. Judgment is made. Whether the vane is fixed in the fully closed state is determined by comparing the correction amount Cfb with the lower limit threshold L1, and when the correction amount Cfb is less than the lower limit threshold L1, the vane is fixed in the fully closed state. Judge. Whether the vane is fixed in the fully opened state is determined by comparing the correction amount Cfb with the upper limit threshold L2, and when the correction amount Cfb exceeds the upper limit threshold L2, the vane is fixed in the fully opened state. Judge.

  When the electronic control unit 29 determines that it is stuck in the fully closed state (the degree of abnormality is high), the engine is put into a protective operation at the first level (high level) as an abnormality treatment. Switch. In addition, when it is determined that it is stuck in the fully opened state (the degree of abnormality is low), the engine is switched to the protection operation at the second level (low level) as an abnormality treatment.

  Switching the engine to a high-level protection operation means that the operation of the diesel engine 11 is not completely stopped, but can be run at a low speed (for example, the maximum speed is 20 km / h). . Further, switching the engine to a low-level protection operation means that the vehicle can travel at a high speed (for example, the maximum speed is 100 km / h), but the acceleration state is slowed down. Making the acceleration state dull means that high load and high rotation are prohibited. For example, it takes about 30 seconds to accelerate to 100 km / h in about 10 seconds before switching.

Next, the operation of the apparatus configured as described above will be described.
The electronic control unit 29 grasps the operating state from detection signals from the air flow meters 30A and 30B, the water temperature sensor 31, the accelerator opening sensor 32, the engine rotation speed sensor 33, the atmospheric pressure sensor 34, and the like. Then, the fuel injection amount, the fuel injection timing, and the exhaust ring flow rate are calculated so as to obtain an appropriate combustion state corresponding to the grasped engine operating state (load state), and the fuel injection pump and the EGR valve 27 are controlled. . Further, the electronic control unit 29 calculates a target supercharging pressure (target supercharging amount) Po based on the detected value of the accelerator opening sensor 32, the detected value of the engine speed sensor 33, and the opening of the EGR valve 27, for example. Then, the vane opening degree of the turbines 20A and 20B corresponding to the target supercharging pressure Po is calculated. And the command signal for maintaining the said vane opening degree is output to the actuator 40 which operates a variable vane. The electronic control unit 29 outputs a common command signal to the actuators 40 of both turbines 20A and 20B.

  The electronic control unit 29 performs an abnormality determination process for the supercharger and a control for performing the abnormality treatment according to the flowcharts of FIGS. 2 and 3. This control is performed in a predetermined control cycle set in advance. The predetermined cycle is, for example, a dozen milliseconds.

  The electronic control unit 29 reads the detection signal of the supercharging pressure sensor 28 in step S1, obtains the actual supercharging pressure Pm, and calculates the absolute value of the difference between the target supercharging pressure Po and the actual supercharging pressure Pm in step S2. To do. In step S3, the electronic control unit 29 determines whether or not the absolute value | Po−Pm | of the difference is larger than a determination value α. The electronic control unit 29 proceeds to step S4 if | Po−Pm | is larger than the determination value α in step S3, and increments the count value of the first counter by 1 in step S4, and then proceeds to step S5. The electronic control unit 29 proceeds to step S5 if | Po−Pm | is equal to or smaller than the determination value α in step S3.

  In step S5, the electronic control unit 29 determines whether or not the count value of the first counter is greater than or equal to the set value. The set value is set to a value corresponding to the count value when the first abnormality continues for a predetermined time To. For example, if the predetermined time To is 4 seconds and the period of the abnormality determination process is 16 milliseconds, the setting value is 250.

  If the count value is greater than or equal to the set value in step S5, the electronic control unit 29 proceeds to step S6, determines that the first abnormality has occurred, and then proceeds to step S7. If the count value is less than the set value in step S5, the process proceeds to step S7. When the first and second superchargers 19A and 19B become abnormal, there is a high probability that it will be determined as the first abnormality.

  Next, after calculating the correction amount Cfb in step S7, the electronic control unit 29 proceeds to step S8 and determines whether or not the correction amount Cfb is less than the lower limit threshold L1. The calculation of the correction amount Cfb is performed by obtaining the sum of the proportional term and the integral term calculated by the above calculation method.

  If the correction amount Cfb is less than the lower limit threshold L1 in step S8, the electronic control unit 29 proceeds to step S9, increments the count value of the second counter by 1 in step S9, and then proceeds to step S10. If the correction amount Cfb is greater than or equal to the lower limit threshold L1 in step S8, the electronic control unit 29 proceeds to step S10. In step S10, the electronic control unit 29 determines whether or not the count value of the second counter is greater than or equal to the set value. The set value is set to a value corresponding to the count value when the second abnormality continues for a predetermined time To.

  If the count value is greater than or equal to the set value in step S10, the electronic control unit 29 proceeds to step S11, determines that the fully closed fixation is abnormal, and then proceeds to step S12. In step S12, the electronic control unit 29 switches the operation of the diesel engine 11 to the first protection operation level. Specifically, a flag indicating that the operation of the diesel engine 11 is performed at the first protection operation level is turned ON. When this flag is ON, the electronic control unit 29 operates the diesel engine 11 at the first protection operation level.

  Next, the electronic control unit 29 proceeds to step S13, and determines whether or not a predetermined time To has elapsed since the reset of the first counter, the second counter, and the third counter. If the predetermined time To has elapsed in step S13, the electronic control unit 29 proceeds to step S14, and after resetting each counter (first counter, second counter, and third counter) in step S14, the abnormality determination process is terminated. To do. If the predetermined time To has not elapsed in step S13, the electronic control unit 29 ends the abnormality determination process without resetting each counter.

  If the count value is less than the set value in step S10, the electronic control unit 29 proceeds to step S15, and determines in step S15 whether Cfb exceeds the upper limit threshold L2. If the correction amount Cfb exceeds the upper limit threshold L2 in step S15, the process proceeds to step S16, and after the count value of the third counter is incremented by 1 in step S16, the process proceeds to step S17. If it is determined in step S15 that the correction amount Cfb is equal to or less than the upper limit threshold L2, the process proceeds to step S17.

  If the count value is greater than or equal to the set value in step S17, the electronic control unit 29 proceeds to step S18, determines that the fully-open fixation is abnormal, and then proceeds to step S19. In step S19, the electronic control unit 29 switches the operation of the diesel engine 11 to the second protection operation level, and then proceeds to step S13. Switching the operation of the diesel engine 11 to the second protection operation level is to turn on a flag indicating that the operation of the diesel engine 11 is performed at the second protection operation level in this embodiment. When this flag is ON, the electronic control unit 29 operates the diesel engine 11 at the second protection operation level. If the count value is less than the set value in step S17, the electronic control unit 29 proceeds to step S13.

This embodiment has the following effects.
(1) Correction when the abnormality detection device performs control so that the actual supercharging pressure Pm (actual supercharging amount) detected by the actual supercharging amount detection means approaches the target supercharging pressure Po (target supercharging amount) It is determined whether or not the amount Cfb is within a preset range, and when the correction amount Cfb is out of the range, it is determined that there is an abnormality. Therefore, despite the presence of an abnormal (failure) supercharger, the other superchargers are adjusted in capacity so as to compensate for the abnormal supercharger, and the actual supercharging pressure Pm becomes the target supercharging pressure Po. On the other hand, an abnormality can be detected even when it is within the allowable range. That is, in an internal combustion engine that supplies and feeds air sent from a plurality of superchargers that can adjust the output of the compressor, it is possible to accurately detect a supercharger without providing a pressure sensor for each supercharger. Can be detected.

  (2) The supercharging pressure is directly detected by the supercharging pressure sensor 28 as the actual supercharging amount, and the supercharging pressure sensor 28 is provided on the downstream side of the junction portion of the intake manifold 15. Therefore, the accuracy of abnormality detection is improved compared to the case where the supercharging pressure is detected indirectly.

  (3) The abnormality determination means determines the abnormality due to the fully closed fixation and the abnormality due to the fully open fixation by comparing the correction amount Cfb with the lower limit threshold L1 and the upper limit threshold L2. Therefore, it is possible to deal with the abnormality more accurately.

  (4) When determining the abnormality, the abnormality determination means also determines the degree of abnormality based on the correction amount Cfb, and the abnormality treatment means performs an abnormality treatment according to the degree of abnormality. Therefore, it is possible to suppress the deterioration of drivability until the abnormality is repaired, compared to the case where a uniform treatment is performed after the abnormality of the supercharger is detected.

  (5) The superchargers 19A and 19B are variable nozzle turbochargers that drive the compressors 24A and 24B by a turbine driven by exhaust gas. Therefore, since exhaust gas is used as power for driving the turbine of the supercharger, power consumption is reduced as compared with the case where the compressors 24A and 24B are driven by motors. Further, since the variable nozzle type turbocharger is generally widely used, it can be implemented only by changing the program of the abnormality determination means.

(6) Since the correction amount Cfb is calculated in consideration of the operation of the EGR valve 27, the abnormality of the supercharger can be detected without any trouble even when the EGR device is operating.
(Second Embodiment)
Next, a second embodiment will be described with reference to FIG. In this embodiment, instead of detecting the supercharging pressure as the actual supercharging amount, the actual supercharging pressure Pm is estimated by detecting the intake flow rate corresponding to the supercharging pressure, and the superchargers 19A and 19B The point that the compressor is driven by a motor is greatly different from that of the first embodiment. Parts similar to those of the above-described embodiment are given the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the branch intake passages 17A and 17B are arranged so as to pass through locations away from the outlets of the exhaust manifolds 18A and 18B, respectively. The outlets of the exhaust manifolds 18A and 18B are directly connected to the exhaust passages 21A and 21B, respectively. The main intake passage 16 is provided with an air flow meter 16b on the downstream side of the air cleaner 16a.

  The compressors 24A and 24B of the superchargers 19A and 19B are interposed in the middle of the branch intake passages 17A and 17B, respectively. Each compressor 24A, 24B is configured to be driven by a motor 37. The motor 37 is configured to be capable of speed change control by an inverter 38. The motor 37 and the inverter 38 constitute a rotation speed control means that can change the rotation speed of the compressors 24A and 24B independently of the rotation speed of the diesel engine 11.

  The electronic control unit 29 constitutes reference value calculation means for calculating a command value (motor rotation speed) to the rotation speed control means as a reference value (basic motor rotation speed). The electronic control unit 29 adjusts the supercharging pressure by feedback-controlling the power supplied to the motor 37 via the inverter 38. The electronic control unit 29 performs feedback control by proportional integral control (PI control), for example.

  The electronic control unit 29 calculates the rotational speed of the motor 37 corresponding to the target supercharging amount (target supercharging pressure) Po as the basic motor rotational speed (reference value) MCb. Corresponding to the target boost pressure Po, the basic motor rotational speed MCb is stored in the memory 36 as a map or a relational expression, while the control amount (for example, supplied power amount) of the motor 37 corresponding to each rotational speed is also stored. Are set in advance and stored in the memory 36 as a map or a relational expression. Then, the basic motor rotational speed MCb, which is a reference value corresponding to the target boost pressure Po, is calculated from a map, for example. Further, the correction amount MCfb added to the basic motor rotational speed MCb is calculated from the difference between the actual supercharging pressure Pm and the target supercharging pressure Po. As an example of a method for calculating the correction amount MCfb, it is assumed here that the correction amount MCfb is calculated as the sum of a proportional term and an integral term. The proportional term is calculated as a value corresponding to the supercharging pressure difference | Pm−Po | by a predetermined one-dimensional map. The integral term is calculated as the sum of the value of the previous integral term and the value corresponding to the supercharging pressure difference | Pm−Po | by a predetermined one-dimensional map. The sum of the proportional term and the integral term becomes the correction amount MCfb, the sum of the basic motor rotation speed and the correction amount is calculated, and the final motor rotation speed MCn = MCb + MCfb corresponding to the actual command value is determined. When the final motor rotational speed MCn is determined, the control amount of the current motor 37 corresponding to the final motor rotational speed MCn is determined, and a corresponding command signal is output to the inverter 38. The speed of the motor 37 changes from the current rotational speed, that is, the previous final motor rotational speed to the current final motor rotational speed MCn.

  The intake manifold 15 is provided with an air flow meter 39 as actual supercharging amount detection means. In this embodiment, the air flow meter 39 is disposed at a merge portion of intake air from both branched intake passages 17A and 17B in the intake manifold 15. The air flow meter 39 indirectly detects the supercharging pressure as the actual supercharging amount from the intake air flow rate.

  Also in this embodiment, the turbocharger abnormality detection and abnormality treatment are performed in substantially the same manner as in the first embodiment. That is, in the flowcharts of FIG. 2 and FIG. 3, the correction amount MCfb is used instead of the correction amount Cfb, and the steps are substantially the same except that the lower limit threshold value L1 in step S8 and the upper limit threshold value L2 in step S15 are different.

This embodiment has the following effects in addition to substantially the same effects as (1), (3), (4), and (6) of the first embodiment.
(7) The first and second superchargers 19A and 19B are configured to drive the compressors 24A and 24B by a motor 37 capable of shifting control. Therefore, the compressors 24 </ b> A and 24 </ b> B can be driven so as to achieve a target discharge air flow rate (discharge pressure) regardless of the operation state of the diesel engine 11. Therefore, compared to the variable nozzle turbocharger, the target intake air amount can be supercharged even when the diesel engine 11 rotates at a low speed.

  (8) Since it is not necessary to arrange part of the branch intake passages 17A and 17B so as to pass through the vicinity of the outlets of the exhaust manifolds 18A and 18B, the degree of freedom of arrangement of the branch intake passages 17A and 17B increases.

  (9) Since the main intake passage 16 is provided with an air flow meter 16b for measuring the intake air quantity upstream from the first and second superchargers 19A, 19B, the air flow meters 30A, 17B are provided in the branch intake passages 17A, 17B. The number of parts can be reduced as compared with the embodiment in which 30B is provided.

The embodiment is not limited to the above, and may be embodied as follows, for example.
○ The first abnormality determination may be omitted. That is, steps S1 to S6 in the flowchart of FIG. 2 are omitted, and abnormality detection is performed only by the second abnormality determination.

  As an abnormality treatment to be performed after the second abnormality determination, only the first protection operation level may be provided without providing the first protection operation level and the second protection operation level. In other words, the operation level of the internal combustion engine is changed to the first protection operation level (high protection operation level) as an abnormality treatment both when the fully closed fixation is abnormal and when the fully open fixation is abnormal.

〇 The abnormality treatment after abnormality detection is not limited to the treatment that changes the operation level.
* You may apply not only to the diesel engine 11 but to another internal combustion engine (for example, gasoline engine).

O The timing of abnormality detection may be set so as to avoid a transient state when the operating conditions of the diesel engine 11 change greatly, such as sudden acceleration / deceleration. In this case, erroneous detection can be suppressed.
O The abnormality detection time may be performed only when the exhaust gas recirculation device is not operating (for example, during idle operation or fully open operation). In this case, calculation of the target boost pressure Po is simplified.

The internal combustion engine is not limited to an engine with an exhaust gas recirculation device, and may be applied to an internal combustion engine that is not equipped with an exhaust gas recirculation device.
〇 When applied to an internal combustion engine that is not equipped with an exhaust gas recirculation device, the actual supercharging amount detection means is provided with an air flow meter that indirectly detects the supercharging pressure based on the intake flow rate. The air flow meter 16b provided in the intake passage 16 may also serve as the actual supercharging amount detection means. In this case, the number of parts can be reduced by using the detection means for detecting the intake flow rate necessary for engine control without providing the actual supercharging amount detection means (supercharging pressure sensor).

  In the first embodiment, the air flow meter 39 may be used in place of the supercharging pressure sensor 28, or in the second embodiment, the supercharging pressure sensor 28 may be used in place of the air flow meter 39. When the supercharging pressure sensor 28 detects the abnormality of the supercharger during the operation of the exhaust gas recirculation device because the effect of EGR on the detected supercharging amount (supercharging pressure) is less than that of the air flow meter 39. Is preferably provided with a supercharging pressure sensor 28.

  〇 Since the pressure in the intake manifold 15 is substantially constant, the supercharging pressure sensor 28 is not limited to the intake merging portion, and any position can be used as long as the pressure in the intake manifold 15 can be detected. Good.

  The set values of the first counter, the second counter, and the third counter used at the time of abnormality determination may not be equal to the value obtained by dividing the predetermined time To by the abnormality determination period. For example, the correction values Cfb and MCfb may be small in spite of an abnormality due to variation in the operating state, and therefore the set value may be slightly reduced (for example, 1%).

  As an abnormality determination method, it may be configured that an abnormality is determined when a state that satisfies the comparison condition with the determination value α, the lower limit threshold L1, and the upper limit threshold L2 in steps S3, S8, and S15 continues for a predetermined number of times. . For example, when the comparison condition is satisfied, the count value of the counter is incremented by 1 (increment), and when the comparison condition is not satisfied, the counter is reset. The predetermined number of times is, for example, a value obtained by dividing the predetermined time To by the abnormality determination cycle or a value slightly smaller (for example, 1%) than the value.

  In the first embodiment, the intake air flow rate upstream of the first and second superchargers 19A and 19B may be detected by the air flow meter 16b provided in the main intake passage 16. In the second embodiment, the intake air flow rate upstream of the first and second superchargers 19A and 19B may be detected by 30A and 30B provided in the branch intake passages 17A and 17B.

The exhaust purification device 22 is not limited to the DPNR.
The left and right exhaust circulation passages 26A and 26B may be configured to communicate with each other.
O You may apply this invention in the internal combustion engine provided with three or more superchargers.

The following technical idea (invention) can be understood from the embodiment.
(1) In the invention according to any one of claims 1 to 6, the internal combustion engine includes an exhaust gas recirculation device, and the control means sets the actual supercharging amount to the target supercharging amount in consideration of the EGR amount. Control to bring them closer.

  (2) In the invention according to any one of claims 1 to 6, the internal combustion engine is provided with an exhaust gas recirculation device, and the abnormality determination means performs supercharging in a state where the exhaust gas recirculation device is not operated. Detect machine abnormalities.

The schematic block diagram of the diesel engine system of 1st Embodiment. The flowchart for demonstrating the abnormality detection procedure of a supercharger. The flowchart for demonstrating the abnormality detection procedure of a supercharger. The schematic block diagram of the diesel engine system of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Diesel engine, 15 ... Intake manifold, 19A, 19B ... Supercharger, 20A, 20B ... Turbine, 24A, 24B ... Compressor, 28 ... Supercharging pressure sensor as actual supercharging amount detection means, 29 ... Target supercharging An electronic control unit as an amount calculation means, a reference value calculation means, a supercharging amount control means, an abnormality determination means and an abnormality processing means, 37... A motor constituting a rotational speed control means, 38. Air flow meter as detection means, 40... Actuator constituting rotation speed control means.

Claims (6)

An abnormality detection device for a supercharger in an internal combustion engine that supplies air fed from a plurality of superchargers,
A plurality of superchargers having rotation speed control means capable of changing the rotation speed of the compressor for compressing intake air independently of the rotation speed of the internal combustion engine;
An actual supercharging amount detection means for detecting an actual supercharging amount that is a supercharging pressure or an intake flow rate corresponding to the supercharging pressure;
Target supercharging amount calculating means for calculating a target supercharging amount based on the operating state of the internal combustion engine;
A reference value calculating means for calculating a command value of the rotational speed control means corresponding to the target supercharging amount as a reference value;
Based on the same actual command value determined to bring the actual supercharging amount detected by the actual supercharging amount detection means closer to the target supercharging amount, the rotational speed control means in the plurality of superchargers a supercharge amount control means for controlling,
And the reference value, the difference between the actual command value, it is determined whether or not within a preset range, the difference is provided with an abnormality determining means for determining an abnormality when deviating from the scope An abnormality detection device for a supercharger in an internal combustion engine.   2. The supercharging in the internal combustion engine according to claim 1, wherein the actual supercharging amount is a supercharging pressure, and the actual supercharging amount detection means is a supercharging pressure sensor provided downstream of the junction portion of the intake manifold. Anomaly detection device.   The actual supercharging amount is an intake air flow rate corresponding to a supercharging pressure, and the actual supercharging amount detecting means is provided upstream of the merging portion of the intake passage upstream of the supercharger or at the merging portion of the intake manifold. The supercharger abnormality detection device for an internal combustion engine according to claim 1, wherein the abnormality detection device is an air flow meter.   When the abnormality determination unit determines that an abnormality is present, the abnormality determination unit includes an abnormality treatment unit. The abnormality determination unit determines the degree of abnormality based on a difference between the reference value and the actual command value when determining abnormality. The abnormality detection device for a supercharger in an internal combustion engine according to any one of claims 1 to 3, wherein the abnormality treatment means performs an abnormality treatment according to a degree of abnormality. The supercharger is configured to drive the compressor by a turbine driven by exhaust gas, and the supercharging amount control means controls an opening degree of a vane provided in the turbine. The abnormality detection apparatus for the supercharger in the internal combustion engine according to any one of the above. The said supercharger is a structure which drives the said compressor with the motor which can be changed, and the said supercharging amount control means controls the rotational speed of the said motor. An abnormality detection device for a supercharger in an internal combustion engine.

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