JP2012251484A - Supercharge-assist method for internal combustion engine and the internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a supercharge-assist method for an internal combustion engine capable of efficiently controlling supercharge-assist by precisely determining the end timing of the supercharge-assist using compressed gas in an accumulated gas container, in the internal combustion engine using the gas stored in the accumulated gas container for the supercharge-assist, and to provide the internal combustion engine.SOLUTION: A supply amount We of gas C to be supplied into a cylinder is calculated by subtracting an in-passage accumulation amount Wm of the gas C accumulated in an intake manifold 11a and in an intake manifold-side passage from the intake manifold 11a to a flow path switching device 30, from a discharge amount Wt of the compressed gas C from an accumulated gas container 27. When an air excess ratio λc calculated on the basis of the supply amount We of the gas C and a fuel supply amount Qin becomes equal to or less than a preset end limit air excess ratio λ2, the supercharge-assist is terminated even before an elapsed time Ti of the supercharge-assist reaches a preset end time Ts.

Description

  The present invention relates to a supercharging assist method for an internal combustion engine and an internal combustion engine that can increase the EGR rate by supplying gas stored in a gas storage container into a cylinder in a transient state of the internal combustion engine.

  In EGR (exhaust gas recirculation) for reducing NOx (nitrogen oxide) in exhaust gas of an internal combustion engine such as a diesel engine, there are a high pressure EGR method and a low pressure EGR method in an internal combustion engine equipped with a supercharging system. In this high pressure EGR system, for example, as shown in FIG. 9, in an internal combustion engine 1X equipped with a high pressure EGR system, an EGR passage 17 is provided closer to the engine body 11 than the turbocharger 14, and the engine body The EGR gas Ge is recirculated from the 11 exhaust manifolds 11 b to the intake manifold 11 a via the EGR passage 17. Further, in the low pressure EGR system, for example, as shown in FIG. 10, in the internal combustion engine 1Y provided with the low pressure EGR system, an EGR passage 17 is provided on the opposite side of the engine body 11 from the turbocharger 14. The EGR gas Ge is recirculated from the downstream side of the turbine 14b to the upstream side of the compressor 14a via the EGR passage 17.

  In any of these EGR systems, the MAF control system is generally used to control the amount of EGR gas. In this MAF control method, if the amount of fresh air (air amount) sucked into the cylinder of the engine without EGR is Mo and the amount of fresh air sucked into the cylinder by performing EGR is Me, it is recirculated. Since the EGR gas amount Megr is Megr = Mo−Me, the EGR gas amount Megr is controlled by controlling the fresh air amount Me based on the valve opening degree of the EGR valve 21 based on this.

  That is, based on the data map of the fresh air amount Me created by setting the fresh air amount Me for each engine operating state in advance using the engine rotational speed Ne and the fuel load Q as parameters, The target fresh air amount Met is calculated from the rotational speed Ne and the fuel load Q, and the actual fresh air amount Me is controlled to become the target fresh air amount Met, thereby controlling the EGR gas amount Megr. Yes.

  However, when a turbocharger is used, the exhaust gas energy (enthalpy) is used for supercharging, so it is impossible to eliminate the response delay (turbo lag) of the turbocharger. The MAF control method has the following problems due to the turbo lag. In a transient operation state in which the load increases rapidly due to the turbo lag, the supercharging pressure does not increase to the pressure set during steady operation, so the intake air amount of the engine decreases. In other words, even an engine with a turbo-type supercharger has the same intake air amount as a non-supercharged engine.

  Therefore, the target EGR amount set under the steady operation condition cannot be achieved, and as shown in FIG. 11, the NOx emission amount increases when performing a rapid transient operation. Further, in order to limit the amount of soot generated, smoke limit control is performed in which the amount of fuel input is suppressed in a region where the soot does not increase when the supercharging pressure does not rise above a certain level. As a result, as shown in FIGS. 12 and 13, both the fuel injection amount Q and the air amount (Mo, Me) are suppressed as indicated by the dotted lines, and there is a problem that the power during acceleration is suppressed. For this reason, during transient operation in which the load increases rapidly during acceleration or the like, an increase in NOx emissions and a deterioration in fuel consumption occur.

  On the other hand, in the case of using a mechanical supercharger that performs supercharging by directly driving the supercharger by an engine crankshaft or the like, the delay in the supercharging response can be eliminated, but the engine speed is determined. However, there is a problem that fuel efficiency deteriorates because the amount of supercharging is determined regardless of the amount of fuel and the amount of work required for driving is large.

  As a countermeasure, in recent years, an internal combustion engine 1Z having a storage gas supply system as shown in FIG. 14 has been studied, and in this storage gas supply system, a part Gp of the exhaust gas G discharged from the internal combustion engine 1Z. The mixed gas C mixed with air Aa is compressed by a positive displacement compressor (exhaust compressor) 25 to increase the pressure, and the increased mixed gas C is stored in a gas storage container (pressure container) 27 to release electromagnetic waves in a transient state. The valve 36 is opened and the mixed gas C is discharged to the intake passage 12 downstream of the intake valve (intake throttle) 35 via the pressure regulating valve 29, whereby the amount of intake air into the cylinder of the internal combustion engine 1Z is supercharged. There has been proposed a supercharging control device that increases the same level as an attached engine, reduces NOx by the effect of EGR, and solves the problem of turbo lag (see, for example, Patent Document 1).

  When this storage gas supply system is adopted, the supercharging pressure is increased by releasing the gas mixture C pressurized during the transition into the intake passage 12 of the engine 1Z, thereby increasing the amount of air into the cylinder. Can increase the amount of fuel. As a result, acceleration performance is improved and soot discharge can be suppressed. Further, since the supercharging pressure is higher than the internal pressure of the exhaust manifold 11b, the pumping loss of the internal combustion engine 1Z is reduced, and the fuel efficiency can be improved.

  However, although this storage gas supply system is an extremely effective means for improving the acceleration performance of the engine, both the supply amount of the intake air supplied into the cylinder of the engine and the supply amount of the gas from the storage container are reduced. There is a problem that it cannot be measured.

  In other words, the gas released from the gas storage container is used not only to be sucked into the engine cylinder but also to increase the internal pressure (supercharging pressure) of the intake manifold. The total amount is not the amount supplied into the cylinder.

  If the supply amount of gas sucked into the cylinder and the supply amount of intake air cannot be measured correctly, the total amount of exhaust gas and the emission amount (unit of mass) of NOx, HC, CO, etc., whose emission is regulated are accurately estimated. The problem that it becomes impossible, the problem that the control which keeps the excess air ratio (lambda) constant by optimizing the fuel supply amount supplied in a cylinder, etc. arise.

  In particular, in an internal combustion engine including a gas storage supply system, when switching between a normal intake line and a supercharging auxiliary line connected to a gas storage container, for example, an intake air amount sensor (MAF sensor: If a mass air flow sensor) is provided in the intake passage (on the normal line) on the upstream side of the flow path switching device, the amount of accumulated gas released cannot be measured during supercharging assist operation for supplying gas from the gas storage container . On the other hand, when the intake air amount sensor is installed in the intake passage on the downstream side of the flow path switching device, the amount of gas released from the gas storage container to the intake manifold can be measured. Since the amount of gas supplied to the cylinder and the amount of gas accumulated in the intake manifold in order to increase the internal pressure of the intake manifold are included, it is impossible to accurately measure the supply amount sucked into the cylinder. .

JP 2011-21558 A

  The present invention has been made in view of the above-described situation, and an object of the present invention is to store a part of exhaust gas, air, and any one of these mixed gases in a gas storage container using a gas compression device. In an internal combustion engine that suppresses NOx emission in a transient state and improves acceleration performance in a transient state where the load suddenly increases, the gas in the gas storage container is used. An object of the present invention is to provide a supercharging assistance method for an internal combustion engine and an internal combustion engine capable of accurately determining the end timing of supercharging assistance and efficiently controlling supercharging assistance.

  In order to achieve the above object, a supercharging assist method for an internal combustion engine according to the present invention comprises an EGR passage for recirculating a part of exhaust gas of the internal combustion engine into a cylinder, a part of exhaust gas of the internal combustion engine, A gas compression device for compressing air and any of these mixed gases, a gas storage container for storing the gas compressed by the gas compression device, and a flow path switching device between the gas storage container and the intake system passage In the supercharging assist method for an internal combustion engine provided with a storage gas supply passage connected via an intake manifold, from the temperature and pressure of the gas inside the intake manifold, the intake manifold and the intake manifold to the flow path switching device Calculate the accumulated amount of the gas accumulated in the intake system passage, subtract the accumulated amount in the passage from the amount of gas released from the gas storage container via the flow path switching device, Sirin The supply amount of the gas supplied to the inside is calculated, an excess air ratio is calculated from the supply amount and the fuel supply amount, and the calculated excess air ratio is less than or equal to a preset end limit excess air ratio. The supercharging assistance using the gas from the gas storage container is terminated even when the elapsed time of the supercharging assistance has not passed the preset end time. It is.

  According to this method, the supply amount of gas supplied into the cylinder in a transient state is accurately grasped, and the supercharging assist stop condition is determined by the excess air ratio that is the relationship between the air amount and the fuel supply amount. Since it can set, the supercharging assistance method in the supercharging assistance system by the gas from a storage gas container can be optimized.

  In other words, it is possible to accurately grasp the amount of accumulated gas supplied to the cylinder of the engine in the case of supercharging assistance and the amount of intake air in the case of normal control, and the total amount of exhaust gas and emission are regulated. Emissions of NOx, HC, CO, etc. can be accurately estimated. In addition, the amount of fuel supplied into the cylinder can be optimally controlled to keep the excess air ratio at a constant value.

  In the above-described supercharging assist method for an internal combustion engine, an air excess rate calculated from an intake air amount, an EGR amount measured by an intake air amount sensor disposed in the intake passage, and a fuel supply amount is set in advance. When supercharging assistance using the gas from the gas storage container is started when the limit excess ratio is reached, the supercharging assistance start condition is the excess air ratio that is the relationship between the air amount and the fuel supply amount. Since it can set, the supercharging assistance method in the supercharging assistance by the pressure-accumulated gas from the gas storage container can be optimized.

  An internal combustion engine for achieving the above object is an internal combustion engine capable of implementing the above-described supercharging assist method of the internal combustion engine, and an EGR passage for recirculating a part of the exhaust gas of the internal combustion engine into the cylinder. A gas compression device that compresses a part of the exhaust gas of the internal combustion engine, air, and any of these mixed gases, a gas storage container that stores the gas compressed by the gas compression device, and the storage An internal combustion engine comprising: a storage gas supply passage for connecting a gas container and an intake system passage through a flow passage switching device; an EGR valve provided in the EGR passage; and a control device for controlling the flow passage switching device. The amount of the gas accumulated in the intake passage from the intake manifold and from the intake manifold to the flow path switching device from the temperature and pressure of the gas inside the intake manifold. Calculating the amount of gas supplied to the cylinder by subtracting the amount accumulated in the passage from the amount of gas released from the gas storage container via the flow path switching device, When the excess air ratio is calculated from the supply amount and the fuel supply amount, and the calculated excess air ratio falls below the preset end limit excess air ratio, the supercharging assistance elapsed time is preset. Even before the end time elapses, the supercharging assistance using the gas from the gas storage container is controlled to end.

  According to this configuration, the supply amount of the accumulated gas supplied into the cylinder during the transient state is accurately grasped, and the supercharging assist stop condition is an air relationship between the air amount and the fuel supply amount. Since it can set with an excess rate, the supercharging assistance method in the supercharging assistance by the pressure-accumulated gas from the gas storage container can be optimized.

  In the above-described internal combustion engine, the control device starts when an excess air ratio calculated from an intake air amount, an EGR amount, and a fuel supply amount measured by an intake air amount sensor disposed in the intake passage is preset. When it is configured to control to start supercharging assistance using the gas from the gas storage container when the limit excess ratio is reached, the supercharging assistance start condition is set between the air amount and the fuel supply amount. Since it can set with the excess air ratio which is a relationship, the supercharging assistance method in the supercharging assistance by the pressure-accumulated gas from a gas storage container can be optimized.

  According to the supercharging assist method and the internal combustion engine of the internal combustion engine according to the present invention, a part of the exhaust gas, air, and any one of these mixed gases are stored in the gas storage container using the gas compression device, and the load In an internal combustion engine that temporarily suppresses the discharge of NOx in a transient state and improves acceleration performance in a transient state in which the gas suddenly increases, the accumulated gas from the gas storage container When the air is supplied to the intake passage, the accumulated amount of gas accumulated in the intake manifold and the like from the temperature and pressure of the gas inside the intake manifold is also measured from time to time along with the amount of accumulated gas released. Calculate and subtract the accumulated amount in the passage from the amount of gas supplied from the gas storage container, calculate the amount of gas supplied into the cylinder, and use the accumulated gas in the gas storage container. The accurately determined to supercharging assisting the end timing of the auxiliary can be controlled efficiently.

It is a figure showing composition of an internal-combustion engine of a 1st embodiment concerning the present invention. It is a figure which shows the structure of the internal combustion engine of 2nd Embodiment which concerns on this invention. FIG. 2 is a partially enlarged view of FIG. 1 showing a configuration in which a flow path switching device is mounted immediately before an intake manifold. It is a figure which shows an example of the flow of the supercharging assistance method of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows the detail of step S30 of FIG. It is a figure for demonstrating the drive of the gas compressor for stored gas. It is a figure which shows the structure of the flow-path switching apparatus comprised with the three-way switching valve in the state by which the intake line was connected. It is a figure which shows the structure of the flow-path switching apparatus comprised with the three-way switching valve in the state by which the stored gas supply line was connected. It is a figure which shows the structure of the internal combustion engine of a high pressure EGR system of a prior art. It is a figure which shows the structure of the low pressure EGR type internal combustion engine of a prior art. It is a figure which shows the relationship between the change of a vehicle speed, and instantaneous NOx discharge | emission amount. It is a figure which shows the characteristic of the fuel injection quantity in a full load, and the movement at the time of transition. It is a figure which shows the response delay of the turbo supercharger at the time of transition, and the relationship of EGR. It is a figure which shows the structure of the internal combustion engine of a prior art.

  Hereinafter, an internal combustion engine supercharging assist method and an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, an engine (internal combustion engine) 1 according to a first embodiment of the present invention includes an intake passage 12 connected to an engine body 11, an intake manifold 11a, and an exhaust passage 13 connected to an exhaust manifold 11b. It is configured. The intake manifold 11a and the intake passage 12 form an intake system passage, and the exhaust manifold 11b and the exhaust passage 13 form an exhaust system passage.

  The intake passage 12 is provided with a compressor 14a of a turbocharger 14, and the exhaust passage 13 is provided with a turbine 14b of a turbocharger 14, a diesel particulate filter (DPF) device 15, and a NOx occlusion reduction type. A NOx purification catalyst 16 formed of a catalyst or the like is provided.

  Further, an EGR passage 17 is branched from the exhaust passage 13 on the upstream side of the turbine 14b, and merges with the intake passage 12 on the downstream side of the compressor 14a at the EGR merging portion 18. The EGR passage 17 is provided with a diesel particulate filter (DPF) device 19, an EGR cooler 20, and an EGR valve 21 from the upstream side.

  Further, an exhaust gas introduction passage 22 is provided so as to branch from the exhaust passage 13 on the downstream side of the NOx purification catalyst 16. The exhaust gas introduction passage 22 is provided with an EGR cooler 23 and a three-way valve 24, and the exhaust gas introduction passage 22 is formed by a mechanical positive displacement turbocharger (preferably a reciprocating type) or the like. It is connected to the. The gas compression device 25 is connected to a gas storage container 27 formed of a pressure container or the like by a compressed gas supply passage 26. The gas storage container 27 is connected to the intake passage 12 by a stored gas supply passage 28. The exhaust gas introduction passage 22, the compressed gas supply passage 26 and the stored gas supply passage 28 form a pressure accumulation gas system passage.

  As shown in FIG. 6, the gas compression device 25 transmits power from an axle 31 of a vehicle on which the engine 1 is mounted to a drive shaft of the gas compression device 25 via gears 32 and 33 and an electromagnetic clutch 34. When the electromagnetic clutch 34 is turned on and connected, the gas compressor 25 is driven, and part of the exhaust gas G Gp from the exhaust gas introduction passage 22, the air Aa, and any one of these mixed gases C Is compressed and pressurized to be supplied to the gas storage container 27 and stored. A pressure regulating valve 29 is disposed in the stored gas supply passage 28 to adjust the pressure of the gas C supplied to the flow path switching device 30. At this time, the three-way valve 24 preferably adjusts the amount of part Gp of the exhaust gas G and the amount of air Aa to keep the oxygen concentration in the gas C stored in the gas storage container 27 substantially constant. Thus, the control when performing EGR can be simplified.

  In order to control the above devices, a control device 40 called an engine control unit (ECU) that controls the overall operation of the engine 1 is provided, and the control device 40 controls the pressure Pt in the gas storage container 27. The engine rotation speed Ne, the accelerator opening degree Ac, and the like are detected, and the electromagnetic clutch 34 and the three-way valve 24 are controlled based on the results, and the amount (pressure) of the gas C in the gas storage container 27 and the exhaust gas Gp The mixing ratio of air Aa is adjusted and controlled.

  As shown in FIG. 1, when the gas storage device 27 is provided with an adjustment valve 27a for adjusting the maximum pressure inside the gas storage container 27 and the gas compression device 25 is driven, work always occurs. The adjustment valve 27a is adjusted as follows. In FIG. 1, the adjustment valve 27 a is provided in the gas storage container 27, but the adjustment valve 27 a may be provided in the compressed gas supply passage 26 between the gas storage container 27 and the gas compression device 25.

  That is, the engine 1 has an EGR passage 17 for recirculating a part Ge of the exhaust gas G into the cylinder, a part Gp of the exhaust gas G of the engine 1, the air Aa, and any one of these mixed gases. A gas compression device 25 that compresses C, a gas storage container 27 that stores the gas C compressed by the gas compression device 25, and a gas storage supply passage 28 that connects the gas storage container 27 and the intake passage 12 are provided. Composed.

  The intake passage 12 and the stored gas supply passage 28 are connected via a flow path switching device 30. As shown in FIG. 1, the flow path switching device 30 is arranged on the downstream side of the EGR merging portion 18, which is a merging portion of the EGR passage 17 and the intake passage 12, and as shown in FIG. Provided immediately before. The flow switching device 30 is configured to switch between the stored gas supply passage 28 side and the upstream passage side of the intake passage 12 while the downstream passage side of the intake passage 12 is open. The flow path switching device 30 can be constituted by a three-way switching valve as shown in FIGS.

  In the flow path switching device 30 shown in FIGS. 7 and 8, the shutter 30c is moved by moving the rod 30b of the high-speed driving cylinder 30a by inserting the driving gas Ap and extracting the air Ae behind the piston. 7, the storage gas supply passage 28 side is closed as shown in FIG. 7, the upstream side 12a and the downstream side 12b of the intake passage 12 are communicated, and the upstream side of the intake passage 12 is connected as shown in FIG. The side 12a side is closed, and the stored gas supply passage 28 and the downstream side 12b of the intake passage 12 are communicated.

  In the present invention, as shown in FIG. 3, in order to measure the temperature Tm and the pressure Pm of the gas C inside the intake manifold 11a, a temperature sensor 41 and a pressure sensor 42 are arranged on the intake manifold 11a. As shown in FIGS. 7 and 8, the flow rate switching device 30 is provided with a flow rate measuring unit 43 for measuring the flow rate of the gas C from the storage gas container 27.

  The flow rate measurement unit 43 includes a Laval nozzle 43a for flow rate measurement, a first pressure measurement pipe 43b for measuring the pressure PH on the inlet side of the Laval nozzle 43a, and a sensor (not shown), and the Laval nozzle 43a. A second pressure measuring tube 43c and its sensor (not shown) for measuring the pressure PL of the narrowest part are arranged. Further, an intake air amount sensor 44 is provided in the upstream intake passage 12a, and a temperature sensor 45 for measuring the temperature of the gas C is provided in the stored gas supply passage 28, respectively. The outputs of these sensors 41 to 45 etc. are input to the control device 40.

  In the control device 40, when the gas C accumulated from the gas storage container 27 is supplied, the flow rate Wt of the gas C is measured every moment by the flow rate measurement unit 34, and the gas C inside the intake manifold 11a is measured. The temperature Tm and the pressure Pm are measured by the temperature sensor 41 and the pressure sensor 42 and accumulated in the intake manifold 11a and the passage from the flow path switching device 30 to the intake manifold 11a (hereinafter referred to as “intake manifold side passage”). The amount of gas C accumulated in the passage Wm is calculated, the amount of gas C supplied into the cylinder We and the amount of gas C released from the gas storage container 27 are grasped, and the gas in the gas storage container 27 is obtained. The supercharging assistance using C is accurately controlled.

  The supply amount We of the gas C supplied into the cylinder is obtained by subtracting the accumulated amount Wm of the gas C accumulated in the intake manifold side passage from the measured release amount Wt of the gas C (We = Wt− Wm). Further, the intake air amount when the supercharging assistance is not performed is measured by the intake air amount sensor 44. The oxygen concentration of the intake air can be calculated from the fuel injection amount Qin and the like by calculating the EGR rate from the valve opening degree of the EGR valve 21 and the like.

  Next, an engine (internal combustion engine) 1A according to a second embodiment of the present invention will be described. As shown in FIG. 2, in the engine 1A of the second embodiment, the EGR passage 17 is branched from the exhaust passage 13 on the downstream side of the NOx purification catalyst 16, and the EGR passage 17 is turbocharged. This is different from the first embodiment branched from the exhaust passage 13 on the upstream side of the turbine 14 b of the machine 14. Other points are the same as in the first embodiment.

  That is, the exhaust gas Ge flowing into the EGR passage 17 is a part of the exhaust gas G before passing through the turbine 14b of the turbocharger 14 in the engine 1 of the first embodiment. On the other hand, in the engine 1A of the second embodiment, it becomes a part of the exhaust gas G after passing through the turbine 14b of the turbocharger 14. In other words, the engine 1 of the first embodiment employs the high pressure EGR method, and the engine 1A of the second embodiment employs the low pressure EGR method.

  Next, a supercharging assist method for the internal combustion engine performed by the control device 40 of the engine (internal combustion engine) 1 or 1A will be described. This supercharging assist method for an internal combustion engine is a method that can be implemented by the engine 1 or 1A having the above-described configuration. In this supercharging assist method for an internal combustion engine, a part of the exhaust gas G in the exhaust passage (exhaust system passage) 13 of the engines 1 and 1A, the air Aa, and any one of these mixed gases C are compressed and stored. To do.

  At the same time, in the supercharging assistance method, when the operating state of the engine 1, 1A is not a transient state, a part Ge of the exhaust gas G of the engine 1, 1A is recirculated into the cylinder via the EGR passage 17, When the engines 1 and 1A are in a transient state, supercharging assistance for temporarily supplying the gas C to the intake passage (intake system passage) 12 is performed. That is, when the engines 1 and 1A are in a transient state, the EGR gas Ge from the EGR passage 17 and the fresh air A from the intake passage 12 are blocked by the flow path switching device 30, and only the gas C is passed through the EGR passage. 17 and the EGR merging portion 18, which is a merging portion between the intake passage 12 and the intake passage 12, is supplied downstream.

  Further, in this supercharging assist method for an internal combustion engine, a flow path switching device 30 configured by a three-way switching valve as shown in FIGS. 7 and 8 for shutting off the EGR gas Ge and fresh air A and supplying the gas C. To do.

  In these controls, the control device 40 detects detected values such as the engine speed Ne, the engine air amount (Mo, Me), the engine fuel amount (fuel injection amount) Q, the pressure Pt of the gas C inside the gas storage container 27, and the like. Based on these, the pressure regulating valve 29, the EGR valve 21, and the flow path switching device 30 are controlled.

  In this supercharging assist method, when the gas C accumulated from the gas storage container 27 is supplied, the discharge amount Wt of the gas C is measured every moment, and the temperature Tm of the gas C inside the intake manifold 11a is measured. The pressure Pm is measured, and the accumulation amount Wm of the gas C accumulated in the volume V in the intake manifold side passage (= volume Va of the intake manifold 11a + passage volume Vb from the flow path switching device 30 to the intake manifold 11a). Is calculated, the supply amount We of the gas C supplied into the cylinder and the discharge amount Wt of the gas C supplied from the storage gas container 27 are grasped, and the supercharging using the gas C stored in the storage gas container 27 is performed. Accurately control the assistance.

  The supply amount We of the gas C supplied into the cylinder is obtained by subtracting the accumulated amount Wm of the gas C accumulated in the intake manifold side passage from the measured release amount Wt of the gas C (We = Wt The calculation of the supply amount We of the gas C supplied into the cylinder will be described with reference to the control flow shown in FIG.

  The control flow of FIG. 4 is called and executed from the upper control flow when it is determined that it is necessary to calculate the supply amount We of the gas C supplied into the cylinder. It is shown as returning to the flow.

  When the control flow of FIG. 4 is called from the upper control flow and starts, the first group of data is input in step S11. As the input data of the first group, the temperature Tt of the gas C released from the gas storage container 27, the pressure PH of the first pressure measuring pipe 43b, the second measured by the flow rate measuring unit 43 provided with the Laval nozzle 43a. There is a pressure PL of the pressure measuring tube 43c.

  In the next step S12, from the data Tt, PH, and PL input in step S11, the calculation formula corresponding to the shape of the Laval nozzle 43a is used to calculate the amount of gas C passing through the Laval nozzle 43a, that is, from the gas storage container 27. A discharge amount Wt of the released gas C is calculated.

  In the next step S13, data of the second group is input. The input data of the second group includes the temperature Tm of the gas C inside the intake manifold 11a and the pressure Pm of the gas C measured by the temperature sensor 41 and the pressure sensor 42 provided in the intake manifold 11a. In the next step S14, the accumulation amount Wm of the gas C accumulated in the intake manifold side passage is calculated using the data Tm, Pm input in step S13 and the volume Vp in the intake manifold side passage. .

  In the next step S15, the accumulated amount Wm of the gas C accumulated in the intake manifold side passage is subtracted from the accumulated amount Ct of discharge of the gas C to obtain the supply amount We of the gas C supplied into the cylinder. And return.

  Next, the supercharging assistance method will be described with reference to the control flow shown in FIG. The control flow shown in FIG. 5 is called from the upper control flow along with the start of operation of the engines 1 and 1A. The control flow starts and repeats steps S21 to S27. It is shown that it occurs, goes to return from the middle of the flow, returns to the upper control flow, and stops the execution of this control flow.

  When the control flow of FIG. 5 starts, in step S21, the operation in the state where the normal intake passage 12 is in communication is performed for a predetermined time (preliminary setting relating to the determination interval of the excess air ratio λc in step S22). Time). Further, the intake air amount MAFc is measured by an intake air amount sensor (MAF sensor) 44 provided in the intake passage 12 of the normal line, and the fuel supply amount Qin into the cylinders of the engines 1 and 1A is measured. The excess air ratio λc is calculated from these measured values MAFc and Qin.

  In step S22, it is determined whether or not the calculated excess air ratio λc is equal to or less than a start limit excess air ratio λ1 that is a determination value for starting supercharging assistance. In this determination, if the excess air ratio λc is larger than the start limit excess air ratio λ1 (λc> λ1) (NO), the process returns to step S21, and if the start limit excess air ratio λ1 or less (λc ≦ λ1). (YES), go to step S23. This start limit excess air ratio λ1 is set by experiment.

  In step S23, the flow path switching device 30 is switched as shown in FIG. 8, the intake passage 12 is shut off, the stored gas supply passage 28 is communicated with the downstream side of the intake passage 12, and the stored gas container 27 is accumulated. Supercharging assistance using gas C is started. At the same time, a timer for measuring the supercharging assistance elapsed time Ti is started.

  In the next step S24, the “control flow for calculating the gas supply amount into the cylinder” in FIG. 4 is called to calculate the gas C supply amount We into the cylinder. Further, the fuel supply amount Qin introduced into the cylinders of the engines 1 and 1A is measured, and the excess air ratio λc is calculated.

  In the next step S25, it is determined whether or not the calculated excess air ratio λc is smaller than an end limit excess air ratio λ2, which is a determination value for stopping supercharging assistance. When the excess air ratio λc calculated in this determination is equal to or greater than the end limit excess air ratio λ2 (λc ≧ λ2) (NO), the process goes to step S26, and the supercharging assistance elapsed time Ti has passed the supercharging assistance set time Ts. If it has not elapsed (Ti <Ts) (NO), it is determined that the supercharging assistance is continued and the process returns to step S24. If it has elapsed (Ti ≧ Ts) (YES), the supercharging assistance is stopped and the process goes to step S27.

  If the excess air ratio λc is smaller than the end limit excess air ratio λ2 (λc <λ2) (YES) in step S25, the process goes to step S27. In this step S27, the supercharging assistance is stopped, the timer of the supercharging assistance elapsed time Ti is reset (Ti = 0), the process returns to step S21, and the upstream side and the downstream side of the intake passage 12 communicate with each other to store the gas. The engines 1 and 1A are operated in a normal line state where the supply passage 28 is blocked.

  When steps S21 to S27 are repeatedly performed and the engine 1, 1A is shut down, an interrupt is generated, the process returns, the control flow returns to the upper control flow, and the control flow of FIG. To do.

  According to the supercharging assist method and the engine (internal combustion engine) 1 and 1A, the turbocharger is used during transient operation of the engine 1 and 1A such as when the vehicle equipped with the engine 1 and 1A is suddenly accelerated or started. The reduction in acceleration performance due to the turbo lag of the turbocharger 14 can be prevented to a minimum, and the excess of gas C that can reduce particulate matter (PM) and nitrogen oxides (NOx) in the exhaust gas G In the charging assistance, the supercharging assistance stop condition and the supercharging assistance start condition can be set by the excess air ratio λc which is the relationship between the supply amount We of the gas C and the fuel supply amount Qin. The supercharging assistance method in the supercharging assistance by the accumulated gas C from the container 27 can be optimized.

  That is, the supply amount We of the gas C supplied into the cylinders of the engines 1 and 1A can be calculated to accurately estimate the total amount of the exhaust gas G and the discharge amounts of NOx, HC, CO, and the like whose discharge is restricted. . In addition, the fuel supply amount Qin supplied into the cylinder can be optimally controlled to keep the excess air ratio λc at a constant value.

  When supplying the stored gas C from the gas storage container 27 to the intake passage 12, the intake air W12 is inhaled from the temperature Tm and the pressure Pm of the gas C inside the intake manifold 11a together with the discharge amount Wt of the gas C every moment. The accumulation amount Wm of the gas C accumulated in the manifold side passage is calculated, and the accumulation of the gas C accumulated in the intake manifold side passage from the discharge amount Wt of the gas C supplied from the storage gas container 27 is calculated. By subtracting the amount Wm, the supply amount We of the gas C supplied into the cylinder is calculated, and the supercharging assistance using the pressure-accumulated gas C in the gas storage container 27 is accurately determined and supercharging is performed. Assistance can be controlled efficiently.

  A supercharging assist method and an internal combustion engine of an internal combustion engine according to the present invention use a gas compression device to store a part of exhaust gas, air, and any one of these mixed gases in a gas storage container, and the load is rapidly increased. In an internal combustion engine that temporarily suppresses the emission of NOx in a transient state and improves acceleration performance in a transient state that increases, supercharging using the gas accumulated in the gas storage container The supercharging assistance can be efficiently controlled by accurately determining the end time of the assistance.

  Therefore, using a gas compressor, a part of the exhaust gas, air, and any one of these mixed gases are stored in the gas storage container, and the gas is put into the cylinder in a transient state where the load increases rapidly. The present invention is applicable to a supercharging assist method for an internal combustion engine mounted on a truck, a bus, a passenger car, etc. and an internal combustion engine, which are temporarily supplied to suppress the emission of transient NOx and improve acceleration performance.

1, 1A, 1X, 1Y, 1Z engine (internal combustion engine)
11 Engine body 11a Intake manifold (intake system passage)
12 Intake passage (intake system passage)
13 Exhaust passage (exhaust system passage)
14 turbocharger 17 EGR passage 21 EGR valve 22 exhaust gas introduction passage 25 gas compression device 26 compressed gas supply passage 27 gas storage container 28 gas storage supply passage 30 flow passage switching device 40 control device 41 temperature provided in the intake manifold Sensor 42 Pressure sensor 43 provided in the intake manifold Flow rate measurement unit 43a Laval nozzle 43b First pressure measurement tube 43c Second pressure measurement tube 44 Intake amount sensor (MAF sensor)
45 Temperature sensor A provided in the storage gas supply passage Fresh air Aa Air C Gas G Exhaust gas Ge EGR gas Gp Exhaust gas part MAFC Intake amount PH Pressure of the first pressure measurement pipe Pressure PL of the second pressure measurement pipe Intake Pm Gas pressure Qin inside the manifold Qin Fuel supply amount Qt Supply target fuel amount Ti Supercharging assistance duration Tm Gas temperature inside the intake manifold Ts Supercharging assistance set time Tt Gas temperature Wt released from the gas storage container Gas flow rate Wm from the gas storage container Amount of gas accumulated in the intake manifold, etc. We Amount of gas supplied into the cylinder V A volume V on the intake manifold side
λc excess air ratio λ1 start limit excess air ratio λ2 end limit excess air ratio

Claims (4)

An EGR passage for recirculating a portion of the exhaust gas of the internal combustion engine into the cylinder;
A gas compression device for compressing a part of the exhaust gas of the internal combustion engine, air, and any of these mixed gases;
A gas storage container for storing the gas compressed by the gas compression device;
In the supercharging assist method for an internal combustion engine provided with a stored gas supply passage for connecting the gas storage container and the intake system passage through a flow switching device,
From the temperature and pressure of the gas inside the intake manifold, calculate the accumulated amount of the gas accumulated in the intake system passage from the intake manifold and the intake manifold to the flow path switching device,
From the amount of gas released from the gas storage container via the flow path switching device, subtract the accumulated amount in the passage to calculate the supply amount of the gas supplied into the cylinder,
The excess air ratio is calculated from the supply amount and the fuel supply amount,
When the calculated excess air ratio becomes equal to or less than a preset end limit excess air ratio, the gas storage container is provided even before the supercharging assistance elapsed time has passed the preset end time. A supercharging assistance method for an internal combustion engine, characterized in that the supercharging assistance using the gas from is terminated.   When the excess air ratio calculated from the intake air amount measured by the intake air amount sensor disposed in the intake passage, the EGR amount, and the fuel supply amount becomes equal to or less than a preset start limit excess rate, The supercharging assistance method for an internal combustion engine according to claim 1, wherein supercharging assistance using the gas from the gas storage container is started. An EGR passage for recirculating a portion of the exhaust gas of the internal combustion engine into the cylinder;
A gas compression device for compressing a part of the exhaust gas of the internal combustion engine, air, and any of these mixed gases;
A gas storage container for storing the gas compressed by the gas compression device;
A storage gas supply passage connecting the gas storage container and the intake system passage through a flow switching device;
In an internal combustion engine including an EGR valve provided in the EGR passage and a control device for controlling the flow path switching device,
The control device is
From the temperature and pressure of the gas inside the intake manifold, calculate the accumulated amount of the gas accumulated in the intake system passage from the intake manifold and the intake manifold to the flow path switching device,
From the amount of gas released from the gas storage container via the flow path switching device, subtract the accumulated amount in the passage to calculate the supply amount of the gas supplied into the cylinder,
The excess air ratio is calculated from the supply amount and the fuel supply amount,
When the calculated excess air ratio becomes equal to or less than a preset end limit excess air ratio, the gas storage container is provided even before the supercharging assistance elapsed time has passed the preset end time. An internal combustion engine that performs control to end supercharging assistance using the gas from the engine. The control device is
When the excess air ratio calculated from the intake air amount measured by the intake air amount sensor disposed in the intake passage, the EGR amount, and the fuel supply amount becomes equal to or less than a preset start limit excess rate, 4. The internal combustion engine according to claim 3, wherein control for starting supercharging assistance using the gas from the gas storage container is started.

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