JP5834504B2 - Supercharging assist method for internal combustion engine and internal combustion engine - Google Patents

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 a pressure-accumulated gas accumulated 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.

  On the other hand, in recent years, when the output of an internal combustion engine is increased, a so-called downsizing movement in which the internal combustion engine of a vehicle is replaced with an internal combustion engine with a small displacement and a high output from a conventional internal combustion engine with a small displacement. Has become a big flow. However, in this downsized vehicle, the startability deteriorates with the small displacement internal combustion engine, so this gas storage supply system is an extremely effective means.

  However, this storage gas supply system is effective for improving startability and reducing fuel consumption. However, when accelerating for overtaking from a steady driving state, for example, the oncoming vehicle prevents the danger of a collision urgently. Therefore, there is a problem that it becomes difficult to control supercharging assistance when acceleration is required more rapidly than at high speed.

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 the transient state and improves acceleration performance by temporarily supplying the accumulated gas into the cylinder during a transient state in which the load increases rapidly, the control device In addition to the supercharging assistance using the accumulated pressure gas that is automatically determined and determined, it is possible to perform supercharging assistance by manual operation, and it is possible to perform sufficient supercharging assistance even during sudden acceleration such as overtaking acceleration An object of the present invention is to provide a supercharging assist method for an internal combustion engine and an internal combustion engine.

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 a turbocharger, when it is determined that the operation state of the internal combustion engine is in a transient state, supercharging is performed using the stored gas from the livestock gas container. While performing the auxiliary, even when the supercharging assistance start switch is turned on by manual operation, supercharging assistance is performed using the accumulated gas from the livestock gas container , and after the supercharging assistance operation is finished, The supercharging assist activation switch A method characterized by a switch to OFF.

  According to this method, in addition to the supercharging assistance using the stored pressure gas that is automatically performed by determining the transient state, the control device can perform supercharging assistance by manual operation. In this case, sufficient supercharging assistance can be performed.

  In the above-described supercharging assist method for an internal combustion engine, the accumulated pressure of a part of the exhaust gas is performed during the normal operation of the internal combustion engine, and the accumulated pressure of air is stored in the operation of the internal combustion engine. Adopting a method that is performed only when the vehicle is in a braking state, the air is charged into the gas storage container when the vehicle is in the braking state, so that the braking energy can be regenerated and the fuel can be improved. Can do.

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 In an internal combustion engine having a storage gas supply passage for connecting a gas container and an intake system passage through a flow passage switching device, an EGR valve, an intake valve, a control device for controlling the flow passage switching device, and manual supercharging assist activation Provided with a switch, and when the control device determines that the operating state of the internal combustion engine is in a transient state, the control device performs supercharging assistance using the pressure-accumulated gas from the gas storage container, and performs supercharging by manual operation. Auxiliary start switch is O Been even when, with a control for supercharging assisting with accumulator gas from the gas storage container, and the control device, after finishing the supercharging auxiliary operation, the supercharging auxiliary starting switch It is configured to control to turn off .

  According to this configuration, in addition to the supercharging assistance using the accumulated pressure gas that is automatically determined by determining the transient state, the supercharging assistance by the manual operation can be performed. Therefore, during sudden acceleration such as overtaking acceleration In this case, sufficient supercharging assistance can be performed.

  In the internal combustion engine described above, the control device stores a part of exhaust gas in the storage gas container during normal operation of the internal combustion engine, and stores air in the storage container during operation of the internal combustion engine. If the control is performed only when the state is the braking state, air is charged into the gas storage container at the time of the braking state, so that the braking energy can be regenerated and the fuel consumption can be improved. Can be improved.

  According to the supercharging assistance method and the internal combustion engine of the internal combustion engine according to the present invention, a part of the exhaust gas of the internal combustion engine, air, and any one of these mixed gases are stored in the gas storage container using the gas compression device. In an internal combustion engine that suppresses transient NOx emissions and improves acceleration performance by temporarily supplying accumulated pressure gas into the cylinder in a transient state where the load increases suddenly, the controller is in a transient state In addition to supercharging assistance that uses accumulated pressure gas that is automatically determined, supercharging assistance by manual operation can be performed, and sufficient supercharging assistance can be provided even during sudden acceleration such as overtaking acceleration it can.

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. It is a figure which shows an example of control of the supercharging assistance method of embodiment which concerns on this invention. It is a figure which shows the detail of gas storage control of step S20 of FIG. It is a figure which shows the detail of the supercharging assistance control of step S30 of FIG. It is a figure for demonstrating the drive of the gas compression apparatus 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.

  In the intake passage 12, an air mass flow sensor (MAF sensor) 52, an intake valve (intake throttle) 51, and a compressor 14 a of the turbocharger 14 are provided in order from the upstream side, and a turbo-type supercharger is provided in the exhaust passage 13. A turbine 14b of the machine 14, a diesel particulate filter (DPF) device 15, a NOx storage reduction catalyst 16 and the like are 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 upstream 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. At this time, it is preferable that the three-way valve 24 adjusts the amount of part Gp of the exhaust gas G and the amount of air Aa to keep the oxygen concentration in the stored gas C stored in the storage gas container 27 substantially constant, Thereby, the control when performing EGR can be simplified. As shown in FIG. 1, an electromagnetic valve 29 is arranged in the stored gas supply passage 28 to control the supply of the stored pressure gas C to the flow path switching device 30.

  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 disposed on the downstream side of the EGR merging portion 18 that is a merging portion of the EGR passage 17 and the intake passage 12. 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.

  A control device 40 called an engine control unit (ECU) is provided in order to perform overall operation of the engine 1 and control of the above-described devices. As shown in FIG. , The pressure P0 in the gas storage container 27, the engine rotational speed Ne, the accelerator opening α, etc. are detected, and the electromagnetic clutch 34 and the three-way valve 24 are controlled based on the results, The amount of the accumulated gas C (pressure P0) and the mixing ratio of the exhaust gas Gp and the air Aa are adjusted and controlled.

  Furthermore, when a manual supercharge assist start switch (not shown) is provided in the driver's seat of the vehicle equipped with the engine 1 and the driver determines that further supercharge assist is necessary, such as during sudden acceleration In addition, when the driver turns on the supercharging assistance start switch, the control device 40 is configured to perform supercharging assistance regardless of the determination of the transient state.

  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, 1A or the like 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 accumulated 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 accumulated gas C is taken into the intake passage. 12 is supplied.

  Further, in this supercharging assist method for an internal combustion engine, a flow path switching device constituted 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 accumulated gas C. 30.

  In these controls, the control device 40 is based on the detected value of the engine speed Ne, the engine air amount (Mo, Me), the engine fuel amount (fuel injection amount) Q, the pressure P0 inside the gas storage container 27, and the like. Thus, the electromagnetic valve 29, the EGR valve 21, and the flow path switching device 30 are controlled.

  Next, the supercharging assistance method in this invention is demonstrated. This supercharging assistance method is a control method in the engine 1 of the first embodiment and the engine 1A of the second embodiment, and is implemented by the control device 40.

  This supercharging assistance method is performed along a control flow as illustrated in FIG. In the control flow of FIG. 3, when the engine starts, the control flow of FIG. 3 is called from the upper control flow and starts. The stored gas pressure P0 in the gas storage container 27 is measured in the first step S11, and the stored gas pressure P0 is determined in the next step S12.

  In this determination, the stored gas pressure P0 is compared with the target gas pressure Pt. If the stored gas pressure P0 is lower than the target gas pressure Pt (P0 <Pt) (NO), the stored gas pressure P0 is set to the target gas pressure Pt. Therefore, it goes to the gas storage control in step S20, and a part Gp of the exhaust gas G or air Aa is filled. Further, in this determination, when the stored gas pressure P0 is equal to or higher than the target gas pressure Pt (P0 ≧ Pt) (YES), it is determined that the supercharging assistance condition by the accumulated gas C is satisfied, and the supercharging assistance in step S30 is performed. Go to control and perform supercharging assistance with the accumulated gas C.

  When Step S20 or Step S30 is completed, the process returns to Step S11, and Steps S11 to S20 or Steps S11 to S30 are repeated. When the engine is stopped, an interruption occurs and the process returns to the advanced control flow, and the advanced control flow ends. At the same time, the control flow of FIG.

  In the gas storage control in step S20, as shown in FIG. 4, a temporary target pressure (absolute pressure, the same applies hereinafter) Pme for filling a part Gp of the exhaust gas G is calculated in the first step S21. When the stored gas pressure (residual pressure in the container) P0 of the gas storage container 27 is the target gas pressure Pt (= P0 + ΔP), the provisional target pressure Pme is “P0 + Cgt × (Pt−P0) = P0 + (Pt−P0) × (Ptg). / Pt) ".

  That is, if the ratio of the exhaust gas Gp in the gas C supplied into the gas storage container 27 is Cg, the target partial pressure Ptg of the exhaust gas Gp is “Pt × Cgt”, and the partial pressure ΔPg for additional filling is “ΔP × Cgt ". Further, the target partial pressure Pta of the air Aa is “Pt × Cga = Pt × (1−Cgt)”, and the partial pressure ΔPa for the additional filling is “ΔP × (1−Cgt)”. Since the ratio “Cg / (1−Cg)” of the partial pressure ΔPg of the exhaust gas Gp and the partial pressure ΔPa of the air Aa does not change even when the stored gas pressure P0 changes, the provisional target pressure Pme is “P0 + Cgt × ΔP = P0 + Cgt × (Pt−P0) = P0 + (Pt−P0) × (Ptg / Pt) ”.

  Therefore, the exhaust gas Gp is charged until the stored gas pressure P0 reaches the provisional target pressure Pme, in other words, the exhaust gas Gp corresponding to Cgt × ΔP / Pt is additionally charged. After that, until the air Aa reaches Pt, in other words, the air Aa corresponding to (1−Cgt) × ΔP / Pt may be additionally charged.

  In the next step S22, the three-way valve 24 is switched so that a part Gp of the exhaust gas G is supplied to the gas compression device 25, the electromagnetic clutch 34 is turned on, and a preset time (the stored gas in step S23). During a period related to the pressure determination interval, the exhaust gas Gp is accumulated in the gas storage container 27.

  In the next step S23, it is determined whether or not the stored gas pressure P0 has reached the temporary target pressure Pme. If the stored gas pressure P0 has not reached the temporary target pressure Pme (P0 <Pme) (NO), the process proceeds to step S22. Returning, when the stored gas pressure P0 becomes the provisional target pressure Pme (PO ≧ Pme) (YES), the process goes to step S24, the electromagnetic clutch 34 is turned off, the pressure accumulation of the exhaust gas Gp is terminated, and the next step S25 is performed. go. That is, the exhaust gas Gp is stored until the stored gas pressure P0 reaches the temporary target pressure Pme.

  In the next step S25, it is determined whether or not the engine is in a braking state. If the engine is not in a braking state (NO), the electromagnetic clutch 34 is turned off in step S26 for a predetermined time. After the elapse of (time related to the engine operating state interval in step S25), the process returns to step S25. When the engine is not in the braking state, the gear ratio between the axle and the electromagnetic clutch between the axle and the gas compressor is a gear ratio for controlling the rotational speed of the gas compressor 25 during load operation. Control to the ratio.

  When the engine is in a braking state, it means that the engine is in a brake operating state, and means that any one of a foot brake, an exhaust brake, an engine brake, and other auxiliary brakes is in an operating state. To do. As the control, the rotational speed of the drive shaft 31 on the vehicle side is measured, and it is determined that the vehicle is in a braking state when the rate of decrease in the rotational speed is equal to or less than a preset rotational speed decrease rate. Alternatively, the operation of the foot brake, the exhaust brake, the engine brake, and other auxiliary brakes is monitored, and when any of them is in the operating state, it is determined that it is in the braking state.

  In step S25, when the engine operating state is in a braking state (YES), the process goes to step S27, and the speed ratio between the axle and the gas compressor between the axle and the electromagnetic clutch is set to the rotational speed of the gas compressor 25. Control is performed so as to achieve a preset rotational speed, the three-way valve 24 is switched so that the air Aa is supplied to the gas compression device 25, the electromagnetic clutch 34 is turned on, and a preset time (step) The air Aa is accumulated in the gas storage container 27 during the time related to the determination interval of the gas storage pressure in S28).

  That is, the pressure accumulation of air Aa is limited to when the engine operating state is in a braking state. Thereby, the filling of the air Aa is performed by regenerating braking energy, so that a fuel efficiency effect can be expected.

  In the next step S28, it is determined whether or not the stored gas pressure P0 has reached the final target pressure Pt. If the stored gas pressure P0 has not reached the final target pressure Pt (P0 <Pt) (NO), the process proceeds to step S25. Returning, when the stored gas pressure P0 reaches the final target pressure Pt (PO ≧ Pt) (YES), the process goes to step S29, the electromagnetic clutch 34 is turned off, and the stored pressure of the air Aa is terminated. That is, the air Aa is stored until the stored gas pressure P0 reaches the final target pressure Pt.

  In the supercharging assistance control in step S30, as shown in FIG. 5, it is determined in the first step S31 whether or not a manual supercharging assistance start switch for supercharging assistance is ON. If this manual supercharging assist start switch is ON (YES), the process goes to step S33 to forcibly assist supercharging using the accumulated gas C.

  If it is determined in step S31 that the manual supercharging assist start switch is not ON (NO), the process proceeds to step S32, and it is determined whether or not the engine operating state is a transient state such as at the time of start or sudden acceleration. This determination is made, for example, by reading the accelerator opening degree α and using the speed of the accelerator opening degree α, and a case where the accelerator depression speed (dα / dt) exceeds a preset set speed αvc is regarded as a transient state. judge.

  If it is determined in step S32 that the state is in a transient state (YES), the process goes to step S33 to forcibly assist supercharging using the accumulated gas C. If it is determined in step S32 that the state is not a transient state (NO), step S30 is terminated.

In step S33, supercharging assistance is performed for a preset time (for example, about 1 second), and thereafter supercharging assistance is stopped. In this supercharging assistance, the EGR valve 21 and the intake valve (intake throttle) 51 are fixed fully closed, and the electromagnetic valve 29 is fully opened. Further, the flow path switching device 30 is switched from the communication state of the intake line of FIG. 7 to the communication state of the stored gas supply line of FIG. The set time is a time for maintaining the supercharging assist state, and is set to an optimum value by experiment or the like, but about 1 second is sufficient.

  At this time, the control device 40 performs EGR control, measures the intake air amount (MAF) with the air mass flow sensor (MAF sensor) 52, and attempts to control the valve opening degree of the EGR valve 21 so as to reach the target intake air amount. To do. In this case, if the air mass flow sensor 52 is disposed upstream of the intake valve 51 as shown in FIGS. 1 and 2, the air mass flow sensor 52 measures the intake amount as zero because the intake valve 51 is fully closed. Therefore, since the operation amount of the EGR valve 21 is set to zero, the normal EGR control and the control in step S33 do not interfere with each other.

  On the other hand, when the air mass flow sensor 52 is arranged on the downstream side of the intake valve 51, the air mass flow sensor 52 measures the flow rate of the accumulated gas C from the flow path switching device 30 even when the intake valve 51 is fully closed. It will not be zero. Therefore, in normal EGR control, the EGR valve 21 is controlled to be opened. That is, normal EGR control interferes with the control in step S33. Therefore, priority is given to the operation of the EGR valve 21 and the intake valve 51 in the supercharging assistance in step S33 over the EGR control, and the EGR valve 21 and the intake valve 51 are fixed to be fully closed.

  Then, when the supercharging assistance in step S33 passes the set time, the supercharging assistance is canceled in step S34, the supercharging assistance operation is terminated, the closed closing of the EGR valve 21 and the intake valve 51 is released, Return to EGR control and intake control. Also, the manual supercharging assist start switch is turned off.

  That is, if the manual supercharge assist start switch is ON, it is switched to OFF, and if the manual supercharge assist start switch is OFF, it is left as it is. Step S30 is ended.

  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. By the pressure accumulation gas C which can prevent the fall of the acceleration performance resulting from the turbo lag of the turbocharger 14 to the minimum, and can reduce particulate matter (PM) and nitrogen oxides (NOx) in the exhaust gas G In the supercharging assistance, in addition to the supercharging assistance using the stored pressure gas C that is automatically performed by determining the transient state, the supercharging assistance can be performed by manual operation, and sudden acceleration such as during overtaking acceleration can be performed. Sufficient supercharging assistance can be performed even at times.

  Further, the pressure accumulation of a part Gp of the exhaust gas G in the gas storage container 27 is performed during the normal operation of the engine 1, 1A, and the pressure accumulation of the air Aa in the gas storage container 27 is determined in the operation state of the engine 1, 1A. If the method that is performed only when the vehicle is in the braking state is adopted, the air storage container 27 is charged with the air Aa when the vehicle is in the braking state, so that the braking energy can be regenerated and the fuel can be improved. Can do.

  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 supplies accumulated pressure gas into the cylinder during an increasing transient state to suppress NOx emission in the transient state and improve acceleration performance, the control device automatically determines the transient state and automatically In addition to supercharging assistance using the accumulated pressure gas to be performed, supercharging assistance by manual operation can be performed, and sufficient supercharging assistance can be performed even during sudden acceleration such as overtaking acceleration.

  Therefore, using a gas compression device, a part of the exhaust gas, air, and one of these mixed gases are stored in the gas storage container, and the accumulated gas is put into the cylinder in a transient state where the load increases rapidly. It can be used in a supercharging assistance method and an internal combustion engine for an internal combustion engine mounted on a truck, a bus, a passenger car, or the like, which is temporarily supplied to suppress transient NOx emission 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 Turbo-type supercharger 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 Channel switching device 40 Control device 51 Intake valve 52 Air mass flow sensor (MAF sensor)
A Fresh air Aa Air C Accumulated gas (gas)
Cg Exhaust gas ratio G Exhaust gas Ge EGR gas Gp Part of exhaust gas P0 Pressure in storage gas container Pme Temporary target pressure Pt Final target pressure Pta Target partial pressure of air Ptg Target partial pressure of exhaust gas ΔPa Additional filling of air Minute partial pressure ΔPg Partial pressure α of additional charge of exhaust gas Accelerator opening αvc Setting speed

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 one 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,
When it is determined that the operating state of the internal combustion engine is in a transient state, supercharging assistance is performed using the accumulated gas from the livestock gas container, and also when the supercharging assistance start switch is turned on manually. , Perform supercharging assistance using the accumulated gas from the livestock gas container ,
Further, after the supercharging assist operation is finished, the supercharging assist start switch is turned off, and the supercharging assist method for the internal combustion engine is characterized by.   Accumulation of a part of the exhaust gas in the gas storage container is performed during normal operation of the internal combustion engine, and pressure accumulation of air in the gas storage container is performed only when the operation state of the internal combustion engine is in a braking state. The supercharging assist method for an internal combustion engine according to claim 1. 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 one of these mixed gases;
A gas storage container for storing the gas compressed by the gas compression device;
In an internal combustion engine having a storage gas supply passage for connecting the gas storage container and an intake system passage through a flow switching device,
A control device for controlling the EGR valve, the intake valve, the flow path switching device, and a manual supercharging assist start switch;
The control device
When it is determined that the operating state of the internal combustion engine is in a transient state, supercharging assistance is performed using the stored pressure gas from the gas storage container, and also when the supercharging assistance start switch is turned on manually. , Control to perform supercharging assistance using the pressure accumulation gas from the gas storage container ,
Further, the control device performs control to turn off the supercharging assist start switch after finishing the supercharging assist operation .   The control device stores a part of exhaust gas in the gas storage container during normal operation of the internal combustion engine, and stores air pressure in the gas storage container when the internal combustion engine is in a braking state. 4. The internal combustion engine according to claim 3, wherein control is performed only at times.

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