JP2012251490A - Gas accumulation method for internal combustion engine and the internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas accumulation method for an internal combustion engine capable of maintaining an oxygen concentration of compressed gas in an accumulated gas container within a proper concentration range by accurately measuring the oxygen concentration of the gas stored in the accumulated gas container and suppressing variation in exhaust gas performance by supplying gas with a proper oxygen concentration stored in the accumulated gas container when performing supercharge-assist in a cylinder of an engine from the accumulated gas container, in the internal combustion engine using the compressed gas accumulated in the accumulated gas container for the supercharge-assist, and to provide the internal combustion engine.SOLUTION: In the control for adjusting an oxygen concentration Co in an accumulated gas container 27, a part Cp of gas C in the accumulated gas container 27 is led to a state closer to the atmospheric pressure in the measurement of the oxygen concentration Co of the gas C compressed in the accumulated gas container 27, and the oxygen concentration Coa of the gas Cp led to the state closer to the atmospheric pressure is measured. The measured value Coa is used as the measurement value Com of the oxygen concentration Co in the accumulated gas container 27.

Description

  The present invention relates to a gas storage 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 when the internal combustion engine is in a transient state.

  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. 11, 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. In the low pressure EGR system, for example, as shown in FIG. 12, 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 turbo-type supercharger 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. 13, 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. 14 and 15, 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. 16 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, when the composition of the pressure-accumulated gas in the gas storage container is adjusted based on the mixture ratio of the exhaust gas and air, even if the mixture ratio can be controlled to be constant, The oxygen concentration may change depending on the operating state of the engine, and the oxygen concentration of the gas cannot always be kept constant.

  In particular, when exhaust gas to be introduced into the gas storage container is introduced from the exhaust passage, there are cases where the oxygen concentration in the exhaust gas is low or the oxygen concentration is high depending on the load state of the engine. Therefore, when the gas in the gas storage container is controlled at a constant mixing ratio of exhaust gas and air, the oxygen concentration of the gas varies, so that there may be variations in exhaust performance of soot and NOx.

  In order to prevent this, it is considered effective to control the mixing ratio between the exhaust gas and air by measuring the oxygen concentration inside the gas storage container in order to suppress the variation in the exhaust performance. It is conceivable to use an oxygen concentration meter to measure the oxygen concentration inside this gas storage container, but the oxygen concentration meter is highly pressure dependent and it is necessary to correct the influence of the pressure in the gas storage container. There is a problem that the measurement accuracy is poor.

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. Stored in a gas storage container in an internal combustion engine that suppresses the emission of transient NOx and improves acceleration performance by temporarily supplying the gas into the cylinder during a transient state in which the load suddenly increases Accurately measure the oxygen concentration of the gas, maintain the oxygen concentration of the gas in the storage container within the appropriate concentration range, and when supercharging assistance from the storage container to the engine cylinder, It is an object of the present invention to provide a gas storage method for an internal combustion engine and an internal combustion engine that can suppress variations in exhaust gas performance by supplying a gas having an appropriate oxygen concentration stored in the engine.

  In order to achieve the above object, an internal combustion engine gas storage method according to the present invention includes an EGR passage for recirculating a part of exhaust gas of an internal combustion engine into a cylinder, a part of exhaust gas of the internal combustion engine, and air. And a gas compression device for compressing any one of these mixed gases, a gas storage container for storing the gas compressed by the gas compression device, and supplying the gas from the gas storage container to the intake system passage In the supercharging assist method for an internal combustion engine provided with a storage gas supply passage for controlling the oxygen concentration of the gas in the storage gas container, in the measurement of the oxygen concentration of the gas in the storage gas container, A part of the gas in the gas storage container is guided to a state close to atmospheric pressure, the oxygen concentration of the gas guided to a state close to atmospheric pressure is measured, and this measured value is stored in the gas storage container. Oxygen as measured value of gas oxygen concentration A method which comprises using a time measuring method.

  According to this method, in order to measure the oxygen concentration of the gas in the gas storage container with an oxygen concentration meter that is greatly affected by the pressure at the time of measurement, a part of the pressure-accumulated gas in the gas storage container to be measured is Then, after returning to the inlet side of the gas compression device for pressurizing the gas or opening it to the atmosphere and reducing the pressure to approximately atmospheric pressure, the oxygen concentration of the gas is measured with an oximeter. Thereby, the pressure dependence of the oxygen concentration meter can be eliminated, and the oxygen concentration of the gas in the gas storage container can be accurately measured.

  Therefore, it is possible to accurately measure the oxygen concentration of the gas stored in the gas storage container, maintain the oxygen concentration of the gas in the gas storage container within an appropriate concentration range, and supercharge assist from the gas storage container into the engine cylinder. When performing the above, it is possible to supply the gas having an appropriate oxygen concentration stored in the gas storage container, and to suppress variations in the exhaust gas performance.

  In the gas storage method for an internal combustion engine, when the pressure of the gas in the gas storage container is higher than a preset first upper limit pressure, the gas is released and exhaust gas or air is stored. When accumulating pressure in the gas container, the oxygen concentration of the gas in the gas storage container is measured in advance by measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measuring method. When the oxygen concentration is lower than the oxygen concentration, air is stored, and when the oxygen concentration of the gas in the storage gas container is higher than a preset first upper limit oxygen concentration, when the exhaust gas is stored, the oxygen concentration of the gas in the storage gas container The pressure can be efficiently maintained at an oxygen concentration within a preset range and a pressure within a preset range.

  Alternatively, in the gas storage method for an internal combustion engine, when the pressure of the gas in the gas storage container is higher than a first upper limit pressure set in advance, the gas is released and exhaust gas or air is stored. When accumulating pressure in the gas container, the oxygen concentration of the gas in the gas storage container is measured in advance by measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measuring method. When the pressure is lower than the oxygen concentration and the pressure of the gas in the gas storage container is equal to or lower than a preset second upper limit pressure lower than the first upper limit pressure, the air is stored without releasing the gas. And when the oxygen concentration of the gas in the gas storage container is lower than a preset second lower limit oxygen concentration lower than the first lower limit oxygen concentration, and the pressure of the gas in the gas storage container is the first Than the upper limit pressure When the gas pressure is larger than the preset second upper limit pressure, the gas is discharged to accumulate air, and when the oxygen concentration of the gas in the gas storage container is higher than the preset first upper limit oxygen concentration, and When the pressure of the gas in the gas storage container is equal to or lower than a preset second upper limit pressure lower than the first upper limit pressure, the exhaust gas is stored without releasing the gas, and the gas storage container When the oxygen concentration of the gas is higher than a preset second upper limit oxygen concentration higher than the first upper limit oxygen concentration and the pressure of the gas in the gas storage container is higher than the second upper limit pressure, When the exhaust gas is accumulated by releasing the gas, the oxygen concentration and pressure of the gas in the gas storage container can be efficiently maintained at the oxygen concentration within the preset range and the pressure within the preset range.

  An internal combustion engine for achieving the above object is an internal combustion engine capable of implementing the gas storage 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 for compressing a part of the exhaust gas of the internal combustion engine, air, and a mixed gas thereof, a gas storage container for storing the gas compressed by the gas compression device, and the gas storage gas An internal combustion engine comprising: a storage gas supply passage for supplying the gas from a container to an intake system passage; and a control device for controlling a device for accumulating exhaust gas or air in the storage gas container. In the control for adjusting the oxygen concentration of the gas in the gas storage container, a state in which a part of the gas in the gas storage container is close to atmospheric pressure by measuring the oxygen concentration of the gas in the gas storage container Lead to It is configured to perform control using an oxygen concentration measurement method that measures the oxygen concentration of the gas led to a state close to atmospheric pressure and uses the measured value as a measured value of the oxygen concentration of the gas in the gas storage container. The According to this configuration, in order to measure the oxygen concentration of the gas in the gas storage container with the oxygen concentration meter that is greatly affected by the pressure at the time of measurement, a part of the pressure-accumulated gas in the gas storage container is measured. Then, after returning to the inlet side of the gas compression device for pressurizing the gas or opening it to the atmosphere and reducing the pressure to approximately atmospheric pressure, the oxygen concentration of the gas is measured with an oximeter. Thereby, the pressure dependence of the oxygen concentration meter can be eliminated, and the oxygen concentration of the gas in the gas storage container can be accurately measured.

  Therefore, it is possible to accurately measure the oxygen concentration of the gas stored in the gas storage container, maintain the oxygen concentration of the gas in the gas storage container within an appropriate concentration range, and supercharge assist from the gas storage container into the engine cylinder. When performing the above, it is possible to supply the gas having an appropriate oxygen concentration stored in the gas storage container, and to suppress variations in the exhaust gas performance.

  In the internal combustion engine, when the pressure of the gas in the gas storage container is higher than a preset first upper limit pressure, the control device releases the gas and converts the exhaust gas or air into the gas storage gas. When accumulating pressure in the container, the first lower limit oxygen in which the oxygen concentration of the gas in the gas storage container is set in advance while measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measuring method. When the concentration is lower than the concentration, air is stored, and when the oxygen concentration of the gas in the storage gas container is higher than a preset first upper limit oxygen concentration, control is performed to store the exhaust gas. With this configuration, the oxygen concentration and pressure of the accumulated gas in the gas storage container can be efficiently maintained at the oxygen concentration within the preset range and the pressure within the preset range.

  Alternatively, in the internal combustion engine, when the pressure of the gas in the gas storage container is higher than a preset first upper limit pressure, the control device releases the gas and supplies the exhaust gas or air to the When accumulating pressure in the gas storage container, the oxygen concentration of the gas in the gas storage container is set in advance while the oxygen concentration of the gas in the gas storage container is measured by the oxygen concentration measuring method. When the oxygen concentration is lower than the lower limit oxygen concentration and the pressure of the gas in the gas storage container is equal to or lower than a preset second upper limit pressure lower than the first upper limit pressure, the air is discharged without releasing the gas. And when the oxygen concentration of the gas in the gas storage container is lower than a preset second lower limit oxygen concentration lower than the first lower limit oxygen concentration, and the pressure of the gas in the gas storage container is the first 1 Upper limit pressure Is less than a preset second upper limit pressure, when the gas is discharged to accumulate air, and when the oxygen concentration of the gas in the gas storage container is higher than a preset first upper limit oxygen concentration, And when the pressure of the gas in the gas storage container is equal to or lower than a preset second upper limit pressure lower than the first upper limit pressure, the exhaust gas is stored without releasing the gas, and the gas storage container When the oxygen concentration of the gas in the gas is higher than a preset second upper limit oxygen concentration higher than the first upper limit oxygen concentration and the pressure of the gas in the gas storage container is higher than the second upper limit pressure, Control is performed to release the gas and accumulate the exhaust gas. With this configuration, the oxygen concentration and pressure of the accumulated gas in the gas storage container can be efficiently maintained at the oxygen concentration within a predetermined range and the pressure within the predetermined range.

  According to the internal combustion engine gas storage method and internal combustion engine according to the present invention, the gas compression device is used to store a part of the exhaust gas, air, and any one of these mixed gases in the gas storage container, and the load is increased. In an internal combustion engine that temporarily suppresses NOx emission in a transient state and improves acceleration performance in a transient state that increases rapidly, oxygen in the gas stored in the gas storage container Concentration can be measured accurately, the oxygen concentration of the accumulated gas in the gas storage container can be maintained in the appropriate concentration range, and when supercharging assistance is performed from the gas storage container to the engine cylinder, Variations in exhaust gas performance can be suppressed by supplying gas.

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 the structure relevant to the oxygen concentration measurement in a gas storage container. It is a figure which shows the other structure relevant to the oxygen concentration measurement in a gas storage container. It is a figure which shows an example of the control flow of the gas storage method of 1st Embodiment which concerns on this invention. It is a figure which shows an example of the control flow of the gas storage method of 2nd Embodiment which concerns on this invention. It is a figure which shows an example of the control flow of the control method intertwined with the gas storage method and the supercharging assistance method. 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 gas storage 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 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. 8, 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 Pm 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 the air Aa is adjusted and controlled.

  As shown in FIG. 3, an electromagnetic on-off valve 27 a that adjusts the maximum pressure inside the gas storage container 27 is provided in the gas storage container 27. Further, in order to measure the oxygen concentration of the gas C inside the gas storage container 27, an oxygen concentration measurement passage 51 that communicates with the gas storage container 27 is provided. An electromagnetic on-off valve 52 and an oxygen concentration meter 53 are provided from the gas storage container 27 side. The oxygen concentration measurement passage 51 is configured to communicate with the exhaust gas introduction passage 22 upstream of the gas compression device 25 so that the gas C after the oxygen concentration is measured is returned to the inlet side of the gas compression device 25. Alternatively, as shown in FIG. 4, the gas C after measuring the oxygen concentration may be configured to be released into the atmosphere as being open to the atmosphere. The gas storage container 27 is provided with a thermometer 54 and a pressure gauge 55 for measuring the temperature of the gas C inside the gas storage container 27.

  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. 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 addition, although not shown, the intake valve provided in the intake system passage 12 and the opening / closing valve provided in the stored gas supply passage 28 may be used. That is, in the case of a system in which the intake passage 12 is closed with an intake valve (intake throttle) or the like without using the flow path switching device 30, an EGR merging portion 18 is provided upstream of the intake valve (not shown), and EGR Gas Ge is shut off in two stages by an EGR valve 21 and an intake valve (not shown).

  In the flow path switching device 30 shown in FIGS. 9 and 10, the shutter gas 30p is moved by moving the rod 30b of the cylinder 30a for high speed driving by inserting the driving gas Ap and extracting the air Ae on the back surface of the piston. 9, the stored gas supply passage 28 side is closed, and the upstream side 12a and the downstream side 12b of the intake passage 12 are communicated with each other, and as shown in FIG. The upstream side 12 a side is closed, and the stored gas supply passage 28 and the downstream side 12 b of the intake passage 12 are communicated.

  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 branches from the exhaust passage 13 downstream of the NOx purification catalyst 16, and the exhaust gas introduction passage 22 branches from the EGR passage 17. The EGR passage 17 branches from the exhaust passage 13 upstream of the turbine 14 b of the turbocharger 14, and the exhaust gas introduction passage 22 branches from the exhaust passage 13 downstream of the NOx purification catalyst 15. This is different from the first embodiment. 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 gas storage 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 internal combustion engine gas storage method is a method that can be implemented by the engine 1 or 1A having the above-described configuration. First, a supercharging assistance method for an internal combustion engine will be described. 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 engine 1, 1A is compressed and stored by compressing the air Aa and any one of these mixed gases C. To do.

At the same time, in the supercharging assist method, when the engine 1, 1A is not in a transient operation, a part Ge of the exhaust gas G of the engine 1, 1A is recirculated into the cylinder via the EGR passage 17, and the engine 1, 1A is recirculated. During the transient operation of 1A, the gas C accumulated from the gas storage container 27 is temporarily supplied to the intake passage (intake system passage) 12. That is, when the operating state of the engines 1 and 1A is in a transient state, the EGR gas Ge from the EGR passage 17 and the fresh air A from the intake passage 12 are shut off by the flow path switching device 30, and only the gas C is discharged. Supply to the intake passage 12.

  Further, in this supercharging assist method for the internal combustion engine, the flow path switching device 30 configured by a three-way switching valve as shown in FIGS. 9 and 10 for shutting off the EGR gas Ge and fresh air A and supplying the gas C. Or the EGR gas Ge and the fresh air A are shut off and the gas C is supplied to an intake valve (not shown) provided in the intake passage (intake system passage) 12 and to the stored gas supply passage 28. Open / close valve (not shown).

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

  Next, the gas storage method for the internal combustion engine of the first embodiment will be described based on the flowchart illustrated in FIG. The gas storage method for the internal combustion engine of the first embodiment is performed by the control device 40 according to a control flow as exemplified in FIG. The control flow of FIG. 5 is called from the upper control flow together with the start of operation of the engines 1 and 1A and starts, and steps S11 to S12, or steps S11 to S15, or steps S11 to S17 are performed. Repeatedly, an interruption is generated by stopping the operation of the engines 1 and 1A, the return is performed from the middle of the flow, the control flow is returned to the upper control flow, and the execution of this control flow is stopped.

  When the control flow of FIG. 5 is called, whether or not the measured pressure Pm, which is the pressure of the gas C inside the storage gas container 27 measured by the pressure gauge 55, is higher than the preset first upper limit pressure P1 in step S11. Determine. If the measured pressure Pm is higher than the first upper limit pressure P1 (Pm> P1) (YES), the electromagnetic on / off valve 27a is closed in advance while the electromagnetic on / off valve 52 is closed in step S12. Meanwhile, the valve C is opened to release the gas C, and the pressure of the gas C in the gas storage container 27 is lowered so that the exhaust gas G or the air Aa can be further stored in the gas storage container 27. The value of this release time Tdb is set by experiment. When the measurement pressure Pm is equal to or lower than the first upper limit pressure P1 (Pm ≦ P1) (NO), a part Gp of the air Aa or the exhaust gas G is stored in the gas storage container 27 in steps S13 to S17.

  In step S13, the oxygen concentration Co of the gas C inside the gas storage container 27 is measured. In the oxygen concentration measurement method for measuring the oxygen concentration Co of the gas C in the gas storage container 27, a part Cp of the gas C in the gas storage container 27 is led to a state close to atmospheric pressure, and close to atmospheric pressure. The oxygen concentration Coa of the gas Cp led to the state is measured. This measured value Coa is defined as a measured value Com of the oxygen concentration Co of the gas C in the gas storage container 27.

  That is, with the electromagnetic on / off valve 27a closed, the electromagnetic on / off valve 52 of the oxygen concentration measurement passage 51 of the gas storage container 27 is opened for a preset open time Tda, and the gas C in the gas storage container 27 is opened. A part of Cp is introduced into the upstream side of the inlet side of the gas compression device 25 (configuration shown in FIG. 3) or opened to the atmosphere (configuration shown in FIG. 4) to open the gas C in the gas storage container 27 to be measured. The partial Cp is set to be substantially atmospheric pressure, the oxygen concentration Co of the partial Cp of the gas C that has become substantially atmospheric pressure is measured by the oxygen concentration meter 53, and this measured value Coa is measured as oxygen of the gas C in the gas storage container 27. The measured value Com of the concentration Co is assumed to be. The value of the opening time Tda is determined in consideration of the responsiveness of the oximeter 53 in an experiment, but it is preferable to set the time as short as possible.

  In the next step S14, it is determined whether or not the oxygen concentration Com is lower than a preset first lower limit oxygen concentration Cb1 (lower limit determination). If it is determined in step S14 that the oxygen concentration Com is equal to or higher than the first lower limit oxygen concentration Cb1 (Com ≧ Cb1) (NO), the process goes to step S16, where the oxygen concentration Com is lower than the first lower limit oxygen concentration Cb1 (Com In the case of <Cb1) (YES), go to step S15 and accumulate air Aa.

  In the accumulation of air Aa in step S15, the three-way valve 24 is switched so that the air Aa side and the gas compression device 25 side communicate with each other, and the gas compression device 25 is driven to accumulate the air Aa for a preset supply time Tse. Supply to the gas container 27. The value of the supply time Tse is set by an experiment or the like. Then, it returns to step S11.

  In step S16, it is determined whether or not the oxygen concentration Com is higher than a preset first upper limit oxygen concentration Cc1. If it is determined in step S16 that the oxygen concentration Com is higher than the first upper limit oxygen concentration Cc1 (Com> Cc1) (YES), the process goes to step S17 to accumulate the exhaust gas G, and the oxygen concentration Com is the first. If the upper limit oxygen concentration is less than or equal to Cc1 (Com ≦ Cc1) (NO), the process directly returns to step S11.

  In the accumulated pressure of the exhaust gas G in step S17, strictly speaking, in the accumulated pressure of a part Gp of the exhaust gas G, the three-way valve 24 is switched so that the part Gp side of the exhaust gas G and the gas compression device 25 side communicate with each other. The compressor 25 is driven to supply a part Gp of the exhaust gas G to the gas storage container 27 for a preset supply time Tse. Then, it returns to step S11.

  By repeating Step S11 to Step S17, the oxygen concentration Co of the gas C in the gas storage container 27 is maintained within a target range (Cb1 ≦ Co ≦ Cc1). Then, an interruption occurs due to the stop of the operation of the engines 1 and 1A, a return is made from the middle of the flow, the control flow is returned to the upper control flow, and this control flow is stopped together with the stop of the upper control flow.

  Next, a gas storage method for an internal combustion engine according to a second embodiment will be described based on a flowchart illustrated in FIG. The gas storage method for the internal combustion engine of the second embodiment is performed by the control device 40 according to a control flow as exemplified in FIG. The control flow of FIG. 6 is called from the upper control flow together with the start of operation of the engines 1 and 1A, and starts. Steps S21 to S22, or steps S21 to S28, or steps S21 to S30 are performed. Repeatedly, an interruption is generated by stopping the operation of the engines 1 and 1A, the return is performed from the middle of the flow, the control flow is returned to the upper control flow, and the execution of this control flow is stopped.

  When the control flow of FIG. 6 is called, in step S21, the gas C inside the gas storage container 27 measured by the pressure gauge 55 is measured as in step S11 of FIG. 5 of the gas storage method of the first embodiment. It is determined whether or not the measured pressure Pm, which is a pressure, is higher than a preset first upper limit pressure P1. When the measured pressure Pm is higher than the first upper limit pressure P1 (Pm> P1) (YES), the electromagnetic on / off valve 27a is set to the preset release time Tdb while the electromagnetic on / off valve 52 is closed in step S22. Meanwhile, the valve C is opened to release the gas C, and the pressure of the gas C in the gas storage container 27 is lowered so that the exhaust gas G or the air Aa can be further stored in the gas storage container 27. The value of this release time Tdb is set by experiment. When the measurement pressure Pm is equal to or lower than the first upper limit pressure P1 (Pm ≦ P1) (NO), the air Aa or the exhaust gas G is accumulated in the gas storage container 27 in steps S23 to S30.

  In step S23, the oxygen concentration Co of the gas C stored in the gas storage container 27 is measured. The oxygen concentration measurement method for measuring the oxygen concentration Co of the gas C in the gas storage container 27 is the same as the oxygen concentration measurement method of the first embodiment, and is the same as step S13.

  In the next step S24, a first determination is made. In the first determination, when the oxygen concentration Com of the gas C in the gas storage container 27 is lower than the first lower limit oxygen concentration Cb1 set in advance, and the pressure Pm of the gas C in the gas storage container 27 is set in advance. It is determined whether or not the preset second upper limit pressure P2 is lower than the first upper limit pressure P1. When the oxygen concentration Com is lower than the first lower limit oxygen concentration Cd1 (Com ≧ Cb1) and the pressure Pm is equal to or lower than the second upper limit pressure P2 (Pm ≦ P2) (YES), the gas storage container 27 is filled. Assuming that there is room for storing gas, the air Aa is stored in step S28 without releasing the gas C. The pressure accumulation of the air Aa in step S28 is the same as step S15 of the gas storage method of the first embodiment. If not (NO), go to step S25.

  In step S25, a second determination is made. In this second determination, when the oxygen concentration Com of the gas C in the gas storage container 27 is lower than the preset second lower limit oxygen concentration Cb2 lower than the first lower limit oxygen concentration Cb1, and the gas in the gas storage container 27 It is determined whether the pressure Pm of C is larger than a preset second upper limit pressure P2 that is lower than the first upper limit pressure P1. When the oxygen concentration Com is lower than the second lower limit oxygen concentration Cb2 (Com <Cb2) and the pressure Pm is higher than the second upper limit pressure P2 (Pm> P2) (YES), the gas storage container 27 stores gas. In step S29, the electromagnetic on-off valve 27a is opened for a preset release time Tdb, and the accumulated gas C is released in step S29. Go to S28 and accumulate air Aa. If not (NO), go to step S26.

  In step S26, a third determination is made. In the third determination, when the oxygen concentration Com of the gas C in the gas storage container 27 is higher than the preset first upper limit oxygen concentration Cc1, and the pressure Pm of the gas C in the gas storage container 27 is the first. It is determined whether or not it is equal to or lower than a preset second upper limit pressure P2 lower than the upper limit pressure P1. When the oxygen concentration Com is higher than the first upper limit oxygen concentration Cc1 and the pressure Pm is equal to or lower than the second upper limit pressure P2, it is assumed that there is room for storing gas in the gas storage container 27, and the accumulated gas C Without exhausting the exhaust gas G, the exhaust gas G is accumulated in step S30. The pressure accumulation of the exhaust gas G in step S30 is the same as step S17 of the gas storage method of the first embodiment. If not (NO), go to step S27.

  In step S27, a fourth determination is made. In the fourth determination, the oxygen concentration Com of the gas C in the gas storage container 27 is higher than a preset second upper limit oxygen concentration Cc2 higher than the first upper limit oxygen concentration Cc1, and the gas C in the gas storage container 27 It is determined whether or not the pressure Pm is higher than the second upper limit pressure P2. If the oxygen concentration Com is higher than the second upper limit oxygen concentration Cc2 and the pressure Pm is higher than the second upper limit pressure P2 (YES), it is determined that there is no room for storing gas in the gas storage container 27, and in step S31, electromagnetic With the on-off valve 52 closed, the electromagnetic on-off valve 27a is opened for a preset release time Tdb to release the accumulated gas C, and then the process goes to step S30 to accumulate the exhaust gas G. Otherwise (NO), the process returns to step S21.

  By repeating Step S21 to Step S22, Step S21 to Step S28, or Step S21 to Step S30, the oxygen concentration Co of the gas C in the gas storage container 27 is within a target range (Cb1 ≦ Co ≦ Cc1). Then, an interruption occurs due to the stop of the operation of the engines 1 and 1A, a return is made from the middle of the flow, the control flow is returned to the upper control flow, and this control flow is stopped together with the stop of the upper control flow.

  Next, control involving the gas storage method and the supercharging assist method for the internal combustion engine according to the first and second embodiments will be described with reference to a flowchart illustrated in FIG. This control relates to the relationship between the supercharging assistance that supplies the gas C stored in the cylinders of the engines 1 and 1A from the gas storage container 27 (supercharging assistance) and the stored gas.

  This control is performed by the control device 40 according to a control flow as exemplified in FIG. The control flow in FIG. 7 is called from the upper control flow when the operation of the engine 1 or 1A starts, starts, and repeats step S41 to step S43 or step S41 to step S44 to execute the engine 1, 1A. An interruption is generated by stopping the operation, and a return is made from the middle of the flow to return to a higher control flow, and execution of this control flow is stopped.

  If the control flow of FIG. 7 is called, it will be determined whether supercharging assistance was implemented by step S41. When supercharging assistance is not performed (NO), the state of the gas C stored in the gas storage container 27 is determined in the next step S42. In this determination, the oxygen concentration Com of the gas C in the gas storage container 27 falls within the target oxygen concentration range (Cd1 ≦ Com ≦ Cc1), that is, ΔC with respect to the target set concentration Ct. (Cd1 = Ct−ΔC, Cc1 = Ct + ΔC), and at the same time, whether the internal pressure Pm of the gas C in the gas storage container 27 is within the range of ΔP with respect to the target set pressure Pt. Determine whether. This ΔC is determined from the sensitivity of the engine performance to the oxygen concentration, and ΔP is, for example, the internal pressure Pm of the gas C in the gas storage container 27 and the auxiliary equipment after the duration of supercharging assistance (for example, 1 second) has elapsed. Determined from the minimum pressure required to move the class.

  If it is determined in step S42 that the oxygen concentration and pressure of the gas C are within the set range (YES), the process goes to step S43, and the control for storing gas is not performed for a predetermined time (supercharging assistance in step S41). Elapses for a period of time related to the determination interval). If either the oxygen concentration Com or the pressure Pm of the gas C is not within the set range, the process goes to step S44 to perform control for storing gas. As control for this gas storage, the control of FIG. 5 or the control of FIG. 6 can be used.

  If supercharging assistance is performed in the determination of step S41 (YES), the stored gas C in the storage gas container 27 is supplied into the cylinders of the engines 1 and 1A, and then the process goes to step S44. Control for gas storage.

  This step S41 to step S43 or step S41 to step S44 is repeatedly performed, and an interruption occurs due to the operation stop of the engine 1 or 1A. The process returns to the middle of the flow, returns to the upper control flow, and returns to the upper control flow. This control flow is also stopped when the control flow is stopped. With the control in FIG. 7, it is possible to determine whether or not supercharging assistance using the accumulated gas C is performed, and whether or not to perform control for storing gas.

  According to the gas storage method for the internal combustion engine and the engines (internal combustion engines) 1 and 1A, the oxygen concentration Co of the gas C in the gas storage container 27 is measured by the oxygen concentration meter 53 that is greatly influenced by the pressure at the time of measurement. In order to do this, after returning a part Cp of the gas C in the gas storage container 27 to be measured to the inlet side of the gas compression device 25 or opening it to the atmosphere and reducing the pressure to approximately atmospheric pressure, The oxygen concentration meter 53 measures the oxygen concentration Coa of the gas Cp. Thereby, the pressure dependence of the oxygen concentration meter 53 can be eliminated, and the oxygen concentration Co of the gas C in the gas storage container 27 can be accurately measured.

  Therefore, the oxygen concentration Co of the gas C stored in the gas storage container 27 can be accurately measured, and the oxygen concentration Co of the gas C in the gas storage container 27 can be maintained within an appropriate concentration range. When supercharging assistance is performed in the cylinders of 1 and 1A, the gas C having an appropriate oxygen concentration Co stored in the gas storage container 27 can be supplied to suppress variations in exhaust gas performance.

  Further, the oxygen concentration Co and the pressure Pm of the stored gas C in the gas storage container 27 can be efficiently maintained at the oxygen concentration within a preset range and the pressure within the preset range.

  The internal combustion engine and the internal combustion engine according to the present invention are the internal combustion engine that performs supercharging assistance using the stored gas, accurately measures the oxygen concentration of the gas stored in the storage gas container, and the gas in the storage gas container The oxygen concentration can be maintained within the appropriate concentration range, and when supercharging assistance is performed from the gas storage container into the engine cylinder, the gas with the appropriate oxygen concentration stored in the gas storage container is supplied and exhausted. Because variation in gas performance can be suppressed, a part of the exhaust gas, air, and one of these mixed gases are stored in the gas storage container, and the accumulated gas during the transient operation where the load increases rapidly is stored in the cylinder. It can be used in a gas storage method for an internal combustion engine mounted on a truck, a bus, a passenger car, etc., and an internal combustion engine that can be temporarily supplied to suppress NOx emission during transient operation and improve acceleration performance.

1, 1A, 1X, 1Y, 1Z engine (internal combustion engine)
11 Engine body 11a Intake manifold (intake system passage)
11b Exhaust manifold (exhaust 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 27a Electromagnetic on-off valve 28 Gas storage supply passage 30 Channel switching device 31 Vehicle axle 34 Electromagnetic Clutch 35 Intake valve (intake throttle)
40 Control Device 51 Oxygen Concentration Measuring Path 52 Electromagnetic On-Off Valve 53 Oxygen Concentrator 54 Thermometer 55 Pressure Gauge A Fresh Air Aa Air Ac Accelerator Opening C Gas Cb1 First Lower Limit Oxygen Concentration Cb2 Second Lower Limit Oxygen Concentration Cc1 First Upper Limit Oxygen Concentration Cc2 Second upper limit oxygen concentration Co Gas oxygen concentration Coa Oxygen concentration of gas led to a state close to atmospheric pressure Com Measured value of oxygen concentration in gas storage container Cp Part of gas in gas storage container Ct Target set oxygen Concentration G Exhaust gas Ge EGR gas Gp Exhaust gas part Ne Engine rotation speed P Intake pressure P1 First upper limit pressure P2 Second upper limit pressure Pm Internal pressure (measurement pressure) of gas storage container
Pt Set pressure Tda Release time Tdb Release time Tse Supply time

Claims (6)

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 assistance method for an internal combustion engine comprising a storage gas supply passage for supplying the gas from the gas storage container to the intake system passage,
In the control for adjusting the oxygen concentration of the gas in the gas storage container, by measuring the oxygen concentration of the gas in the gas storage container, a part of the gas in the gas storage container is brought into a state close to atmospheric pressure. An oxygen concentration measurement method is used in which the oxygen concentration of the gas led to a state close to atmospheric pressure is measured, and the measured value is used as a measurement value of the oxygen concentration of the gas in the gas storage container. A gas storage method for an internal combustion engine. When the pressure of the gas in the gas storage container becomes higher than a preset first upper limit pressure, the gas is released,
When accumulating exhaust gas or air in the gas storage container, while measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measurement method,
When the oxygen concentration of the gas in the gas storage container is lower than a preset first lower limit oxygen concentration, air is stored,
2. The gas storage method for an internal combustion engine according to claim 1, wherein when the oxygen concentration of the gas in the gas storage container is higher than a preset first upper limit oxygen concentration, the exhaust gas is stored. When the pressure of the gas in the gas storage container becomes higher than a preset first upper limit pressure, the gas is released,
When accumulating exhaust gas or air in the gas storage container, while measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measurement method,
When the oxygen concentration of the gas in the gas storage container is lower than a preset first lower limit oxygen concentration, and the pressure of the gas in the gas storage container is lower than a preset first upper limit pressure. When the pressure is below the second upper limit pressure, air is accumulated without releasing the gas,
When the oxygen concentration of the gas in the gas storage container is lower than a preset second lower limit oxygen concentration lower than the first lower limit oxygen concentration, and the pressure of the gas in the gas storage container is higher than the first upper limit pressure. Less than the preset second upper limit pressure, the gas is released to accumulate air,
When the oxygen concentration of the gas in the gas storage container is higher than a preset first upper limit oxygen concentration, the gas pressure in the gas storage container is lower than the first upper limit pressure. When the pressure is below 2 upper limit pressure, the exhaust gas is accumulated without releasing the gas,
The oxygen concentration of the gas in the gas storage container is higher than a preset second upper limit oxygen concentration higher than the first upper limit oxygen concentration, and the pressure of the gas in the gas storage container is higher than the second upper limit pressure. 2. The gas storage method for an internal combustion engine according to claim 1, wherein when the temperature is high, the gas is discharged and the exhaust gas is stored. 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 stored gas supply passage for supplying the gas from the gas storage container to the intake system passage;
In an internal combustion engine comprising a control device for controlling a device for accumulating exhaust gas or air in the gas storage container,
In the control in which the control device adjusts the oxygen concentration of the gas in the storage gas container, a part of the gas in the storage gas container is increased by measuring the oxygen concentration of the gas in the storage gas container The oxygen concentration of the gas led to a state close to atmospheric pressure and the state close to atmospheric pressure is measured with an oxygen concentration meter, and this measurement value is used as a measurement value of the oxygen concentration of the gas in the gas storage container. An internal combustion engine characterized by performing control using an oxygen concentration measurement method. When the pressure of the gas in the gas storage container is higher than a preset first upper limit pressure, the control device releases the gas,
When accumulating exhaust gas or air in the gas storage container, while measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measurement method,
When the oxygen concentration of the gas in the gas storage container is lower than a preset first lower limit oxygen concentration, air is stored,
5. The internal combustion engine according to claim 4, wherein when the oxygen concentration of the gas in the gas storage container is higher than a preset first upper limit oxygen concentration, control for accumulating exhaust gas is performed. The control device is
When the pressure of the gas in the gas storage container becomes higher than a preset first upper limit pressure, the gas is released,
When accumulating exhaust gas or air in the gas storage container, while measuring the oxygen concentration of the gas in the gas storage container by the oxygen concentration measurement method,
When the oxygen concentration of the gas in the gas storage container is lower than a preset first lower limit oxygen concentration, and the gas pressure in the gas storage container is lower than the first upper limit pressure. When the pressure is below 2 upper limit pressure, the air is stored without releasing the gas, and the oxygen concentration of the gas in the gas storage container is lower than a preset second lower limit oxygen concentration lower than the first lower limit oxygen concentration. And when the pressure of the gas in the gas storage container is higher than a preset second upper limit pressure lower than the first upper limit pressure, the gas is discharged to accumulate air,
When the oxygen concentration of the gas in the gas storage container is higher than a preset first upper limit oxygen concentration, the gas pressure in the gas storage container is lower than the first upper limit pressure. When the pressure is below 2 upper limit pressure, the exhaust gas is accumulated without releasing the gas,
The oxygen concentration of the gas in the gas storage container is higher than a preset second upper limit oxygen concentration higher than the first upper limit oxygen concentration, and the pressure of the gas in the gas storage container is higher than the second upper limit pressure. 5. The internal combustion engine according to claim 4, wherein when it is high, control is performed to release the gas and accumulate the exhaust gas.

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