JP5830946B2 - 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 gas stored in a gas storage container into a cylinder in a transient state of the internal combustion engine.

  In EGR (exhaust gas recirculation) for reducing NOx (nitrogen oxide) in exhaust gas of an internal combustion engine such as a diesel engine, there are a high pressure EGR method and a low pressure EGR method in an internal combustion engine equipped with a supercharging system. In this high pressure EGR system, for example, as shown in FIG. 17, in an internal combustion engine 1X having 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. 18, 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. 19, 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. 20 and 21, 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. 22 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.

  After starting this supercharging assistance, the gas accumulated in the intake manifold is supplied from the gas storage container, the intake manifold internal pressure (boost pressure) rises, and the engine is supercharged. The intake manifold internal pressure varies depending on the rise of the intake manifold internal pressure caused by the gas pumped from the gas storage container and the consumption rate of the gas in the intake manifold of the engine.

  And, it takes a certain amount of time before the gas is pumped from the gas storage container to the intake manifold, and the engine intake pressure is intermittently performed. Increases in the low speed range just before the start of supercharging assistance. That is, the maximum value of the cylinder internal pressure is generated immediately after the start of supercharging assistance, in other words, the engine rotational speed is in a low speed region.

  In the low speed range immediately after the start of this transient operation, the amount of fuel to be introduced is relatively small, and the internal pressure (boost pressure) of the intake manifold rises quickly due to supercharging assistance, so the excess air ratio is easily made relatively high. be able to. On the other hand, when the fuel amount in the latter half of the supercharging assistance shifts from the medium speed range to the high speed range where the fuel amount rapidly increases, the gas in the gas storage container is consumed, so the excess air ratio decreases. For this reason, the supply amount of gas to be supercharged is suppressed in the low speed range immediately after the start of supercharging assistance with a relatively large excess air ratio, and the supercharging assistance gas is to be increased in the middle speed range of the latter half of supercharging assistance. It is necessary to increase the supply amount.

  Taking this into account, the intake manifold internal pressure is measured, and the area of the gas outlet of the storage gas container is controlled based on this measured value. Control the supercharging pressure during supercharging assistance by limiting the amount of gas released to a small level and opening the area of the outlet above the medium speed range to increase the amount of gas released for supercharging assistance. The method to do is conceivable. However, this method has a problem that the control is complicated and the cost is increased.

  On the other hand, in the storage gas supply system, the present inventor, even if the pressure in the storage gas container before releasing the stored gas is constant, the storage after the gas release is performed depending on the volume of the storage gas container. The knowledge that the internal pressure of the gas container (the pressure of the gas stored inside the gas storage container) and the amount of gas released from the gas storage container change, and as a result, the maximum combustion pressure in the cylinder of the engine changes. Obtained.

  In other words, when the internal pressure of the gas storage container when the gas stored in the supercharging assistance is started to be constant, the gas is constant from the gas storage container when the volume of the gas storage container is small (for example, 40 liters). When the intake manifold is supplied with a volume, the internal pressure of the gas storage container decreases as the gas decreases, but the amount of decrease is larger when the volume is smaller than when the volume is larger (for example, 80 liters).

In relation to this, in FIGS. 8 to 13, the engine speed is changed from 1000 rpm to 2800 rpm in 2 seconds with the change of the fuel supply amount Qf (mm ³ / st), and gas is supplied from the storage gas container. The experimental result of the relationship between the volume of a gas storage container and various quantities at the time of performing supercharging assistance is shown.

FIG. 8 shows changes over time in the intake manifold internal pressure and the amount of gas released from the gas storage container when the gas storage container internal pressure is 4.8 kg / cm ² and the volume of the gas storage container is 40 liters. Further, FIG. 9 shows the change over time in the intake manifold internal pressure and the amount of gas released from the gas storage container when the pressure in the gas storage container is also 4.8 kg / cm ² and the volume of the gas storage container is 80 liters. Indicates. FIG. 10 shows the transition of the internal pressure of the gas storage container with a broken line for 40 liters and a thick line for 80 liters.

  In either case, as the internal pressure of the gas storage container decreases, the intake manifold internal pressure (boost pressure) also decreases. However, the smaller the volume of the gas storage container, the greater the amount of gas pressure decrease than the larger volume. The maximum value of the cylinder internal pressure of the engine in a transient operation state with supercharging assistance is smaller when the volume of the gas storage container is smaller than when the volume is larger.

  FIG. 11 shows NO. In the case where the volume of the gas storage container is 40 liters. 1-NO. 4 shows the transition of each cylinder internal pressure (combustion pressure), and FIG. 1-NO. 4 shows the transition of the internal pressure of each cylinder. FIG. 13 shows the transition of the excess air ratio for each cycle (every two engine revolutions), with a white circle (broken line) for 40 liters and a black circle (thick line) for 80 liters.

  In other words, when the volume of the gas storage container is small, the decrease in the internal pressure of the gas storage container after the start of supercharging assistance is large, so the gas supply amount decreases, and the volume is large after the middle speed after the middle period of supercharging assistance The excess air ratio is smaller than In order to increase the excess air ratio in the latter half of the supercharging assistance, the internal pressure of the gas storage container is set high if an attempt is made to extend the time during which the gas can be supplied while maintaining the pressure of the supercharging assistance gas at a predetermined pressure or higher. Or it is necessary to enlarge the volume of the gas storage container.

  However, in any of these cases, the maximum value Pmax of the cylinder internal pressure becomes large at the time of supercharging assistance. Therefore, this maximum value Pmax is the maximum allowable value of the cylinder internal pressure that is set to guarantee the durability of the engine. The problem arises that there is a possibility of exceeding.

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. Suppose that gas is supplied from a gas storage container in an internal combustion engine that suppresses NOx emission in the transient state and improves acceleration performance in a transient state where the load increases rapidly. When supercharging assistance is performed, immediately after this supercharging assistance starts, the pressure of the gas from the gas storage container can be lowered to suppress the maximum value of the cylinder internal pressure, and a sufficient amount of gas can be used in the second half of supercharging assistance. It is an object to provide a supercharging assist method for an internal combustion engine and an internal combustion engine capable of supplying a sufficient amount of air to the cylinder to ensure a sufficient excess air ratio.

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 supercharging assisting method for an internal combustion engine having a gas storage supply passage connecting through, so that the gas pressure supplied to the first chamber of the gas storage container becomes a predetermined first pressure, the gas storage vessel While adjusting the gas pressure supplied to the second chamber to a predetermined second pressure, the gas discharged from the gas compression device is supplied to the first chamber and the second chamber, Immediately after the start of feeding assistance, the first chamber is stored with the first pressure. The gas is supplied into the cylinder, and when the supply reduces the indoor pressure of the first chamber below a preset pressure value, the pressure accumulated in the second chamber at the second pressure is stored. The method is characterized in that gas is supplied to the first chamber and supercharging assistance is performed until the determination of completion of supercharging assistance is performed.

  According to this method, immediately after the start of supercharging assistance, supercharging assistance is performed in a state where the apparent volume of the gas storage container of only the first chamber where the indoor pressure is not so high, the maximum value of the cylinder internal pressure in the low speed range Pmax can be suppressed, and after the medium speed at which the chamber pressure in the first chamber decreases, the gas in the second chamber is supplied to the first chamber, so supercharging assistance can be performed with a sufficient amount of gas, It is possible to prevent a decrease in the excess air ratio during the second half of the supercharging assistance.

  That is, in the low speed range at the start of supercharging assistance, the maximum volume Pmax of the cylinder internal pressure can be suppressed by setting the apparent volume of the gas storage container small and setting the indoor pressure not so high. After the middle speed of the second half of the assistance, the amount of gas that can be supplied can be increased, the apparent volume of the gas storage container can be increased, and the excess air ratio by supercharging assistance can be increased.

  In the above-described supercharging assist method for an internal combustion engine, when the indoor pressure in the first chamber falls below a preset pressure value, a check provided in the communication path between the first chamber and the second chamber When the valve is opened by a differential pressure between the indoor pressure of the second chamber and the indoor pressure of the first chamber, and the gas accumulated in the second chamber is supplied to the first chamber, It is possible to automatically perform two-stage supercharging assistance with a relatively simple configuration in which a check valve is provided without requiring a control device or the like.

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 connecting a gas container and an intake system passage via a flow switching device, the storage container is formed of a plurality of chambers including at least a first chamber and a second chamber, A pressure accumulation gas supply passage for supplying the gas into the cylinder is connected to the first chamber, a first passage for supplying gas discharged from the gas compression device, and a gas discharged from the gas compression device The first passage A second passage for supplying the first chamber of the gas storage container, the gas discharged from the gas compression device, and a third passage for supplying from said first passage to the second chamber of the gas storage container, said first A first regulator that is provided in two passages and adjusts the gas pressure supplied to the first chamber to a predetermined first pressure; and is provided in the third passage and is supplied to the second chamber. A second regulator that adjusts the gas pressure to be a predetermined second pressure, and from the gas compressor with respect to the indoor pressure of the first chamber accumulated by the gas from the gas compressor. The pressure in the second chamber accumulated by the gas is configured to be separately settable, and the second chamber and the first chamber are communicated via a check valve, and the check valve is When the indoor pressure in the first chamber drops below a preset pressure value, the chamber in the second chamber Characterized by being configured to open by the differential pressure between the interior pressure of the pressure between the first chamber.

  According to this configuration, immediately after the start of supercharging assistance, supercharging assistance can be performed in a state where the apparent volume of the gas storage container of only the first chamber in which the room pressure is not so high is small, and the cylinder internal pressure in the low speed range can be obtained. The maximum value Pmax of the first storage chamber can be suppressed, and after the medium speed at which the chamber pressure in the first chamber decreases, the check valve automatically opens and the first chamber communicates with the second chamber. Supercharging assistance can be performed in a state where the volume is large, and a decrease in the excess air ratio during the latter half of the supercharging assistance can be prevented.

  In other words, in the low speed range at the start of supercharging assistance, the apparent volume of the gas storage container is made small, and the indoor pressure is set not to be too high, and the maximum value Pmax of the cylinder internal pressure is suppressed, and the latter half of the supercharging assistance. After the medium speed, the amount of gas that can be supplied can be increased, the apparent volume of the gas storage container can be increased, and the excess air ratio by supercharging assistance can be increased.

  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 accumulates and temporarily supplies the gas into the cylinder in a transient state where the load increases suddenly to suppress the discharge of NOx in the transient state and improve acceleration performance, the gas is supplied from the gas storage container. When supplying supercharging assistance, immediately after the start of supercharging assistance, the gas pressure from the gas storage container can be lowered to suppress the maximum value of the cylinder internal pressure, and in the latter half of supercharging assistance, a sufficient amount can be obtained. A sufficient excess air ratio can be secured by supplying gas into the cylinder.

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 of a gas storage container. In the gas storage container of FIG. 3, it is a figure which shows the state which is performing supercharging assistance only in the 1st chamber immediately after supercharging assistance start. In the gas storage container of FIG. 3, it is a figure which shows the state which the check valve of the latter half of supercharging assistance is connected, and is performing supercharging assistance in the 1st chamber and the 2nd chamber. In the two-stage supercharging assistance of “first chamber” and “first chamber + second chamber”, NO. 1-NO. FIG. 4 is a diagram showing a transition of the pressure in each cylinder. It is a figure which shows the time change of the excess air rate in the case of the two-stage supercharging assistance of "the 1st chamber" and "the 1st chamber + the 2nd chamber", and the case where the volume of the gas storage container is 40 liters and 80 liters. . It is a figure which shows the time change of the intake manifold internal pressure in case the volume of a gas storage container is 40 liters, and the gas amount discharge | released from a gas storage container. It is a figure which shows the time change of the intake manifold internal pressure in case the volume of a gas storage container is 80 liters, and the gas amount discharge | released from a gas storage container. It is a figure which shows transition of the gas storage container internal pressure in case the volume of a gas storage container is 40 liters and 80 liters. When the volume of the gas storage container is 40 liters, NO. 1-NO. FIG. 4 is a diagram showing a transition of the pressure in each cylinder. When the volume of the gas storage container is 80 liters, NO. 1-NO. FIG. 4 is a diagram showing a transition of the pressure in each cylinder. It is a figure which shows the time change of the excess air ratio in case the volume of a gas storage container is 40 liters and 80 liters. 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.

  The intake passage 12 is provided with an intake valve (intake throttle) 51 and a compressor 14a of a turbocharger 14, and the exhaust passage 13 is provided with a turbine 14b of a turbocharger 14 and a diesel particulate filter (DPF). ) A NOx purification catalyst 16 formed by the device 15 and a NOx occlusion reduction type 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. 14, 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.

  As shown in FIG. 3, the gas storage container 27 is formed by a plurality of chambers of a first chamber 27 a and a second chamber 27 b, and gas C is supplied to the first chamber 27 a into the cylinder of the engine 1. The stored gas supply passage 28 is connected, the compressed gas supply passage 26 from the gas compressor 25 is branched, and the first branch compressed gas supply passage 26a connected to the first chamber 27a and the second chamber 27b are connected. A bifurcated compressed gas supply passage 26b is formed.

  A first pressure regulator (regulator) 26aa is provided in the first branch compressed gas supply passage 26a so that the pressure (indoor pressure) P1 of the gas C in the first chamber 27a can be stored at a preset first pressure P1c. Configure as follows. Further, the second branch compressed gas supply passage 26b is provided with a second pressure regulator (regulator) 26ba, and the pressure (indoor pressure) P2 of the gas C in the second chamber 27b is accumulated at a preset second pressure P2c. Configure as you can.

  The first pressure P1c is set to a value that is not so high that the maximum pressure Pmax in the cylinder does not exceed the allowable maximum pressure immediately after the start of the supercharging assistance by the gas C, and the second pressure P2c is the supercharging assistance. Even in the latter half of the period, the gas C is set to a value that can sufficiently accumulate the gas C that can be supplied into the cylinder.

  At the same time, the first chamber 27a and the second chamber 27b are communicated with each other via a check valve 27c, and the check valve 27c is connected to a preset pressure value P1a in which the indoor pressure P1 of the first chamber 27a is set in advance. When the pressure decreases, the valve is opened by a differential pressure ΔP (= P2−P1) between the indoor pressure P2 of the second chamber 27b and the indoor pressure P1 of the first chamber 27a. In this case, since the chamber pressure P2 of the second chamber 27b is initially the second pressure P2c, the check valve 27c has a differential pressure ΔP that is equal to the valve opening differential pressure ΔPca (= P2c−P1a). Will be opened.

  The first pressure P1c, the second pressure P2c, and the set pressure value P1a are set based on experimental results and the like. Normally, the second pressure P2c is stored in the check valve 27c in order to accumulate as much gas C as possible. Although it is set higher than the first pressure P1c in a range where the valve is not opened, depending on the type of engine, the second pressure P2c may be set lower than the first pressure P1c. . In short, the first pressure regulator 26aa can be used to set the first pressure P1c, and the second pressure regulator 26ba can be used to set the second pressure P2c separately.

  In the configuration of FIG. 3, the valve element 27ca of the check valve 27c is pressed against the valve seat 27cb by a spring 27cc. While the differential pressure ΔP = P2−P1 acting on the valve body 27ca is smaller than the preset valve opening differential pressure ΔPca (ΔP <ΔPca), as shown in FIG. 4, the valve body 27ca is seated on the valve seat 27cb. Then, the gas C in the second chamber 27b is prevented from being supplied to the first chamber 27a. Further, when the differential pressure ΔP acting on the valve body 27ca becomes equal to or greater than the valve opening differential pressure ΔPca (ΔP ≧ ΔPca), the force based on the differential pressure ΔP rather than the biasing force of the spring 27ca, as shown in FIG. Thus, the valve body 27ca is separated from the valve seat 27cb, and the gas C in the second chamber 27b is supplied to the first chamber 27a.

  For safety of the gas storage container 27, as shown in FIG. 3, an adjustment valve (safety valve) 27d for adjusting the maximum pressure of the indoor pressure P1 in the first chamber 27a of the gas storage container 27 is provided in the first chamber 27a. And an adjustment valve (safety valve) 27e for adjusting the maximum pressure of the indoor pressure P2 in the second chamber 27b is provided in the second chamber 27b.

  With this configuration, the engine 1 is one of the EGR passage 17 for recirculating a part Ge of the exhaust gas G into the cylinder, the part Gp of the exhaust gas G of the engine 1, the air Aa, and a mixed gas thereof. A gas compressor 25 that compresses the gas C, a gas storage container 27 that stores the gas C compressed by the gas compressor 25, and a gas storage supply passage 28 that connects the gas storage container 27 and the intake passage 12. It is prepared for.

  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 configured with a three-way switching valve as shown in FIGS. 15 and 16.

  In the flow path switching device 30 shown in FIGS. 15 and 16, the shutter gas 30p is moved by moving the rod 30b of the driving high-speed cylinder 30a by inserting the driving gas Ap and extracting the air Ae on the back surface of the piston. Move. Thereby, as shown in FIG. 15, the gas storage supply passage 28 side is closed, and the upstream side 12a and the downstream side 12b of the intake passage 12 are communicated. Further, as shown in FIG. 16, the upstream side 12 a side of the intake passage 12 is closed, and the stored gas supply passage 28 and the downstream side 12 b of the intake passage 12 are communicated.

  A control device 40 called an engine control unit (ECU) is provided to control the overall operation of the engine 1 and the above-described devices. The control device 40 uses the pressure in the intake manifold 11 a and the gas storage container 27. The indoor pressures P1, P2, the engine rotational 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 gas C in the gas storage container 27 is controlled. The amount (pressure P1, P2), the mixing ratio of the exhaust gas Gp and the air Aa is adjusted and controlled.

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

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

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

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

  Further, in this supercharging assist method for the internal combustion engine, the flow path switching device 30 configured by a three-way switching valve as shown in FIGS. 15 and 16 for shutting off the EGR gas Ge and fresh air A and supplying the gas C. To do.

  In these controls, the control device 40 detects the engine rotation speed Ne, the engine air amount (Mo, Me), the engine fuel amount (fuel injection amount) Q, the detected internal pressures P1, P2, etc. in the gas storage container 27. Based on these, the pressure regulating 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 supercharging assistance 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.

  In this supercharging assistance method, immediately after the supercharging assistance is started, the gas C accumulated at the first pressure P1c preset in the first chamber 27a of the gas storage container 27 is supplied into the cylinders of the engines 1 and 1A. When the supply causes the indoor pressure P1 of the first chamber 27a to be lower than a preset pressure value P1a, the indoor pressure P2 of the second chamber 27b (a pressure set separately from the indoor pressure P1) and the first pressure The check valve 27c provided in the communication path between the first chamber 27a and the second chamber 27b is opened by the differential pressure ΔP (= P2−P1) with respect to the indoor pressure P1 of the chamber 27a, and pressure is accumulated in the second chamber 27b. The supplied gas C is supplied to the first chamber 27a, and supercharging assistance is performed until the supercharging assistance end is determined.

  According to the supercharging assist method and the engine (internal combustion engine) 1, 1A described above, during transient operation of the engine 1, 1A such as when the vehicle equipped with the engine 1, 1A is suddenly accelerated or started, the gas Immediately after starting the supercharging assistance using C, the supercharging assistance is performed in a state where the apparent volume of the gas storage container 27 of only the first chamber 27a in which the indoor pressure P1 is not so high, the cylinder internal pressure in the low speed range The maximum value Pmax of the first chamber 27a can be suppressed, and the gas C in the second chamber 27b is supplied to the first chamber 27a after the medium speed at which the indoor pressure P1 of the first chamber 27a decreases. Supercharging assistance can be performed, and a decrease in the excess air ratio during the latter half of the supercharging assistance can be prevented.

  In other words, in the low speed range at the start of supercharging assistance, the apparent volume of the gas storage container 27 can be made small, and the indoor pressure P1 can be set not to be too high to suppress the maximum value Pmax of the cylinder internal pressure. In the latter half of the supercharging assistance, the amount of gas C that can be supplied can be increased, the apparent volume of the gas storage container 27 can be increased, and the excess air ratio by supercharging assistance can be increased. In addition, it is possible to automatically perform two-stage supercharging assistance with a relatively simple configuration in which a check valve is provided.

  FIG. 6 shows the change over time in the internal pressure of each cylinder when the two-stage supercharging assistance is performed, and FIG. 7 shows the excess air ratio for each cycle. The two-stage supercharging assistance in FIG. 6 is intermediate between the case of the 40 liter gas storage container 27 in FIG. 11 and the case of the 80 liter gas storage container 27 in FIG. It can be seen that the maximum value of the internal pressure of the cylinder is smaller than that in FIG. Further, from FIG. 7, the excess air ratio by the two-stage supercharging assistance is the same as the case where the 40 liter gas storage container 27 is used up to the 4th cycle, but after the 5th cycle, the 40 liter gas storage container is used. It turns out that it is larger than the case where 27 is used.

  A supercharging assist method and an internal combustion engine of an internal combustion engine according to the present invention use a gas compression device to store a part of exhaust gas, air, and any one of these mixed gases in a gas storage container, and the load is rapidly increased. In an internal combustion engine that temporarily suppresses NOx emission in a transient state and improves acceleration performance while temporarily increasing the gas in an increasing transient state, the gas stored in the gas storage container is excessively supplied. When performing subsidy assistance, immediately after the start of supercharging assistance, the pressure of the gas from the gas storage container can be lowered to suppress the maximum value of the cylinder internal pressure, and in the second half of supercharging assistance, a sufficient amount of gas is supplied to the cylinder. It is possible to secure a sufficient excess air ratio by supplying the air inside.

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

1, 1A, 1X, 1Y, 1Z engine (internal combustion engine)
11 Engine body 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 first chamber 27b second chamber 27c check valve 28 gas storage supply passage 30 flow path Switching device 40 Control device A Fresh air Aa Air Ac Accelerator opening C Gas G Exhaust gas Ge EGR gas Gp Part of exhaust gas P1 Indoor pressure P1a of first chamber Set pressure value P1c First pressure P2 Indoor pressure of second chamber P2c second pressure ΔP differential pressure (= P2-P1)
ΔPca Differential pressure for valve opening (= P2c-P1a)

Claims (3)

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,
The gas pressure supplied to the second chamber of the gas storage container is adjusted to a predetermined second pressure so that the gas pressure supplied to the first chamber of the gas storage container becomes a predetermined first pressure. While supplying the gas discharged from the gas compression device to the first chamber and the second chamber,
Immediately after the start of supercharging assistance, the gas accumulated at the first pressure in the first chamber is supplied into the cylinder, and this supply reduces the indoor pressure in the first chamber below a preset pressure value. The supercharging of the internal combustion engine is characterized in that the supercharging assistance is performed until the supercharging assistance end is determined by supplying the gas accumulated in the second chamber with the second pressure to the first chamber. Auxiliary method.   When the indoor pressure in the first chamber drops below a preset pressure value, a check valve provided in the communication path between the first chamber and the second chamber is connected to the indoor pressure in the second chamber and the The supercharging assist of the internal combustion engine according to claim 1, wherein the gas accumulated in the second chamber is supplied to the first chamber by opening the valve by a differential pressure with respect to the chamber pressure in the first chamber. Method. 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,
Forming the gas storage container in a plurality of chambers including at least a first chamber and a second chamber;
A pressure accumulation gas supply passage for supplying the gas into the cylinder is connected to the first chamber;
A first passage for supplying gas discharged from the gas compression device;
A second passage for supplying the gas discharged from the gas compression device to the first chamber of the gas storage container from the first passage;
A third passage for supplying the gas discharged from the gas compression device to the second chamber of the gas storage container from the first passage;
A first adjuster provided in the second passage and configured to adjust a gas pressure supplied to the first chamber to a predetermined first pressure;
A second regulator that is provided in the third passage and adjusts the gas pressure supplied to the second chamber to a predetermined second pressure;
The chamber pressure in the second chamber accumulated by the gas from the gas compressor can be set separately with respect to the chamber pressure in the first chamber accumulated by the gas from the gas compressor. ,
The second chamber communicates with the first chamber via a check valve, and the check valve is operated when the indoor pressure in the first chamber drops below a preset pressure value. An internal combustion engine configured to be opened by a differential pressure between an indoor pressure in two chambers and an indoor pressure in the first chamber.

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