JP2009228651A - Charging device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging device for an engine improving output response and preventing formation of black smoke in acceleration. <P>SOLUTION: If it is determined that an acceleration condition of the engine 1 is a prescribed acceleration condition when part of exhaust gas of the engine 1 is recirculated to an intake side via an EGR valve 22, compressed air supplied from a main air tank 44 is directly supplied into an intake port 54 of each cylinder from an air injection nozzle 58 by controlling an air control valve 32 provided with corresponding to each cylinder. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air supply device for an engine, and more particularly to an air supply device for supplying air to an engine provided with an EGR device.

Conventionally, an EGR passage that connects the intake passage and the exhaust passage of the engine is provided, and a part of the exhaust of the engine is recirculated to the intake side through the EGR passage, thereby reducing the combustion temperature in the combustion chamber and the engine. An EGR device is used in which the excess air ratio is reduced to suppress engine NOx (nitrogen oxide) emissions.
In such an EGR device, an EGR valve for adjusting the exhaust gas recirculation amount is provided in an EGR passage communicating the exhaust passage and the intake passage of the engine. For example, the control is performed as follows.

That is, an optimum EGR rate corresponding to various operating states of the engine is obtained in advance by experiments or the like, and the opening degree of the EGR valve for obtaining such an EGR rate is determined and stored in advance. Then, the EGR valve is controlled to the stored opening degree so that the optimum EGR rate is obtained in accordance with the actual operating state of the engine.
Such control of the EGR device is disclosed in, for example, Patent Document 1. In the EGR device of Patent Document 1, when performing the above-described control of the EGR valve, a target intake air amount for obtaining an EGR rate obtained according to the operating state of the engine is determined, and the actual intake air amount is determined as the target intake air amount. By correcting the opening degree of the EGR valve so as to be equal to the air amount, an optimal EGR rate can be obtained with high accuracy. Further, in the EGR device of Patent Document 1, such an EGR valve is controlled during sudden acceleration of the engine, and the EGR valve is fully closed to cope with a delay in the intake air amount increase due to a response delay of the supercharger. Then, since NOx in the exhaust gas increases at this time, an increase in NOx is prevented by temporarily controlling the EGR valve in the opening direction during sudden acceleration of the engine.
JP 2007-247540 A

  However, when the engine shifts to the acceleration state while the EGR valve is controlled as described above, the EGR rate is decreased in order to obtain a sufficient amount of fresh air corresponding to the acceleration state. Thus, the EGR valve is controlled in a direction to decrease the opening degree of the EGR valve in order to increase the excess air ratio. However, since there is a response delay in the EGR valve, there may be a case where the excess air ratio required for accelerating the engine cannot be secured due to this response delay. In particular, when the engine is operating at a low speed and a low load, the opening of the EGR valve is increased and a large amount of exhaust gas is recirculated to the intake side. In the meantime, a large amount of exhaust gas is continuously recirculated due to a delay in response of the EGR valve, and the amount of fresh air is greatly insufficient. As a result, there is a problem that not only the output necessary for accelerating the engine cannot be obtained quickly, but also black smoke is generated due to the temporary decrease in the excess air ratio with respect to the excess air ratio required during acceleration. Arise.

Further, as in the EGR device of Patent Document 1, if the exhaust gas recirculation amount is temporarily increased during acceleration of the engine, the NOx emission amount can be suppressed, but the excess air ratio is not improved. It cannot be prevented.
The present invention has been made in view of such problems, and an object thereof is to provide an air supply device for an engine that prevents generation of black smoke during acceleration and improves output response. There is to do.

  In order to achieve the above object, an air supply device for an engine according to the present invention includes an EGR device that recirculates a part of engine exhaust to the intake side of the engine, a main air tank that accumulates compressed air, and an intake passage of the engine Separately from the intake via the air, the air supply means for supplying the compressed air accumulated in the main air tank into the intake port of the engine, the EGR device is controlled according to the operating state of the engine, and the EGR When it is determined that the acceleration state of the engine is a predetermined acceleration state when a part of the exhaust of the engine is recirculated to the intake side by the device, the air supply means is controlled to control the intake air from the air supply means. And a control means for supplying the compressed air into the port (claim 1).

  According to the engine air supply apparatus configured as described above, the control means controls the EGR apparatus in accordance with the operating state of the engine. When it is determined that the acceleration state of the engine is the predetermined acceleration state when a part of the exhaust gas is recirculated to the intake side by the EGR device, the control means controls the air supply means and is stored in the main air tank. The compressed air is supplied from the air supply means into the intake port of the engine.

  In the engine air supply device, the control means may be configured such that the acceleration state of the engine is the predetermined acceleration state when a part of the exhaust of the engine is recirculated to the intake side by the EGR device. When the determination is made, the EGR device is controlled so that the recirculation amount of the exhaust gas by the EGR device becomes a recirculation amount corresponding to the acceleration state of the engine, and the fresh air intake amount of the engine through the intake passage generated at this time is controlled. The compressed air is supplied from the air supply means into the intake port by controlling the air supply means in response to the shortage of the above (Claim 2).

  According to the engine air supply apparatus configured as described above, when the engine acceleration state is determined to be the predetermined acceleration state when a part of the exhaust gas is recirculated to the intake side by the EGR device, the control means performs the EGR. The EGR device is controlled so that the exhaust gas recirculation amount by the device becomes a recirculation amount corresponding to the acceleration state of the engine. By performing such control, when the recirculation amount of the exhaust gas by the EGR device is controlled so as to decrease from before the acceleration, the intake air amount of the engine through the intake passage is caused by the response delay of the EGR device. Takes time to increase to an amount corresponding to the acceleration state of the engine. Therefore, the control means supplies the compressed air into the intake port from the air supply means by controlling the air supply means in response to the shortage of the fresh air intake amount of the engine via the intake passage generated at this time.

In the engine air supply apparatus, when the compressed air is supplied from the air supply means into the intake port, the control means enters the intake port as the engine speed increases. The air supply means is controlled so that the supply amount of the compressed air per unit time increases (claim 3).
Alternatively, in the engine air supply apparatus, when the compressed air is supplied from the air supply means into the intake port, the control means supplies the intake port to the intake port as the engine load increases. The air supply means is controlled so that the supply amount of the compressed air per unit time increases (Claim 4).

According to the engine air supply apparatus configured in this way, the acceleration state of the engine is a predetermined acceleration state, and when the compressed air is supplied from the air supply means into the intake port, the engine speed increases. Alternatively, the amount of compressed air supplied into the intake port per unit time is increased as the engine load increases.
In the engine air supply apparatus, the control means supplies the compressed air from the air supply means into the intake port when it is determined that the operating state of the engine is not the predetermined acceleration state. The system is stopped (claim 5).

According to the engine air supply apparatus configured as described above, when it is determined that the engine operating state is not the predetermined acceleration state, the control unit stops the supply of compressed air from the air supply unit to the intake port. To do.
In the engine air supply device, the main air tank is provided separately from the engine, and the air supply means is mounted on the engine, and compressed air is supplied from the main air tank via an air supply pipe. A sub air tank, an air injection nozzle having an air injection port in the intake port, the sub air tank and the air injection nozzle, and the intake air from the sub air tank through the air injection nozzle. An air control valve for adjusting the amount of compressed air supplied into the port, and the control means controls the air control valve to supply compressed air from the air injection nozzle into the intake port. (Claim 6).

  According to the engine air supply apparatus configured as described above, the compressed air accumulated in the main air tank provided apart from the engine is supplied to the sub air tank attached to the engine via the air supply pipe. Is done. When the acceleration state of the engine is a predetermined acceleration state and compressed air is supplied into the intake port, the control means controls the air control valve so that the compressed air in the sub air tank passes through the air injection nozzle. Supplied into the intake port.

In the engine air supply device, the air supply means is interposed in the air supply pipe to allow air to flow from the main air tank to the sub air tank, and from the sub air tank to the main air tank. A check valve is provided to block the flow of air (claim 7).
According to the engine air supply apparatus configured as described above, the check valve interposed in the air supply pipe allows air to flow from the main air tank to the sub air tank, and from the sub air tank to the main air tank. The air flow is blocked.

  According to the air supply device for an engine of the present invention, when a part of the exhaust gas is recirculated to the intake side by the EGR device, if the acceleration state of the engine becomes a predetermined acceleration state, it is accumulated in the main air tank. Compressed air is supplied directly from the air supply means into the engine intake port. As a result, even if the intake air amount through the intake passage is insufficient due to the response delay of the EGR device, the compressed air is supplied from the air supply means into the intake port separately from the intake air through the intake passage. It is possible to satisfactorily prevent the generation of black smoke and the engine output shortage due to the decrease in the excess rate. In particular, since the compressed air is supplied directly into the intake port, the generation of black smoke and the reduction in output can be prevented with high responsiveness.

  According to the engine air supply device of claim 2, when it is determined that the acceleration state of the engine is the predetermined acceleration state when a part of the exhaust gas is recirculated to the intake side by the EGR device, the control means The EGR device is controlled so that the exhaust gas recirculation amount by the EGR device becomes a recirculation amount corresponding to the acceleration state of the engine. When the exhaust gas recirculation amount by the EGR device is controlled so as to decrease from before the acceleration, the intake air amount of the engine via the intake passage corresponds to the acceleration state of the engine due to the response delay of the EGR device. It takes time to increase to the air volume, but the control means controls the air supply means in response to the shortage of the fresh air intake amount through the intake passage that occurs at this time, so that the air supply means and the intake port Since the compressed air is directly supplied to the battery, it is possible to quickly and accurately prevent the generation of black smoke and the shortage of output accompanying the decrease in the excess air ratio.

  Further, as the engine speed increases during the acceleration of the engine, the amount of fresh air required for the engine increases. According to the engine air supply device of claim 3, the engine acceleration state is a predetermined acceleration. When the compressed air is supplied from the air supply means into the intake port, the amount of compressed air supplied to the intake port per unit time increases as the engine speed increases. In response to the increase in the number, the supply of compressed air into the intake port can accurately compensate for the shortage of the fresh air intake amount.

  Further, as the engine load increases during the acceleration of the engine, the fresh air intake amount required for the engine increases. According to the engine air supply device of claim 4, the engine acceleration state is a predetermined acceleration state. When the compressed air is supplied from the air supply means into the intake port, the amount of compressed air supplied into the intake port per unit time increases as the engine load increases. In response to the increase, supply of compressed air into the intake port makes it possible to accurately compensate for the shortage of fresh air intake.

  According to the fifth aspect of the present invention, when the engine operating state is not in the acceleration state, the supply of compressed air from the air supply means into the intake port is stopped. Thus, when a part of the exhaust gas is recirculated to the intake side and the acceleration state of the engine becomes the predetermined acceleration state, the compressed air in the main air tank can be intensively used without waste. Therefore, when the main air tank is replenished with compressed air using an air pump that consumes a part of engine output as driving energy, such as an air pump driven by an engine, the work of the air pump is reduced. It becomes possible to reduce and improve the fuel consumption of the engine.

  According to the engine air supply device of claim 6, the sub air tank in a state where compressed air is supplied and accumulated from the main air tank provided separately from the engine to the sub air tank mounted on the engine. The compressed air inside is supplied into the intake port. As a result, it is possible to quickly supply a necessary amount of compressed air into the intake port without being affected by the supply delay of compressed air from the main air tank.

  According to the air supply device for an engine of claim 7, even if the pressure in the intake port of the engine exceeds the pressure of the compressed air in the main air tank, the air supply pipe is not provided. The check valve thus made can prevent the backflow of air from the sub air tank to the main air tank.

Hereinafter, an air supply device for an engine according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall configuration diagram of an engine system including an in-line 6-cylinder diesel engine (hereinafter referred to as an engine) 1 to which an engine air supply device according to an embodiment of the present invention is applied. A configuration of an engine air supply device according to an embodiment of the present invention will be described.
The engine 1 includes a high-pressure accumulator chamber (hereinafter referred to as a common rail) 2 common to each cylinder, and high-pressure fuel supplied from a fuel injection pump (not shown) and stored in the common rail 2 is supplied to an injector 4 provided in each cylinder. Then, fuel is injected from each injector 4 into each cylinder.

  The intake pipe (intake passage) 6 is equipped with a turbocharger 8, and intake air drawn from an air cleaner (not shown) flows from the intake pipe 6 into the compressor 8 a of the turbocharger 8. The intake air supercharged by the compressor 8a is introduced into the intake manifold 14 via the intercooler 10 and the intake control valve 12, and then distributed to each cylinder. An intake air amount sensor 16 for detecting the amount of air sucked into the engine 1, that is, the amount of fresh air, is provided upstream of the compressor 8 a of the intake pipe 6.

  On the other hand, an exhaust port (not shown) through which exhaust is discharged from each cylinder of the engine 1 is connected to an exhaust pipe 20 via an exhaust manifold 18. An EGR passage 26 is provided between the exhaust manifold 18 and the intake manifold 14 so as to communicate the exhaust manifold 18 and the intake manifold 14 via an EGR valve 22 and an EGR cooler 24. By changing, the exhaust gas recirculation amount from the exhaust manifold 18 to the intake manifold 14 can be adjusted. Therefore, in this embodiment, the EGR valve 22 and the EGR passage 26 correspond to the EGR device of the present invention.

The exhaust pipe 20 passes through the turbine 8 b of the turbocharger 8 and is connected to the exhaust aftertreatment device 30 via the exhaust throttle valve 28. The rotating shaft of the turbine 8b is connected to the rotating shaft of the compressor 8a so that the turbine 8b receives the exhaust flowing in the exhaust pipe 20 and drives the compressor 8a.
The exhaust aftertreatment device 30 has a function of purifying exhaust gas by removing particulates and NOx in the exhaust gas discharged from the engine 1 from the exhaust gas. The exhaust aftertreatment device 30 has a function similar to that of an exhaust aftertreatment device that is currently generally used, and a detailed description thereof is omitted here.

  Each cylinder of the engine 1 is provided with an air control valve 32 for supplying compressed air to each cylinder. The compressed air stored in the first sub air tank 36 is supplied to each of the air control valves 32 provided one by one corresponding to each cylinder of the first cylinder group 34 among the six cylinders. It has become. Further, the compressed air stored in the second sub air tank 40 is supplied to each of the air control valves 32 provided for each cylinder of the second cylinder group 38. .

  The first sub air tank 36 and the second sub air tank 40 are supplied with compressed air through a common air supply pipe 42 from a main air tank 44 provided separately from the engine 1. Air flows from the main air tank 44 side to the first sub air tank 36 side and the second sub air tank 40 side in the air supply pipe 42 before branching toward each of the first sub air tank 36 and the second sub air tank 40. And a check valve 46 that interrupts the flow of air from the first sub air tank 36 side and the second sub air tank 40 side to the main air tank 44 side is interposed. The main air tank 44 is supplied with compressed air adjusted within a predetermined pressure range by an air pump 48 driven by the power of the engine 1 and accumulated therein.

FIG. 2 is a schematic cross-sectional view in the vertical direction showing the configuration of the intake port corresponding to one cylinder in the cylinder head portion of the engine 1 and its surroundings. The configuration shown in FIG. 2 representatively shows one of the cylinders of the first cylinder group 34, but each cylinder of the first cylinder group 34 and the second cylinder group 38 has the same configuration. ing.
As shown in FIG. 2, the other end of the intake port 54 whose one end opens into the combustion chamber 52 is opened in the side surface portion of the cylinder head 50 of the engine 1. An intake manifold 14 having a U-shaped cross section is attached so as to cover 54 openings. The opening of the intake port 54 on the combustion chamber 52 side is opened and closed by an intake valve 56 driven by a valve mechanism (not shown), and the intake air supplied from the intake pipe 6 to the intake manifold 14 is opened by the intake valve 56. It has been introduced in.

  A first sub air tank 36 is attached to the upper portion of the intake manifold 14 with the air control valve 32 interposed therebetween. An air injection nozzle 58 projecting from the lower portion of the air control valve 32 extends through the upper wall of the intake manifold 14 into the intake port 54 and has an air injection port 58 a in the intake port 54. . The inside of the first sub air tank 36 and the air injection nozzle 58 can communicate with each other via the air control valve 32. By opening the air control valve 32, the compressed air in the first sub air tank 36 is converted into the air injection nozzle. The air supply port 58 is supplied into the intake port 54.

As described above, in the present embodiment, the air control valve 32, the first sub air tank 36, the second sub air tank 40, the air supply pipe 42, and the air injection nozzle 58 constitute the air supply means of the present invention. The supply of compressed air into the intake port 54 via the air injection nozzle 58 will be described in detail later.
The engine 1 is provided with an ECU 60 as a control device for performing comprehensive control related to the engine 1 including operation control of the engine 1. The ECU 60 includes a CPU, a memory, a timer counter, and the like. The ECU 60 calculates various control amounts for the engine 1 and controls various devices based on the control amounts.

  On the input side of the ECU 60, in order to collect information necessary for various controls, in addition to the intake air sensor 16, the air pressure sensor 62 that detects the pressure of the compressed air in the main air tank 44, and the crank angle of the engine 1 are detected. Various sensors are connected such as a crank angle sensor 64 that detects the amount of depression of an accelerator pedal (not shown) and an accelerator opening sensor 66 that detects the amount of depression. On the other hand, on the output side of the ECU 60, various devices such as the injector 4, the intake control valve 12, the EGR valve 22, the exhaust throttle valve 28, the air control valve 32, and the air pump 48 of each cylinder that are controlled based on the calculated control amount. Is connected.

  As one operation control of the engine 1, the ECU 60 performs calculation of the fuel supply amount to each cylinder of the engine 1 and fuel supply control from the injector 4 based on the calculated fuel supply amount. The fuel supply amount (main injection amount) necessary for the operation of the engine 1 is determined in advance based on the engine speed obtained from the detection signal of the crank angle sensor 64 and the depression amount of the accelerator pedal detected by the accelerator opening sensor 66. It is determined by reading from the stored map. The amount of fuel supplied to each cylinder is adjusted by the valve opening time of the injector 4, and each injector 4 is driven to open in a driving time corresponding to the determined fuel amount, and main injection is performed in each cylinder. Thus, the amount of fuel necessary for the operation of the engine 1 is supplied.

Further, the ECU 60 operates the air pump so that the pressure of the compressed air in the main air tank 44 falls within an appropriate pressure range based on the pressure of the compressed air in the main air tank 44 detected by the air pressure sensor 62 attached to the main air tank 44. The operation of 48 is controlled.
Further, the ECU 60 adjusts the opening degree of the EGR valve 22 provided in the EGR passage 26 according to the operating state of the engine 1 and controls the amount of exhaust gas recirculated from the exhaust manifold 18 to the intake manifold 14. The excess air ratio of 1 is controlled to the target excess air ratio.

  The target excess air ratio is obtained as an excess air ratio that can suppress the generation of NOx without deteriorating the combustion state in each combustion chamber of the engine 1 in advance in accordance with various operating states of the engine 1 through experiments or the like. The target air excess ratio map is stored with the number of revolutions of the engine 1 and the fuel injection amount by main injection, that is, the engine load as parameters. Further, the ECU 60 stores the opening degree of the EGR valve 22 necessary for setting the excess air ratio of the engine 1 as the target excess air ratio as a target opening degree in the EGR valve target opening degree map.

  The ECU 60 reads out the corresponding target excess air ratio from the target excess air ratio map based on the number of revolutions of the engine 1 and the fuel injection amount by the main injection at that time, and further the EGR valve 22 for obtaining this target excess air ratio. Read the target opening from the target opening map. The ECU 60 controls the opening degree of the EGR valve 22 based on the target opening degree, whereby a part of the exhaust gas of the engine 1 is returned to the intake manifold 14 via the EGR valve 22 and supplied to each cylinder.

  When such control of the EGR valve 22 is performed, when the accelerator pedal is depressed and the engine 1 shifts to the acceleration state, the opening degree of the EGR valve 22 is set so as to secure an output necessary for acceleration. Corresponding to the acceleration state, it is controlled in a decreasing direction from the opening before acceleration. At this time, since a response delay occurs in the EGR valve 22, the opening degree of the EGR valve 22 does not immediately become the target opening degree corresponding to the acceleration state at that time, and more exhaust gas than the necessary amount is recirculated to the intake side. It will be. As a result, if the state where the actual excess air ratio is lower than the target excess air ratio continues for a while, black smoke is generated during that time, or the output required for acceleration cannot be secured and the acceleration performance decreases. there is a possibility. Therefore, the ECU 60 switches the control of the EGR valve 22 depending on whether the acceleration state of the engine 1 is the predetermined acceleration state or not, and controls the air control valve 32 described above when the acceleration state becomes the predetermined acceleration state. Thus, compressed air is supplied from the air injection nozzle 58 to each cylinder.

Hereinafter, the control of the air control valve 32 and the EGR valve 22 by the ECU 60 will be described in detail.
FIG. 3 is a flowchart of control of the air control valve 32 and the EGR valve 22 executed by the ECU 60, and is repeatedly executed at a predetermined control period during the operation of the engine 1.

  When the control is started, in step S1, the ECU 60 corresponds to the excess air corresponding from the target excess air ratio map based on the engine speed obtained from the detection signal of the crank angle sensor 64 and the fuel injection amount by the main injection at that time. The rate is read and set as the target excess air rate. In the next step S2, the ECU 60 reads the opening degree of the EGR valve 22 for setting the excess air ratio of the engine 1 to the target excess air ratio set in step S1 from the target opening degree map and sets it as the target opening degree.

  Further, when the process proceeds to step S3, the ECU 60 obtains a rate of change of the engine speed based on the engine speed obtained from the detection signal of the crank angle sensor 64, and whether or not this rate of change is larger than a predetermined acceleration determination reference value. It is determined whether or not the operating state of the engine 1 is a predetermined acceleration state. That is, the ECU 60 determines that the acceleration state of the engine 1 is the predetermined acceleration state when the change rate of the engine speed is greater than the acceleration determination reference value, and determines that the engine rotation speed change rate is equal to or less than the acceleration determination reference value. Determines that the operating state of the engine 1 is not in a predetermined acceleration state.

When it determines with the driving | running state of the engine 1 not being a predetermined acceleration state by step S3, ECU60 advances a process to step S4, all the air control valves 32 provided for every cylinder are fully closed, and also a process is step S5. Proceed to
In step S5, the ECU 60 determines the actual exhaust gas recirculation amount calculated based on the intake fresh air amount of the engine 1 detected by the intake air amount sensor 16, the fuel injection amount by main injection, and the opening of the EGR valve 22 at that time. The actual excess air ratio that is the actual excess air ratio of the engine 1 is calculated.

  Next, in step S6, the ECU 60 corrects the target opening of the EGR valve 22 set in step S2 in accordance with the deviation between the target excess air ratio set in step S1 and the actual excess air ratio calculated in step S5. To do. That is, when the actual excess air ratio is smaller than the target excess air ratio, the amount of exhaust gas recirculated through the EGR valve 22 is excessive, so that the target opening degree of the EGR valve 22 decreases. It is corrected. On the other hand, when the actual excess air ratio is greater than the target excess air ratio, the amount of exhaust gas recirculated through the EGR valve 22 is too small, so the target opening of the EGR valve 22 increases in the increasing direction. It is corrected.

  In the next step S7, the ECU 60 controls the EGR valve 22 based on the target opening corrected in step S6, and the series of controls in the control cycle is ended. By controlling the EGR valve 22 in this manner, the excess air ratio of the engine 1 corresponds to the operating state of the engine 1 and air that can suppress the generation of NOx without deteriorating the combustion state in each combustion chamber. The excess ratio is adjusted, and good exhaust characteristics can be obtained for the engine 1.

  Also in the next control cycle, control is executed from step S1, and when the process proceeds to step S3 as described above, the ECU 60 determines again whether or not the operating state of the engine 1 is a predetermined acceleration state. Therefore, as long as the operating state of the engine 1 does not become the predetermined acceleration state, the control of the air control valve 32 and the EGR valve 22 in steps S1 to S7 as described above is repeated every control cycle, and the air control valve 32 is in the fully closed state. And exhaust gas recirculation through the EGR valve 22 is performed, and the exhaust characteristics of the engine 1 are maintained well. Accordingly, in this case, compressed air is not supplied from the air injection nozzle 58 into the intake port 54 of each cylinder.

  On the other hand, when the change rate of the engine speed becomes larger than the predetermined acceleration determination reference value in step S3 and the acceleration state of engine 1 is determined to be the predetermined acceleration state, ECU 60 advances the process from step S3 to step S8. In step S8, the ECU 60 controls the EGR valve 22 to the target opening set in step S2 in the control cycle, and proceeds to the next step S9.

In step S9, as in step S5 described above, the ECU 60 is based on the intake fresh air amount of the engine 1 detected by the intake air amount sensor 16, the fuel injection amount by main injection, and the opening of the EGR valve 22 at that time. An actual excess air ratio that is an actual excess air ratio of the engine 1 is calculated from the obtained exhaust gas recirculation amount.
Next, in step S10, the ECU 60 determines from the target control amount map stored in advance according to the deviation between the target excess air ratio set in step S1 and the actual excess air ratio calculated in step S9 in the control cycle. The control amount of the air control valve 32 is read and set as the target control amount. This target control amount map is a map for setting the opening degree of the air control valve 32 required to make the actual excess air ratio of the engine 1 equal to the target excess air ratio. That is, an air control valve for actually obtaining an additional amount of air that needs to be supplied to each cylinder in order to make the actual excess air ratio of the engine 1 equal to the target excess air ratio in various operating states of the engine 1 by experiments or the like. The control amount of 32 is obtained, and the control amount thus obtained is preset in the target control amount map corresponding to the operating state of the engine 1 as the target control amount of the air control valve 32. In the present embodiment, the air control valve 32 is a type of control valve that switches between a fully open state and a fully closed state, and the control amount of the air control valve 32 defines the valve opening time of the air control valve 32. Is set.

  At the time of acceleration of the engine 1, as described above, the intake fresh air amount is temporarily insufficient due to the response delay of the EGR valve 22, and the actual excess air ratio becomes smaller than the target excess air ratio. The target control amount of the air control valve 32 is set so that the amount of air per unit time supplied from the air control valve 32 to each cylinder increases as the deviation between the actual excess air ratio and the target excess air ratio increases. Yes. Accordingly, an amount of compressed air corresponding to a shortage of fresh air intake through the intake pipe 6 generated when the acceleration state of the engine 1 becomes a predetermined acceleration state is supplied from the air control valve 32 to each cylinder. It has become.

  In addition, since the amount of air required for the engine 1 increases as the engine speed increases or the engine load increases during the acceleration of the engine 1, the actual excess air ratio and the target air in the target control amount map When the comparison is made under the condition that the deviation from the excess ratio is the same, as the engine speed increases or the engine load, that is, the fuel injection amount by main injection increases, the air is supplied from the air control valve 32 to each cylinder. The target control amount of the air control valve 32 is set so that the amount of air to be increased.

  Further, in order to suppress the influence on the supply amount of the compressed air due to the pressure fluctuation of the compressed air in the main air tank 44, the target control amount map shows the deviation between the actual air excess rate and the target air excess rate, the engine speed and the engine load. Are compared under the same conditions, the air control valve 32 is configured such that the higher the pressure of the compressed air in the main air tank 44 detected by the air pressure sensor 62, the shorter the valve opening time of the air control valve 32. The target control amount is set.

  The ECU 60 uses the target control amount map set in this way, and in step S10, the deviation between the actual excess air rate and the desired excess air rate, the engine speed at that time obtained from the detection signal of the crank angle sensor 64, Based on the fuel injection amount by the main injection corresponding to the load of the engine 1 and the pressure of the compressed air in the main air tank 44 detected by the air pressure sensor 62, the control amount of the air control valve 32 is read from the target control amount map and the target. If set as the control amount, the process proceeds to the next step S11.

  In step S11, the ECU 60 opens the air control valve 32 corresponding to each cylinder according to the target control amount at a predetermined timing within the period during which the intake valve 56 is open in each cylinder based on the detection signal of the crank angle sensor 64. Let me speak. When the process of step S11 is thus performed, the ECU 60 ends the control cycle and starts the process from step S1 again in the next control cycle. Therefore, as long as it is determined in step S3 that the acceleration state of the engine 1 is the predetermined acceleration state, compressed air is supplied from the air injection nozzle 58 into the intake port 54 of each cylinder as described above.

  Since the air control valve 32 is opened according to the target control amount in this way, compressed air is supplied from the air injection nozzle 58 into the intake port 54 of each cylinder, so that the acceleration state of the engine 1 is a predetermined acceleration state. The shortage of the fresh air intake amount through the intake pipe 6 caused by the response delay of the EGR valve 22 is compensated by the supply of compressed air from the air injection nozzle 58 into the intake port 54 of each cylinder.

At this time, since the check valve 46 is interposed in the air supply pipe 42, even if the pressure in the intake port 54 becomes higher than the pressure of the compressed air supplied from the main air tank 44, Backflow of air from the first sub air tank 36 and the second sub air tank 40 side to the main air tank 44 side can be prevented.
FIG. 4 is a time chart schematically showing the change in the opening degree of the EGR valve 22 and the actual change in the excess air ratio when the air control valve 32 and the EGR valve 22 are controlled as described above.

Assuming that the operating state of the engine 1 has shifted to a predetermined acceleration state at time t1, the ECU 60 changes the target opening degree of the EGR valve 22 from the previous opening degree R1 to the opening degree R2 corresponding to the acceleration state of the engine 1. However, the actual opening of the EGR valve 22 becomes the target opening R2 at time t2 due to a response delay of the EGR valve 22.
The target excess air ratio of the engine 1 is changed from the excess air ratio λ1 before the transition to the acceleration state to the excess air ratio λ2 corresponding to the acceleration state immediately after the operating state of the engine 1 transitions to the predetermined acceleration state at time t1. And changed. However, as described above, due to the response delay of the EGR valve 22, the actual excess air ratio gradually increases as shown by the one-dot chain line in FIG. 4, and reaches the target excess air ratio λ2 at time t2. For this reason, during the period from time t1 to time t2, the intake fresh air amount corresponding to the portion indicated by the netting in FIG.

  Therefore, as described above, an amount of compressed air corresponding to the deviation between the actual excess air ratio and the target excess air ratio is directly supplied from the air injection nozzle 58 into the intake port 54 of each cylinder. As soon as the shortage of the fresh air intake amount via the engine is compensated and the operating state of the engine 1 shifts to the predetermined acceleration state, the excess air ratio can be increased to the target excess air ratio λ2. As a result, it is possible to accurately prevent the generation of black smoke accompanying a decrease in the excess air ratio, and it is possible to prevent a decrease in acceleration performance.

  The compressed air is supplied to each cylinder from the first sub air tank 36 and the second sub air tank 40 mounted on the intake manifold 14 of the engine 1 through the air injection nozzle 58 in the intake port 54 of each cylinder. Therefore, regardless of the position of the main tank 44, when the operating state of the engine 1 shifts to a predetermined acceleration state, a required amount of compressed air is supplied to each cylinder with good responsiveness, and the excess air ratio is immediately set to the target air. It is possible to increase the excess rate to λ2.

  Further, when the operating state of the engine 1 is in a predetermined acceleration state and compressed air is supplied from the air injection nozzle 58 into the intake port 54 of each cylinder, the intake port 54 increases as the rotational speed of the engine 1 increases as described above. Since the air control valve 32 is controlled so that the supply amount of compressed air to the inside per unit time increases, the shortage of the fresh air intake amount is appropriately compensated for in response to the increase in the engine speed during acceleration. be able to.

  In addition, when the operating state of the engine 1 is in a predetermined acceleration state and compressed air is supplied from the air injection nozzle 58 to the intake port 54 of each cylinder, the intake port 54 increases as the load of the engine 1 increases as described above. Since the air control valve 32 is controlled so that the supply amount of compressed air per unit time increases, it is possible to appropriately compensate for the shortage of the fresh air intake amount corresponding to the increase in the engine load during acceleration. it can.

  In the control of the EGR valve 22 and the air control valve 32 according to the flowchart of FIG. 3, when the control as described above is performed because the operation state of the engine 1 is the predetermined acceleration state, the change in the engine speed is changed. If the rate is equal to or less than the acceleration determination reference value and it is determined in step S3 that the operating state of the engine 1 is not the predetermined acceleration state, the ECU 60 proceeds from step S3 to step S4. As a result, the ECU 60 fully closes the air control valves 32 of the respective cylinders in step S4, stops the supply of compressed air from the air injection nozzle 58 to the intake port 54, and then performs steps S5 to S7 as described above. Perform the process. Accordingly, since the supply of compressed air from the air injection nozzle 58 to the intake port 54 is limited to the case where the acceleration state of the engine 1 is a predetermined acceleration state, the work amount of the air pump 48 that replenishes the main air tank 44 with the compressed air. The fuel consumption of the engine 1 that drives the air pump 48 can be improved.

Although the description of the air supply device for an engine according to one embodiment of the present invention is finished above, the present invention is not limited to the above embodiment.
For example, in the above embodiment, the cylinders of the engine 1 are divided into the first cylinder group 34 and the second cylinder group 38, the first sub air tank 36 is provided for the first cylinder group 34, and the second cylinder group 38 In contrast, although the second sub air tank 40 is provided, a single sub air tank common to all cylinders may be provided, or a sub air tank may be provided independently for each cylinder. In other words, the number of sub air tanks can be variously changed as necessary, and this also applies to the number of main air tanks.

In the above embodiment, the check valve 46 is interposed in the air supply pipe 42 before branching toward the first sub air tank 36 and the second sub air tank 40. It is not limited to. For example, each of the branched air supply pipes 42 may be interposed, or may be incorporated in each of the air control valves 32.
In the above embodiment, the air control valve 32 is a type of control valve that switches between the fully open state and the fully closed state. By controlling the valve opening time of the air control valve 32, the air control valve 32 is controlled to the inside of the intake port 54. Although the amount of compressed air supplied to the air is adjusted, the type and control method of the air control valve 32 are not limited to this. For example, the same type of air control valve 32 as in the above embodiment may be used, and the amount of compressed air supplied from the air injection nozzle 58 to the intake port 54 may be adjusted by duty control. Alternatively, the compressed air from the air injection nozzle 58 to the intake port 54 is controlled by controlling the opening of the air control valve using an air control valve that can continuously change the opening between fully closed and fully open. The supply amount may be adjusted.

Furthermore, in the said embodiment, although the air pump 48 was driven with the engine 1, the form of an air pump is not limited to this, For example, you may use an electrically driven air pump.
Further, the control method of the EGR valve 22 is not limited to that used in the above embodiment, and various known methods can be employed. Regardless of which method is used, as long as the exhaust gas recirculation amount is adjusted by controlling the EGR device such as the EGR valve 22, there is an insufficient excess air ratio due to the response delay of the EGR device during acceleration of the engine 1. Therefore, the same effect can be obtained by applying the present invention.

Furthermore, in the above embodiment, from the amount of fresh air intake of the engine 1 detected by the intake air amount sensor 16, the amount of fuel injected by main injection, and the exhaust gas recirculation amount obtained based on the opening of the EGR valve 22 at that time, Although the actual excess air ratio is calculated, the calculation method of the excess air ratio is not limited to this, and various known methods can be employed.
In the above embodiment, whether or not the operating state of the engine 1 is the predetermined acceleration state is determined based on whether or not the rate of change of the engine speed is greater than the acceleration determination reference value. The determination method of whether or not is not limited to this. For example, by determining whether the rate of change of the accelerator pedal depression amount or the rate of change of the engine load, such as the fuel injection amount due to the main injection, is greater than the corresponding acceleration determination reference value, the engine 1 can perform a predetermined acceleration. You may make it determine whether it is in a state. Alternatively, it may be determined that the acceleration state is only during acceleration from a predetermined low speed / low load operation in which a large amount of exhaust gas recirculation is performed.

Furthermore, in the above embodiment, the fuel injection amount by the main injection is used as the load of the engine 1, but the load of the engine 1 is not limited to this, and for example, the depression amount of the accelerator pedal is used. Also good.
In the above embodiment, an in-line 6-cylinder diesel engine is used as the engine 1. However, the number of cylinders, the type, and the like of the engine 1 are not limited thereto, and any engine having an EGR device may be used. It is possible to apply.

1 is an overall configuration diagram of an engine system having an engine to which an engine air supply device according to an embodiment of the present invention is applied. It is a schematic sectional drawing which shows the structure of the intake port of the engine of FIG. 1, and its periphery. It is a flowchart of the control with respect to the air control valve and EGR valve which are performed with the engine of FIG. It is a time chart which shows the change of the EGR valve opening degree in the control performed according to the flowchart of FIG. 3, and the change of an excess air ratio.

Explanation of symbols

1 Engine 6 Intake pipe (intake passage)
22 EGR valve (EGR device)
26 EGR passage (EGR device)
32 Air control valve (air supply means)
36 1st sub air tank (air supply means)
40 Second sub air tank (air supply means)
42 Air supply pipe (air supply means)
44 Main air tank 46 Check valve 54 Intake port 58 Air injection nozzle (air supply means)
60 ECU (control means)

Claims (7)

An EGR device that recirculates part of the exhaust of the engine to the intake side of the engine;
A main air tank that accumulates compressed air;
Air supply means for supplying compressed air accumulated in the main air tank into the intake port of the engine separately from intake through the intake passage of the engine;
The EGR device is controlled according to the operating state of the engine, and it is determined that the acceleration state of the engine is a predetermined acceleration state when a part of the engine exhaust is recirculated to the intake side by the EGR device. And a control means for controlling the air supply means to supply the compressed air from the air supply means into the intake port.   When the control means determines that the acceleration state of the engine is the predetermined acceleration state when a part of the exhaust of the engine is recirculated to the intake side by the EGR device, the return of the exhaust gas by the EGR device is returned. The EGR device is controlled so that the flow rate becomes the recirculation amount corresponding to the acceleration state of the engine, and the air supply is performed corresponding to the shortage of the fresh air intake amount of the engine via the intake passage that occurs at this time. The engine air supply apparatus according to claim 1, wherein the compressed air is supplied into the intake port from the air supply means by controlling the means.   The control means supplies the compressed air per unit time into the intake port as the engine speed increases when the compressed air is supplied from the air supply means into the intake port. The air supply device for an engine according to claim 1, wherein the air supply means is controlled so as to increase the amount.   When the compressed air is supplied into the intake port from the air supply means, the control means supplies the compressed air per unit time into the intake port as the engine load increases. The air supply device for an engine according to claim 1, wherein the air supply means is controlled so as to increase.   2. The control device according to claim 1, wherein when the operating state of the engine is determined not to be the predetermined acceleration state, the supply of the compressed air from the air supply unit into the intake port is stopped. An air supply device for an engine according to 1. The main air tank is provided apart from the engine,
The air supply means includes
A sub air tank mounted on the engine and supplied with compressed air from the main air tank via an air supply pipe;
An air injection nozzle having an air injection port in the intake port;
An air control valve that is interposed between the sub air tank and the air injection nozzle and adjusts the amount of compressed air supplied from the sub air tank through the air injection nozzle into the intake port,
2. The engine air supply device according to claim 1, wherein the control unit supplies the compressed air from the air injection nozzle into the intake port by controlling the air control valve. 3.   The air supply means is a check valve that is interposed in the air supply pipe and allows air to flow from the main air tank to the sub air tank, and blocks air flow from the sub air tank to the main air tank. The engine air supply device according to claim 6, further comprising:

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