JP2015137550A - Internal combustion engine turbocharging auxiliary system and internal combustion engine turbocharging auxiliary method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine turbocharging auxiliary system and a turbocharging auxiliary system therefor, capable of supplying an appropriate quantity of an auxiliary material for increasing the rotation of a turbine of a turbocharger in a turbocharging system to an exhaust passage upstream of the turbine when an internal combustion engine including the turbocharging system is in a transient state.SOLUTION: A target rotational speed Nr of a turbine 20a is estimated on the basis of an intake air flow F to a compressor 20b of a turbocharger 20 and a boost pressure P downstream of the compressor 20b and an actual rotational speed Na of the turbine 20a is detected, a necessary supply amount Wof an auxiliary material M necessary to increase the actual rotational speed Na to the target rotational speed Nr is calculated, and the auxiliary material M is supplied to an exhaust passage 16 upstream of the turbine 20a by as much as a supply amount W.

Description

  The present invention supplies an auxiliary substance that increases the rotation of the turbine to an exhaust passage upstream of the turbine of the turbocharger of the turbocharger system in a transient state of the internal combustion engine having the turbocharger system. The present invention relates to a supercharging assist system for an internal combustion engine and a supercharging assist method thereof.

  In an internal combustion engine equipped with a turbo-type supercharging system, there is a problem of a turbo lag in which the amount of intake air is insufficient due to a delay in the increase of the intake air supercharging pressure to the target pressure in a transient state where the load increases rapidly. The problem with this turbo lag is that NOx increases due to the EGR amount restriction, soot (煤) and unburned hydrocarbons increase due to insufficient air amount, and the acceleration performance required for starting and overtaking is insufficient due to the suppression of the amount of fuel supplied. To develop.

  In order to solve the problem of the turbo lag, auxiliary substances such as air and water vapor are disposed in the exhaust passage upstream of the turbine of the turbocharger of the turbocharger system in a transient state of the internal combustion engine equipped with the turbocharger system. Has been proposed to increase the amount of gas passing through the turbine, thereby increasing the work of the turbine and increasing the rotational speed of the turbine (for example, Patent Documents 1 and 2). reference). However, in the proposal of these internal combustion engines, no specific proposal has been made regarding a method for controlling the supply amount of the auxiliary substance during the transient state of the internal combustion engine.

  Regarding the supply amount of this auxiliary material, the specific heat, temperature, and supply amount of the auxiliary material to be supplied influence the increase of the work amount of the turbine. Will be invited. For example, if a gas that is lower in temperature than the exhaust temperature or a liquid that requires latent heat of vaporization is supplied as an auxiliary substance more than necessary, the temperature of the exhaust gas supplied to the aftertreatment device will decrease, so the catalyst purification rate There is a concern that will decrease. In addition, when water or water vapor auxiliary substances are supplied more than necessary, condensation occurs in the piping of the exhaust passage, thereby blocking the piping flow path and hindering the flow of exhaust gas, and volume expansion due to temperature changes. There is a concern of promoting thermal cycle fatigue of each device.

  On the other hand, supplying auxiliary substances more than necessary causes deterioration of the economy (cost), and is provided in an exhaust passage downstream of the turbine, such as NOx and PM contained in exhaust gas. The performance of post-treatment devices and the like that purify etc. cannot be fully exhibited, and the durability performance of these devices may be reduced.

International Publication No. 2011/080527 JP 2008-286093 A

  The present invention has been made in view of the above-described situation, and an object of the present invention is to use a turbocharger turbine of the turbocharger system in a transient state of the internal combustion engine including the turbocharger system. It is an object to provide a supercharging assistance system for an internal combustion engine and a supercharging assistance method capable of supplying an auxiliary substance for increasing the rotation of a turbine in an upstream exhaust passage in an optimum amount.

  In order to achieve the above object, a supercharging assist system for an internal combustion engine according to the present invention includes a turbocharger turbine of the turbocharger system in a transient state of the internal combustion engine provided with the turbocharger system. In a supercharging assist system for an internal combustion engine that supplies an auxiliary substance for increasing the rotation of the turbine to an upstream exhaust passage, a control device for controlling the supply amount of the auxiliary substance is the turbocharger after a transient state Target rotational speed calculation means for calculating a target rotational speed of the turbine based on a target intake air flow rate to the compressor and a target supercharging pressure downstream of the compressor, and an actual rotational speed of the turbine during control during a transient state An actual rotation speed detecting means for detecting the supply amount, a supply amount calculating means for calculating a necessary supply amount of an auxiliary substance required to increase the actual rotation speed to the target rotation speed, and Composed of auxiliary substances in main supply amount comprises a supply execution means for supplying to the exhaust passage upstream of the turbine.

  According to this configuration, in the transient state of the internal combustion engine, by supplying the minimum necessary auxiliary material upstream of the turbine, the work of the turbine is increased, and the supercharging pressure of the compressor is temporarily recovered. In addition to improving the transient response of the turbocharger and improving drivability, the increase in NOx, soot and unburned hydrocarbons contained in the exhaust gas can be prevented, and the target engine performance can be reduced. It can be demonstrated quickly.

  In addition, since the supply amount of auxiliary substances can be suppressed to the minimum necessary amount, the cost can be reduced and the influence on the aftertreatment device provided in the exhaust passage downstream from the turbine should be minimized. Can do.

  Furthermore, even when a vehicle equipped with an internal combustion engine with a supercharging assist system is suddenly changed due to an idling stop or the like, rapid control is possible. Can be used for starting and stopping the engine, and fuel consumption can be improved.

Further, in the supercharging assist system for the internal combustion engine, when the supplementary substance is gas when the supplementary substance is supplied to the exhaust passage, the constant pressure specific heat at the time of the supplementary substance gas is calculated as C. _pinj , constant pressure specific heat of exhaust gas C _pexh , auxiliary material temperature T _inj , exhaust gas temperature before passing through the turbine T _{exh_in} , mixed gas of exhaust gas and auxiliary material before passing through the turbine When the temperature is T _{mix_in} and the inflow amount of exhaust gas passing through the turbine is W _exh , the required supply amount W _injmin of the auxiliary substance passing through the turbine is

  When configured to calculate based on the above formulas (1) and (2), when the auxiliary substance is a gas when the auxiliary substance is supplied to the exhaust passage, the above formula (1) and ( 2) By using the formula, the required supply amount of the auxiliary substance can be calculated with higher accuracy.

In the supercharging assist system for an internal combustion engine, the supply amount calculating means may be configured such that when the auxiliary substance is supplied to the exhaust passage, the auxiliary substance is a liquid and the total amount of the auxiliary substance is not passed through the turbine. Is determined to evaporate, the constant pressure specific heat when the auxiliary substance is gas is C _pinj , the specific heat when the auxiliary substance is liquid is C _liq , the constant pressure specific heat of the exhaust gas is C _pexh , and the mixed gas of exhaust gas and auxiliary substance the constant pressure specific heat of C _Pmix, temperature T _inj of auxiliary substances, the boiling point T _inj [nu _ap auxiliary substances, temperature T _{Exh_in} exhaust gas before passing through the turbine, the mixed gas before passing through the turbine When the temperature is T _{mix_in} , the exhaust gas inflow amount passing through the turbine is W _exh , and the latent heat of vaporization of the auxiliary material is ΔH _inj ν _ap , the required supply amount W _injmin of the auxiliary material passing through the turbine is

  When configured to calculate based on the above equations (3) and (4), when the auxiliary material is liquid when supplying the auxiliary material to the exhaust passage, the latent heat of vaporization is considered and the above is considered. By using the equations (3) and (4), the required supply amount of the auxiliary substance can be calculated with higher accuracy.

  Further, in the supercharging assist system for an internal combustion engine, the actual rotational speed detected by the target rotational speed calculation means is detected by the atmospheric pressure detection means and the intake air temperature detection means provided in the apparatus including the internal combustion engine. When the correction is made based on the atmospheric pressure and the actual intake air temperature, the target rotational speed and the actual rotational speed are estimated accurately by correcting the detected values of sensors (atmospheric pressure detection means and intake air temperature detection means). Therefore, the required supply amount of the auxiliary substance can be calculated with higher accuracy.

  And the supercharging assistance method of the internal combustion engine of the present invention for achieving the above-described object is provided by the turbocharger of the turbocharger system in a transient state of the internal combustion engine provided with the turbocharger system. In a supercharging assist method for an internal combustion engine for supplying an auxiliary substance for increasing the rotation of the turbine to an exhaust passage upstream of a turbine, a target intake air flow rate to the compressor of the turbocharger after a transient state and the compressor The target rotational speed of the turbine is calculated based on the target supercharging pressure downstream of the turbine, and the actual rotational speed of the turbine at the time of control during the transient state is detected, and the actual rotational speed is increased to the target rotational speed. In this method, a necessary supply amount of the auxiliary material necessary for the calculation is calculated, and the auxiliary material is supplied to the exhaust passage on the upstream side of the turbine with the necessary supply amount.

Further, in the above-described supercharging assistance method for an internal combustion engine, when the auxiliary substance is a gas when supplying the auxiliary substance to the exhaust passage, the constant pressure specific heat at the time of the auxiliary substance gas is C _pinj and the constant pressure specific heat of the exhaust gas. C _pexh , the temperature of the auxiliary material T _inj , the temperature of the exhaust gas before passing through the turbine T _{exh_in} , the temperature of the mixed gas of the exhaust gas and auxiliary material before passing through the turbine T _{mix_in} , the turbine the inflow of the exhaust gas passing through when the W _exh to the required supply quantity W _Injmin auxiliary material passing through the turbine,

  It calculates based on said (1) Formula and (2) Formula.

Further, in the above-described supercharging assist method for an internal combustion engine, when the auxiliary substance is supplied to the exhaust passage, it is determined that the auxiliary substance is a liquid and the entire amount of the auxiliary substance evaporates before passing through the turbine. If the specific heat at constant pressure when gaseous auxiliary substances C _Pinj, the specific heat at the time of liquid C _liq auxiliary substances, the specific heat at constant pressure C _Pexh of exhaust gases, the specific heat at constant pressure of the mixed gas C _Pmix, the temperature of the auxiliary substances T _inj, the boiling point T _inj [nu _ap auxiliary substances, temperature T _{Exh_in} exhaust gas before passing through the turbine, the temperature of the T _{Mix_in} of the mixed gas before passing through the turbine, the exhaust gases passing through the turbine When the inflow amount is W _exh and the latent heat of vaporization of the auxiliary substance is ΔH _inj ν _ap , the necessary supply amount W _injmin of the auxiliary substance passing through the turbine is

  It calculates based on said (3) Formula and (4) Formula.

  In the supercharging assist method for the internal combustion engine, the target rotational speed and the actual rotational speed are corrected based on the actual atmospheric pressure and the actual intake air temperature.

  According to these methods, the same effects as those of the supercharging assist system for the internal combustion engine can be obtained.

  According to the supercharging assistance system and the supercharging assistance method of an internal combustion engine of the present invention, a work amount of the turbine is obtained by supplying a supplementary material with a minimum necessary supply amount upstream of the turbine in a transient state of the internal combustion engine. , And temporarily recovers the turbocharging pressure of the compressor, thereby improving the transient response of the turbocharger and improving the drivability, as well as NOx, Soot (煤) and The increase in unburned hydrocarbons can be prevented, and the target engine performance can be exhibited quickly.

  Further, since the supply amount of the auxiliary substance can be suppressed to the minimum necessary, the cost can be reduced, and the influence on the aftertreatment device provided in the exhaust passage downstream from the turbine can be reduced as much as possible. .

  Furthermore, even when a vehicle equipped with an internal combustion engine with a supercharging assist system is suddenly changed due to an idling stop or the like, rapid control is possible. It can be used even when starting and stopping the engine, and fuel consumption can be improved.

It is a figure which shows the structure of the supercharging assistance system of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows the structure of the control apparatus of the supercharging assistance system of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows an example of the control flow of the supercharging assistance method of the internal combustion engine of embodiment which concerns on this invention. It is a figure which shows an example of the substance supply amount calculation map of the supercharging assistance method of the internal combustion engine of embodiment which concerns on this invention.

  Hereinafter, an internal combustion engine supercharging assist system 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) 10 including an internal combustion engine supercharging assist system 1 according to an embodiment of the present invention includes an engine body 11, an intake passage 15, an exhaust passage 16, and an EGR passage 17. Yes. The engine body 11 is provided with a fuel injection device 12 (only one is shown in FIG. 1 for simplification) for each cylinder (cylinder), and intake air is connected to the connection port between the engine body 11 and the intake passage 15. An exhaust valve 14 is provided at the connection port between the engine body 11 and the exhaust passage 16.

  An intake passage 15 connected to the engine body 11 via an intake manifold (not shown) is provided with a compressor 20b, an intercooler 21, and an intake valve 22 of a turbocharger (turbo supercharger) 20 in order from the upstream side. ing. The exhaust passage 16 connected to the engine body 11 via an exhaust manifold (not shown) is provided with a turbine 20a of the turbocharger 20 and an aftertreatment device 23 in order from the upstream side. The EGR passage 17 is provided by connecting an exhaust passage 16 upstream of the turbine 20a and an intake passage 15 downstream of the compressor 20b, and an EGR cooler 24 and an EGR valve 25 are provided in this order from the upstream side. Yes.

  The intake air (fresh air) A introduced from the atmosphere is sent to the engine body 11 via the compressor 20b, the intercooler 21, and the intake valve 22, and is injected into each cylinder from the fuel injection device 12. And the fuel is burned to generate power in the engine body 11. Then, the exhaust gas G generated by this combustion is discharged to the exhaust passage 16, a part thereof is used as the EGR gas Ge in the EGR passage 17, and the remaining exhaust gas Go (= G-Ge) passes through the turbine 20a. The purified exhaust gas Gc is purified by the post-processing device 23 via the exhaust gas, and discharged to the atmosphere via a muffler (not shown).

  On the other hand, in the turbocharger 20 constituting the turbocharging system 20S, the turbine 20a is rotationally driven using the energy of the exhaust gas G, so that the compressor 20b directly connected to the turbine 20a via the connecting shaft 20c. Is driven and the intake air A is compressed. Therefore, by using this turbo-type supercharging system 20S, it is possible to increase the supercharging pressure P of the intake air A and increase the intake air flow rate F (not shown), so that the power generated in the engine body 11 is increased. be able to.

  However, in a vehicle equipped with the engine 10 equipped with the turbo-type supercharging system 20S, the supercharging pressure P of the intake air A increases to the target supercharging pressure in a transient state where the load of the engine 10 increases rapidly. There is a problem of a turbo lag that delays and the intake flow rate F is insufficient.

  Therefore, in the embodiment according to the present invention, the engine 10 is provided with a supercharging assist system 1 as shown in FIG. The supercharging assist system 1 includes an auxiliary substance storage tank 1a, a supply pump 1b, a heat exchanger 1c, a heater 1d, and an auxiliary substance injection device 1e. When the engine 10 is in a transient state, the turbocharging system 20S The auxiliary substance injection device 1e provided in the exhaust passage 16 upstream of the turbine 20a of the turbocharger 20 supplies an auxiliary substance M that increases the rotation of the turbine 20a, whereby the amount of gas passing through the turbine 20a. (Intake amount) is increased, the work amount of the turbine 20a is increased, and the rotational speed of the turbine 20a is increased. Here, when the engine 10 is in a transitional state, for example, in the case of an automobile, it means the operating state of the engine 10 when the driver depresses the accelerator pedal and the vehicle suddenly starts or accelerates.

  The auxiliary substance M may be any of gas, liquid, and solid as long as the rotation of the turbine 20a can be increased. However, it is preferable to use a substance having a large specific heat such as compressed air, exhaust gas, or water vapor. Further, the auxiliary material M is exhausted from the auxiliary material storage tank 1a via the supply pump 1b by the heat exchanger 1c so that the rotation of the turbine 20a can be efficiently increased in a small amount. Heat exchange with Go or EGR gas Ge or heating with a heater 1d is preferably performed, and the temperature is increased, and then supplied to the exhaust passage 16 upstream of the turbine 20a via the auxiliary material injection device 1e. However, before the auxiliary substance M is supplied to the exhaust passage 16, it is only necessary to heat the auxiliary substance M and raise the temperature, and the heat exchanger 1c and the heater 1d are not necessarily provided.

  The supercharging assistance system 1 includes a control device 41 that controls the supercharging assistance system 1 such as control of the supply amount of the auxiliary substance M. As shown in FIG. 1, the control device 41 includes a flow sensor 30, a pressure sensor 31, a rotation sensor 32, an exhaust gas temperature sensor 33, an auxiliary substance temperature sensor 34, an atmospheric pressure sensor 35, and an engine 10. Information such as the intake air temperature sensor 36 is input. Further, the control device 41 controls the supply amount of the auxiliary substance M by controlling the output of the supply pump 1b and the auxiliary substance injection device 1e based on the information of these various sensors.

  Further, the control device 41 controls the fuel injection of the fuel injection device 12 and the opening degree control of the EGR valve 25 based on information of various sensors provided in the engine 10 or various sensors provided in a device equipped with the engine 10. And the like, and incorporated in an overall system control device 40 that performs overall control of the engine 10 and overall control of the vehicle. In FIG. 1, an input signal to the control device 41 is indicated by a one-dot chain line, and output signals from the overall system control device 40 and the control device 41 are indicated by a two-dot chain line.

Here, the various sensors described above will be described. The flow sensor 30 is a sensor that is provided in the intake passage 15 upstream of the compressor 20b and detects the intake flow F to the compressor 20b of the turbocharger 20. The pressure sensor 31 is a sensor that is provided between the compressor 20b and the intercooler 21 and detects the supercharging pressure P of the intake air A after passing through the compressor 20b. When the pressure loss of the intercooler 21 or the intake valve 22 is calculated from the amount of intake air and the pressure after passing through the compressor 20b is estimated, the pressure sensor 31 may be installed on the downstream side of the intercooler 21 or the intake valve 22. The rotation sensor 32 is a sensor that is provided on the connecting shaft 20c of the turbocharger 20 and detects an actual rotation speed Na of the turbine 20a. The exhaust gas temperature sensor 33 is a sensor that is provided in the exhaust passage 16 upstream of the auxiliary substance injection device 1e and detects the temperature T _{exh_in} of the exhaust gas Go before passing through the turbine 20a. The auxiliary substance temperature sensor 34 is a sensor that is provided in the supply passage between the heater 1d and the auxiliary substance injection apparatus 1e and detects the temperature T _inj of the auxiliary substance M. The atmospheric pressure sensor 35 is a sensor that detects atmospheric pressure (actual atmospheric pressure) P ₀ . The intake air temperature sensor 36 is a sensor that detects the temperature T ₀ of the intake air flow rate F flowing into the intake passage 15 of the engine 10.

Then, in the supercharging assist system 1 for the engine 10 according to the present invention, the control device 41 that controls the supply amount of the auxiliary substance M takes in the air to the compressor 20b of the turbocharger 20 in the target state after the supercharging state is over. A target rotational speed calculation means 41a for calculating a target rotational speed Nr of the turbine 20a based on a target intake air flow rate F when A is supplied and a target supercharging pressure P of the intake air A downstream of the compressor 20b; The actual rotational speed detecting means 41b for detecting the actual rotational speed Na of the turbine 20a at the time of the control, and the necessary supply of the auxiliary material M necessary for increasing the actual rotational speed Na of the turbine 20a to the target rotational speed Nr of the turbine 20a a supply amount calculating means 41c for calculating the amount W _Injmin, auxiliary substances M required supply quantity W _Injmin amount and the exhaust passage 16 upstream of the turbine 20a Configured with a supply execution means 41d for feeding.

  The configuration of the control device 41 is simply shown in FIG. Further, the target intake air flow rate F and the target supercharging pressure P in the target state after the transient state are the engine rotation speed and load (or fuel injection amount) before the transient state, and the changed accelerator opening that is the start of the transient state. Etc., with reference to preset map data or the like.

  The target rotational speed of the compressor 20b is also the target rotational speed of the turbine 20a, but the rotational speed of the compressor 20b is determined by the supply flow rate and the supercharging pressure. The sensor 30 detects the intake flow rate F, the pressure sensor 31 detects the supercharging pressure P, the rotation sensor 32 detects the actual rotational speed Na, and maps the intake flow rate F and the actual rotational speed Na with respect to the supercharging pressure P. The target rotational speed Nr is calculated with respect to the target intake flow rate F and the target boost pressure P using the map data. Further, since the rotational speed is determined by the intake air flow rate and the pressure ratio before and after the compressor 20b, the target rotational speed calculation means 41a is configured so as to calculate the target rotational speed Nr from the target intake flow rate F and the pressure ratio Rp before and after the compressor 20b. May be configured. Since the actual rotational speed Na is represented by the intake flow rate F and the supercharging pressure P, the actual rotational speed Na may be estimated from values measured by the flow sensor 30 and the pressure sensor 31 without using the rotation sensor 32.

Further, the target rotational speed calculation means 41a detects the target rotational speed Nr by an atmospheric pressure sensor (atmospheric pressure detection means) 35 and an intake air temperature sensor 36 (intake air temperature detection means) provided in a device including the engine 10. When the correction is made based on the actual atmospheric pressure P ₀ and the actual intake air temperature T ₀ , the estimated accuracy of the target rotation speed Nr is obtained by correcting the detected values of the atmospheric pressure sensor 35 and the intake air temperature sensor 36 and the like. Therefore, the necessary supply amount W _injmin of the auxiliary substance M can be calculated with higher accuracy. When the actual rotational speed Na is estimated from the intake air flow rate F and the supercharging pressure P, the actual rotational speed Na is corrected by the detected values of the atmospheric pressure sensor 35 and the intake air temperature sensor 36 in the same manner as the target rotational speed Nr. The calculation accuracy of the rotation speed Na can be improved.

Then, the supply amount calculation means 41a of the control device 41, when supplying the auxiliary substance M to the exhaust passage 16, if the auxiliary substance M is a gas, C _{pinj is} the constant pressure specific heat at the time of the auxiliary substance M gas, and the exhaust gas The constant pressure specific heat of Go is C _pexh , the temperature of the auxiliary material M is T _inj , the temperature of the exhaust gas Go before passing through the turbine 20 a is T _{exh_in} , and the mixed gas of the exhaust gas Go and auxiliary material M before passing through the turbine 20 a the temperature of _gmix T mix_in, the inflow of exhaust gas Go to passing through the turbine 20a when the W _exh, at supply amount calculating means 41c, the required supply quantity W _Injmin auxiliary substances M passing through the turbine 20a, It is comprised so that it may calculate based on the following (1) Formula and (2) Formula.

The unit of each specific heat (C _pinj , C _pexh ) is [J / K · g], the unit of each temperature (T _inj , T _{exh_in} , T _{mix_in} ) is [K], and each flow rate (W _exh , W _injmin ). The unit of is [kg / s].

Accordingly, when the auxiliary substance M is a gas when the auxiliary substance M is supplied to the exhaust passage 16, the required supply amount W _injmin of the auxiliary substance M is obtained by using the above formulas (1) and (2). Can be calculated with high accuracy.

The lower limit value W _injmin of the necessary supply amount of the auxiliary substance M is calculated by using the above equations (1) and (2). The upper limit value W _injmax of the necessary supply amount of the auxiliary substance M is calculated in advance. For example, the lower limit value W _injmin is set to 10 times the lower limit value W _injmin or the like.

Further, when the supply amount calculation means 41a of the control device 41 determines that the auxiliary substance M is liquid and the entire amount of the auxiliary substance M evaporates when supplying the auxiliary substance M to the exhaust passage 16, the auxiliary substance M M of gas at the constant pressure specific heat of C _Pinj, specific heat of C _liq when liquid auxiliary substances M, the specific heat at constant pressure of the exhaust gas Go C _Pexh, the constant pressure specific heat of the gas mixture gmix C _Pmix, the temperature of the auxiliary material M T _inj , the boiling point of the auxiliary substance M is T _inj ν _ap , the temperature of the exhaust gas Go before passing through the turbine 20a is T _{exh_in} , the temperature of the mixed gas Gmix before passing through the turbine 20a is T _{mix_in} , and passes through the turbine 20a When the inflow amount of the exhaust gas Go is W _exh and the latent heat of vaporization of the auxiliary substance M is ΔH _inj ν _ap , the required supply amount W _injmin of the auxiliary substance M passing through the turbine 20a is calculated by the supply amount calculating means 41c as _follows: (3) and (4 ) Based on the formula.

Here, the unit of each specific heat (C _pinj , C _pexh , C _liq , C _pmix ) is [J / K · g], and the unit of each temperature (T _inj , T _{exh_in} , T _{mix_in} , T _inj ν _ap ) is [ K], the unit of latent heat of evaporation (ΔH _inj ν _ap ) is [J / K], and the unit of each flow rate (W _exh , W _injmin ) is [kg / s].

Thus, when the auxiliary substance M is supplied to the exhaust passage 16 and the auxiliary substance M is a liquid, the above equations (3) and (4) are used in consideration of the latent heat of evaporation ΔH _inj ν _ap. Thus, the required supply amount _Winjmin of the auxiliary substance M can be calculated with higher accuracy.

The lower limit value W _injmin of the required supply amount of the auxiliary substance M is calculated by using the above equations (3) and (4), but the upper limit value W _injmax of the required supply amount of the auxiliary substance M is calculated in advance. For example, the lower limit value W _injmin is set to 10 times the lower limit value W _injmin or the like.

  Further, the above formulas (1) and (3) are the same calculation formula, but when the auxiliary substance M is supplied to the exhaust passage 16, the formula used when the auxiliary substance M is a gas, and the auxiliary substance M In order to distinguish clearly from the formula used when is a liquid, different formulas are used.

Required supply quantity W _Injmin calculation for mixing gas Gmix temperature T _{Mix_in} a for calculating the above required (2) and (4), since it is necessary to value required supply quantity _W injmin, (1 ) And (2), or (3) and (4) are iteratively calculated several times to obtain a convergent solution, whereby the required supply amount W _injmin is calculated.

Regarding the determination of whether or not the total amount of the auxiliary substance M evaporates, at least the temperature T _{exh_in} of the exhaust gas Go detected by the exhaust gas temperature sensor 33 is higher than the boiling point T _inj ν _ap of the auxiliary substance M. In addition, the temperature T _{mix_in} of the mixed gas G _mix of the exhaust gas Go and the evaporated auxiliary substance M needs to be _{equal to} or higher than the boiling point T _inj ν _ap of the auxiliary substance M. In other words, heat from the boiling point T _inj [nu _ap with the exhaust gas Go to a temperature T _{Exh_in} is, the heat quantity for raising the temperature of the auxiliary material M from the temperature T _inj auxiliary substances M to the boiling point T _inj [nu _ap, auxiliary substances It needs to be larger than the sum of heat amounts due to latent heat of vaporization required for evaporation of M.

Accordingly, whether or not the entire amount of the auxiliary substance M is evaporated is determined based on the temperature T _{exh_in} of the exhaust gas Go before passing through the turbine 20a, the flow rate of the exhaust gas Go, and the boiling point T _inj ν _ap of the auxiliary substance M. Calculate the amount of heat from the boiling point T _inj ν _{ap of the} exhaust gas Go to the temperature T _{exh_in,} and the amount of heat is the amount of heat supplied from the auxiliary material M and the temperature T _inj to the boiling point T _inj ν _ap and the auxiliary material. It can be judged by whether or not it is larger than the sum of heat amounts required for evaporation of M.

The flow rate of the exhaust gas Go can be calculated by the intake flow rate F and the fuel injection amount, and the temperature T _{exh_in} of the exhaust gas Go can be _detected by the exhaust gas temperature sensor 33 and calculated by referring to preset map data or the like. Or you may calculate from the signal and fuel injection amount of various sensors. Further, as the supply amount of the auxiliary substance M, the necessary supply amount W _injmin can be used, but a judgment supply amount W _c set in advance for simplification of calculation can be used, and the temperature T _{inj of the} auxiliary substance M can be used. Can be detected by the auxiliary substance temperature sensor 34.

  Next, the supercharging assistance method for the internal combustion engine in the supercharging assistance system 1 for the internal combustion engine of the above embodiment will be described with reference to the control flow of FIG. The control flow in FIG. 3 assumes an automobile equipped with the engine 10, and when it is determined that a transient state such as when the vehicle starts or accelerates, that is, when an accelerator or the like is depressed and a transient state of the engine 10 occurs. Starting from the advanced control flow, the control of the control flow of FIG. 3 is performed, and when the engine 10 shifts from the transient state to the steady state, the process returns to the advanced control flow. When it is determined that the next transient state occurs, it is called from the advanced control flow, and is shown to be repeatedly executed during the transient state of the engine 10.

  When the control flow of FIG. 3 is called from an advanced control flow and started, it is determined in step S11 whether or not the engine 10 is in a transient state. This determination can be made based on whether the engine rotational speed is changing or whether the required output by the accelerator is in a transient state.

If it is determined in step S11 that the engine 10 is not in a transient state (NO), the process goes to return to end the present control flow and return to the advanced control flow. On the other hand, if the engine 10 is in a transient state (YES), the process proceeds to step S12, where the turbine 20a is based on the intake air flow rate F to the compressor 20b of the turbocharger 20 and the supercharging pressure P of the intake air A downstream of the compressor 20b. Target rotational speed Nr is calculated, and the process proceeds to step S13. Here, the target rotational speed Nr of the turbine 20a is based on the actual atmospheric pressure P ₀ and the actual intake air temperature T ₀ detected by the atmospheric pressure sensor 35, the intake air temperature sensor 36, and the like provided in the vehicle including the engine 10. If corrected, the estimation accuracy of the target rotational speed Nr can be improved, and the necessary supply amount _Winjmin of the auxiliary substance M can be calculated more accurately.

In step S13, the actual rotational speed Na of the turbine 20a when the engine 10 is in a transient state is detected. When the actual rotational speed Na is estimated from the values measured by the flow sensor 30 and the pressure sensor 31 without using the rotation sensor 32, if it is corrected based on the actual atmospheric pressure P ₀ and the actual intake air temperature T ₀ as described above, The estimation accuracy of the rotation speed Na can be improved. In the next step S14, it is determined whether or not the auxiliary substance M needs to be supplied because there is a difference equal to or greater than a value Ng preset by experiment or the like between the target rotational speed Nr and the actual rotational speed Na. This determination is made based on whether or not Nr-Na ≧ Ng is satisfied. When it is determined that Nr-Na ≧ Ng is not satisfied (NO), it is determined that the supply of the auxiliary substance M is not necessary, and the process goes to return. When it is determined that Nr-Na ≧ Ng is established (YES), it is assumed that the auxiliary substance M needs to be supplied, and the process proceeds to step S15.

In step S15, the required supply amount _Winjmin of the auxiliary substance M necessary for increasing the actual rotational speed Na of the turbine 20a to the target rotational speed Nr of the turbine 20a is calculated, and the process proceeds to step S16.

In this step S15, when the auxiliary substance M is a gas at the time of supplying the auxiliary substance M to the exhaust passage 16, the constant pressure specific heat at the time of the gas of the auxiliary substance M is C _pinj , and the constant pressure specific heat of the exhaust gas Go is C _pexh , the temperature of the auxiliary material M T _inj, the temperature of the exhaust gas Go before passing through the turbine _20a T exh_in, the temperature of the mixed gas Gmix before the exhaust gas Go and auxiliary substances M passing through the turbine _20a T mix_in, turbine The required supply amount W _injmin of the auxiliary substance M passing through the turbine 20a is calculated based on the following equations (1) and (2), where W _exh is the inflow amount of the exhaust gas Go passing through 20a.

Thereby, the required supply amount _Winjmin of the auxiliary substance M can be calculated more accurately.

In step S15, when it is determined that the auxiliary substance M is liquid when the auxiliary substance M is supplied to the exhaust passage 16, and the total amount of the auxiliary substance M evaporates, the constant pressure specific heat when the auxiliary substance M is gas is determined. the C _Pinj, specific heat of C _liq when liquid auxiliary substances M, the specific heat at constant pressure C _Pexh of exhaust gas Go, the constant pressure specific heat C _Pmix mixed gas gmix, temperature T _inj auxiliary substances M, the boiling point of the auxiliary substances M T _inj ν _ap , the temperature of the exhaust gas Go before passing through the turbine 20a is T _{exh_in} , the temperature of the mixed gas Go before passing through the turbine 20a is T _{mix_in} , and the inflow amount of the exhaust gas Go passing through the turbine 20a is W _exh , when the latent heat of vaporization of the auxiliary substance M is ΔH _inj ν _ap , the required supply amount W _injmin of the auxiliary substance M passing through the turbine 20a is calculated based on the following equations (3) and (4). .

Thereby, the required supply amount _Winjmin of the auxiliary substance M can be calculated more accurately.

In step S16, the supply pump 1b is driven to pump the auxiliary material M stored in the auxiliary material storage tank 1a to the auxiliary material injection device 1e, and the supply amount of the auxiliary material M is supplied from the auxiliary material injection device 1e. The _power is supplied to the exhaust passage 16 upstream of the turbine 20a by W _inj , and after a preset control time has elapsed, the process returns to step S11.

FIG. 4 shows an example of a reference map used for calculating the supply amount W _inj of the auxiliary substance M. When the supply amount is increased so that the difference between the target rotation speed Nr and the actual rotation speed Na increases, the actual rotation speed Na can be increased to the target rotation speed Nr more quickly. The reference map may be constant regardless of the difference between the target rotational speed Nr and the actual rotational speed Na as a multiple of the required supply amount W _injmin , or the amount of change that increases the supply amount _Winj may not be constant.

  And in step S11 which returned, step S11-step S16 are repeated, but when it determines with the engine 10 not being in a transient state by step S11 (NO), it determines with the supply of the auxiliary | assistant substance M not being required by step S14. In the case (NO), the supply of the auxiliary substance M is stopped, the return is made, the present control flow is terminated, and the upper control flow is returned.

  When the engine 10 stops in the middle of this control flow, an interrupt is generated and the process returns to end this control flow, returns to the advanced control flow, and when the engine 10 stops operating, FIG. The control flow ends with the end of this advanced control flow.

  According to the supercharging assistance system 1 and the control method thereof for the engine 10 having the above-described configuration, when the engine 10 is in a transient state, the minimum amount of auxiliary material M is supplied upstream of the turbine 20a, so that the work load of the turbine 20a is increased. , And temporarily recovers the supercharging pressure P of the compressor 20b, thereby improving the transient response of the turbocharger 20 and improving the drivability, as well as NOx and soot (煤) contained in the exhaust gas Go. In addition, an increase in unburned hydrocarbons can be prevented, and the target engine performance can be exhibited quickly.

  Further, since the supply amount of the auxiliary substance M can be suppressed to the minimum necessary amount, the cost can be reduced, and in addition, the influence on the aftertreatment device 23 provided in the exhaust passage 16 on the downstream side of the turbine 20a is affected. It can be reduced as much as possible.

  Further, assuming an automobile equipped with the engine 10 with the supercharging assist system, even when the vehicle is suddenly changed due to an idling stop or the like, rapid control is possible. It can be used not only for acceleration but also for starting and stopping the engine 10, and fuel efficiency can be improved.

Hereinafter, the derivation of the above equations (1) to (4) will be described. Generally, the axial torque Tq _turbine of the turbine 20a of the turbocharger 20 is calculated by using the following formulas (5) and (6).

Here, C _{p is} the constant pressure specific heat of the gas, W is the mass flow rate passing through the turbine 20a, N is the rotational speed of the connecting shaft 20c, T _{in is} the temperature at the inlet of the turbine 20a, T _{out is} the temperature at the outlet of the turbine 20a, The pressure at the inlet of the turbine 20a is P _in , the pressure at the outlet of the turbine 20a is P _out , η _turbine is the turbine efficiency, and κ is the specific heat ratio.

Using the above equation (5), the shaft torque Tq _{w / ogas} of the turbine 20a when the auxiliary material M is not supplied is the following equation (7), and the shaft torque Tq of the turbine 20a when the auxiliary material M is supplied _{w / gas} is expressed by the following equation (8).

Here, the constant pressure specific heat of the exhaust gas Go is C _pexh , the constant pressure specific heat of the mixed gas Gmix is C _pmix , the inflow amount of the exhaust gas Go passing through the turbine 20a is W _exh , and the temperature of the exhaust gas Go before passing through the turbine 20a the _T exh_in, the temperature of the exhaust gas Go after passing through the turbine _20a T exh_out, and the temperature T _{Mix_in} of the mixed gas Gmix before passing through the turbine 20a, the temperature of the mixed gas Go after passing through the turbine 20a and the T _{MIX_OUT} .

In order to increase the actual rotation speed Na of the turbine 20a and increase the supercharging pressure P of the compressor 20b from the state where the auxiliary material M is not supplied, the shaft torque Tq _{w /} of the turbine 20a when the auxiliary material M is not supplied. The shaft torque Tq _{w / gas} of the turbine 20a after supplying the auxiliary substance M may be increased from _ogas . That is, the right side of the above equation (7) <the right side of the above equation (8) may be satisfied. By organizing this inequality, the following equation (9) is obtained.

  Here, at the instant when the auxiliary substance M is supplied upstream of the turbine 20a, since the turbocharger 20 has inertial force, the actual rotational speed Na does not change immediately, and the efficiency of the turbine 20a is immediately after the supply. When the amount of the auxiliary substance M to be supplied is small relative to the flow rate of the exhaust gas Go, the pressure before and after the turbine 20a does not change so much. Further, since the influence of the specific heat ratio κ is small, the above equations (1) and (3) can be derived by simplifying the above equation (9).

On the other hand, when the auxiliary substance M is a gas when the auxiliary substance M is supplied to the exhaust passage 16, the temperature of the mixed gas Gmix with the exhaust gas Go is assumed to preserve the enthalpy, as shown in the following equation (10). It is expressed.

  The above equation (2) can be derived by rearranging the above equation (10).

Further, when the auxiliary substance M is a liquid when the auxiliary substance M is supplied to the exhaust passage 16, assuming that all the injected liquid is a gas, the temperature of the mixed gas Gmix with the exhaust gas Go is conserved. As shown in the following equation (11).

  By arranging the above equation (11), the above equation (4) can be derived.

Since the following equation (12) can be derived from the above equations (1) and (2), the auxiliary material M is gas when the control device 41 supplies the auxiliary material M to the exhaust passage 16. In this case, the control may be performed so as to calculate the required supply amount W _inj of the auxiliary substance M passing through the turbine 20a based on the equation (12). Further, when it is necessary to control with higher accuracy, the control may be performed so as to calculate the required supply amount W _injmin of the auxiliary substance M passing through the turbine 20a by the equation (9).

DESCRIPTION OF SYMBOLS 1 Supercharging assistance system 1a Auxiliary substance storage tank 1b Supply pump 1c Heat exchanger 1d Heater 1e Auxiliary substance injection apparatus 10 Engine (internal combustion engine)
DESCRIPTION OF SYMBOLS 11 Engine main body 12 Fuel injection apparatus 13 Intake valve 14 Exhaust valve 15 Intake passage 16 Exhaust passage 17 EGR passage 20S Turbo supercharging system 20 Turbocharger (turbo supercharger)
20a Turbine 20b Compressor 20c Connecting shaft 21 Intercooler 22 Intake valve 23 After-treatment device 24 EGR cooler 25 EGR valve 30 Flow rate sensor 31 Pressure sensor 32 Rotation sensor 33 Exhaust gas temperature sensor 34 Auxiliary substance temperature sensor 35 Atmospheric pressure sensor 36 Intake temperature sensor 40 overall system control device 41 control unit 41a target rotational speed calculation means 41b actual rotational speed detecting means 41c supply amount calculating means 41d when the liquid supply means of implementation M auxiliary substances C _Pinj isobaric specific heat C _liq auxiliary substances when gaseous auxiliary substances Specific heat of C _pexh constant pressure specific heat of exhaust gas T _inj auxiliary material temperature T _inj ν _ap boiling point of auxiliary material T _{exh_in} temperature of exhaust gas before passing through turbine T _{mix_in} mixing of exhaust gas and auxiliary material before passing through turbine temperature RT _{Mix_in} exhaust gas temperature region [Delta] H _inj [nu _ap auxiliary gas Maximum supply amount of the auxiliary material passing through the required supply quantity W _Injmax turbine auxiliary material passing through the supply amount W _Injmin turbine auxiliary material passing through the inflow W _inj turbine exhaust gas passing through the latent heat of vaporization W _exh turbine quality value a suction set target rotational speed Ng advance of the actual rotational speed Nr turbine W _c determined for supply amount Na turbine (fresh air)
P Intake supercharging pressure F Intake flow rate G, Go Exhaust gas Gmix Mixed gas Gc Purified exhaust gas Ge EGR gas P ₀ Actual atmospheric pressure T ₀ Intake temperature

Claims (8)

An internal combustion engine that supplies an auxiliary substance that increases the rotation of the turbine to an exhaust passage upstream of the turbine of the turbocharger of the turbocharger in a transient state of the internal combustion engine provided with the turbocharger In the supercharging assistance system of
A control device that controls the supply amount of auxiliary substances
Target rotational speed calculation means for calculating a target rotational speed of the turbine based on a target intake air flow rate to the compressor of the turbocharger after the transient state and a target supercharging pressure downstream of the compressor;
An actual rotational speed detecting means for detecting an actual rotational speed of the turbine during control during a transient state;
A supply amount calculating means for calculating a necessary supply amount of an auxiliary substance required to increase the actual rotation speed to the target rotation speed;
A supercharging assist system for an internal combustion engine, comprising supply execution means for supplying an auxiliary substance to the exhaust passage upstream of the turbine at the required supply amount. The supply amount calculating means is
When the auxiliary substance is a gas when supplying the auxiliary substance to the exhaust passage,
The constant pressure specific heat at the time of gas of the auxiliary substance is C _pinj , the constant pressure specific heat of the exhaust gas is C _pexh , the temperature of the auxiliary substance is T _inj , the temperature of the exhaust gas before passing through the turbine is T _{exh_in} , and before passing through the turbine When the temperature of the mixed gas of the exhaust gas and the auxiliary substance is T _{mix_in} and the inflow amount of the exhaust gas passing through the turbine is W _exh , the required supply amount W _injmin of the auxiliary substance passing through the turbine is

2. The supercharging assist system for an internal combustion engine according to claim 1, wherein the supercharging assist system is configured to calculate based on the equations (1) and (2). The supply amount calculating means is
When the auxiliary substance is supplied to the exhaust passage and it is determined that the auxiliary substance is a liquid and the total amount of the auxiliary substance evaporates before passing through the turbine,
C _{pinj is} the constant pressure specific heat of the auxiliary substance when it is gas, C _{liq is} the specific heat of the auxiliary substance when it is liquid, C _{pexh is} the constant pressure specific heat of the exhaust gas, C _{pmix is} the constant pressure specific heat of the mixed gas of the exhaust gas and auxiliary substance, The temperature is T _inj , the boiling point of the auxiliary material is T _inj ν _ap , the temperature of the exhaust gas before passing through the turbine is T _{exh_in} , the temperature of the mixed gas before passing through the turbine is T _{mix_in} , and passes through the turbine When the exhaust gas inflow is W _exh and the latent heat of vaporization of the auxiliary material is ΔH _inj ν _ap , the required supply amount W _injmin of the auxiliary material passing through the turbine is

The supercharging assist system for an internal combustion engine according to claim 1 or 2, wherein the supercharging assist system is configured to calculate based on the equations (3) and (4). The target rotation speed calculation means
The said target rotational speed is comprised so that it may correct | amend based on the actual atmospheric pressure detected by the atmospheric pressure detection means provided in the vehicle provided with the said internal combustion engine. A supercharging assist system for an internal combustion engine according to item. An internal combustion engine that supplies an auxiliary substance that increases the rotation of the turbine to an exhaust passage upstream of the turbine of the turbocharger of the turbocharger in a transient state of the internal combustion engine provided with the turbocharger In the supercharging assistance method of
Calculating a target rotational speed of the turbine based on a target intake air flow rate to the compressor of the turbocharger after the transient state and a target supercharging pressure downstream of the compressor;
Detecting the actual rotational speed of the turbine during control during the transient state;
Calculating the required supply of auxiliary substances required to increase the actual rotational speed to the target rotational speed;
A supercharging assist method for an internal combustion engine, wherein an auxiliary substance is supplied to the exhaust passage upstream of the turbine in the required supply amount. When the auxiliary substance is a gas when supplying the auxiliary substance to the exhaust passage,
The constant pressure specific heat at the time of gas of the auxiliary substance is C _pinj , the constant pressure specific heat of the exhaust gas is C _pexh , the temperature of the auxiliary substance is T _inj , the temperature of the exhaust gas before passing through the turbine is T _{exh_in} , and before passing through the turbine When the temperature of the mixed gas of the exhaust gas and the auxiliary substance is T _{mix_in} and the inflow amount of the exhaust gas passing through the turbine is W _exh , the required supply amount W _injmin of the auxiliary substance passing through the turbine is

6. The supercharging assist method for an internal combustion engine according to claim 5, wherein the calculation is based on the equations (1) and (2). When the auxiliary substance is supplied to the exhaust passage and it is determined that the auxiliary substance is a liquid and the total amount of the auxiliary substance evaporates before passing through the turbine,
C _{pinj is} the constant pressure specific heat of the auxiliary substance when it is gas, C _{liq is} the specific heat of the auxiliary substance when it is liquid, C _{pexh is} the constant pressure specific heat of the exhaust gas, C _{pmix is} the constant pressure specific heat of the mixed gas of the exhaust gas and auxiliary substance, The temperature is T _inj , the boiling point of the auxiliary material is T _inj ν _ap , the temperature of the exhaust gas before passing through the turbine is T _{exh_in} , the temperature of the mixed gas before passing through the turbine is T _{mix_in} , and passes through the turbine When the exhaust gas inflow is W _exh and the latent heat of vaporization of the auxiliary material is ΔH _inj ν _ap , the required supply amount W _injmin of the auxiliary material passing through the turbine is

The supercharging assistance method for an internal combustion engine according to claim 5 or 6, wherein the calculation is based on the expressions (3) and (4).   The supercharging assist method for an internal combustion engine according to any one of claims 5 to 7, wherein the target rotational speed is corrected based on an actual atmospheric pressure.

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