JP6300085B2 - Internal combustion engine system - Google Patents

Description

  The present invention relates to an internal combustion engine system. More specifically, the present invention relates to an internal combustion engine system that can suppress or prevent carbon deposition in a reforming catalyst disposed in an exhaust gas circulation passage.

2. Description of the Related Art Conventionally, there has been proposed a control apparatus for an internal combustion engine that suppresses the occurrence of coking and improves the fuel efficiency by improving the generation efficiency of reformed gas.
The control device for the internal combustion engine is generated by a fuel reforming unit that generates reformer gas by heating and reforming a mixed gas composed of a fuel and a gas containing oxygen, and the fuel reforming unit. The reformer gas supply means for supplying the reformer gas to the intake passage of the internal combustion engine, the humidity detection means for detecting the humidity, and the mixing ratio of the gas containing fuel and oxygen is changed based on the detection result of the humidity detection means. Mixing ratio changing means (see Patent Document 1).

JP 2006-291757 A

  By the way, depending on the situation of the operation of the internal combustion engine, unburned hydrocarbons may exist even if it is set to be stoichiometric combustion. In the control device for an internal combustion engine described in Patent Document 1, the three-way catalyst Part of the exhaust gas is introduced into the recirculation passage from the exhaust pipe downstream of the exhaust gas, and the unburned hydrocarbons discharged are purified by the three-way catalyst before being introduced into the recirculation passage. There is no configuration in which the provided reforming catalyst is exposed to exhaust gas containing unburned hydrocarbons.

  When the reforming catalyst may be exposed to exhaust gas containing unburned hydrocarbons, the humidity of the exhaust gas, the rotational speed of the internal combustion engine, the load of the internal combustion engine, the exhaust gas temperature, etc. Even if the mixing ratio of the fuel and the gas containing oxygen is changed based on this, there is a problem that the deposition of carbon in the reforming catalyst cannot be suppressed or prevented.

  The present invention has been made in view of such problems of the prior art. An object of the present invention is to provide an internal combustion engine system that can suppress or prevent the deposition of carbon in a reforming catalyst disposed in an exhaust gas circulation passage.

  The inventors of the present invention have made extensive studies in order to achieve the above object. As a result, the amount of unburned hydrocarbons in the combustion chamber is estimated, and based on the estimated amount of unburned hydrocarbons, the supply amount of reforming fuel supplied by the fuel supply means is controlled. The present inventors have found that the object can be achieved and have completed the present invention.

That is, an internal combustion engine system according to the present invention includes an internal combustion engine having a combustion chamber, an intake passage connected to the combustion chamber, an exhaust passage connected to the combustion chamber, an exhaust passage, and an exhaust gas A three-way catalyst that purifies the exhaust gas, an exhaust circulation passage that connects the exhaust passage and the intake passage upstream of the exhaust gas flow from the position of the three-way catalyst, and reforming in the exhaust circulation passage A fuel supply means for supplying fuel for use, and a reformer that is disposed in the exhaust circulation passage and generates a reformed gas containing hydrogen by a reforming reaction using the exhaust gas in the exhaust circulation passage and the reforming fuel Estimating the amount of unburned hydrocarbons in the combustion chamber and the catalyst, and controlling the amount of reforming fuel supplied by the fuel supply means based on the estimated amount of unburned hydrocarbons and it means, and unburned hydrocarbons quantity estimation control unit, estimated the catalytic reaction increases the temperature of the three-way catalyst Storing the map data of the estimated temperature previously obtained by the temperature estimating means, the estimated unburned hydrocarbon quantity previously obtained by the unburned hydrocarbon quantity estimation control means, and the supply amount of reforming fuel And a supply amount of the reforming fuel supplied by the fuel supply means based on the result obtained by the arithmetic processing means from the map data and the estimated temperature estimated by the temperature estimation means. The estimated temperature acquired in advance in the map data and the estimated unburned hydrocarbon amount acquired in advance are expressed by the following equation (1) estimated unburned hydrocarbon amount (%) = ΔT / T _af × 100. 1) (In formula (1), ΔT represents an estimated temperature estimated by the temperature estimating means, and T _af represents the adiabatic flame temperature of the fuel) .

According to the present invention, an internal combustion engine having a combustion chamber, an intake passage connected to the combustion chamber, an exhaust passage connected to the combustion chamber, and an exhaust passage disposed in the exhaust passage to purify exhaust gas. The reforming fuel is supplied into the exhaust gas circulation channel, the exhaust gas circulation channel connecting the exhaust gas flow channel upstream of the exhaust gas flow from the position where the three-way catalyst is disposed, and the intake gas flow channel. A fuel supply means, a reforming catalyst that is disposed in the exhaust circulation passage and generates a reformed gas containing hydrogen by a reforming reaction using the exhaust gas in the exhaust circulation passage and the reforming fuel, and combustion An unburned hydrocarbon amount estimation control means for estimating an unburned hydrocarbon amount in the chamber and controlling a supply amount of reforming fuel supplied by the fuel supply means based on the estimated unburned hydrocarbon amount; includes, unburned hydrocarbon amount estimation control means includes temperature estimating means for estimating the catalytic reaction increases the temperature of the three-way catalyst, Calculation processing means for storing map data of the estimated temperature acquired in advance by the degree estimation means, the estimated unburned hydrocarbon quantity acquired in advance by the unburned hydrocarbon quantity estimation control means, and the supply amount of reforming fuel And controlling the supply amount of the reforming fuel supplied by the fuel supply means based on the result obtained by the arithmetic processing means from the map data and the estimated temperature estimated by the temperature estimation means, and obtaining in advance in the map data The estimated temperature obtained and the estimated unburned hydrocarbon amount acquired in advance are expressed by the following equation (1) estimated unburned hydrocarbon amount (%) = ΔT / T _af × 100 (1) (equation (1 ), ΔT is the estimated temperature estimated by the temperature estimating means, and T _af represents the adiabatic flame temperature of the fuel .
Therefore, it is possible to provide an internal combustion engine system that can suppress or prevent carbon deposition in the reforming catalyst disposed in the exhaust circulation passage.

FIG. 1 is an explanatory diagram illustrating an outline of the internal combustion engine system according to the first embodiment. FIG. 2 is an explanatory diagram showing an outline of the internal combustion engine system of the second embodiment. FIG. 3 is an explanatory diagram showing an outline of the internal combustion engine system of the third embodiment. FIG. 4 is a graph illustrating the effect of the present invention.

  Hereinafter, an internal combustion engine system according to an embodiment of the present invention will be described in detail.

(First embodiment)
The internal combustion engine system according to the first embodiment is disposed in an internal combustion engine having a combustion chamber, an intake passage connected to the combustion chamber, an exhaust passage connected to the combustion chamber, and an exhaust passage. A three-way catalyst for purifying the exhaust gas, an exhaust circulation passage connecting the exhaust passage and the intake passage upstream of the exhaust gas flow from the position of the three-way catalyst, and an exhaust circulation passage A fuel supply means for supplying the reforming fuel and a reformed gas that is disposed in the exhaust circulation passage and that uses hydrogen and the reforming fuel in the exhaust circulation passage to generate reformed gas containing hydrogen. The amount of unburned hydrocarbons for estimating the amount of unburned hydrocarbons in the reforming catalyst and the combustion chamber and controlling the amount of reforming fuel supplied by the fuel supply means based on the estimated amount of unburned hydrocarbons And an estimation control means.

  With such a configuration, the amount of reforming fuel supplied can be controlled based on the estimated amount of unburned hydrocarbons in the fuel chamber. Carbon deposition in the catalyst can be suppressed or prevented. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved. In addition, since the performance degradation of the reforming catalyst can be suppressed or prevented, there is also an advantage that the frequency of the regeneration process that leads to a reduction in fuel consumption can be reduced.

In the internal combustion engine system according to the present embodiment, for example, the unburned hydrocarbon amount estimation control unit supplies the estimated unburned hydrocarbon amount and the reforming fuel acquired in advance by the unburned hydrocarbon amount estimation control unit. And a fuel supply unit based on a result obtained by the arithmetic processing unit from the map data and the unburned hydrocarbon amount estimated by the unburned hydrocarbon amount estimation control unit. It is preferable to have a configuration for controlling the amount of reforming fuel supplied by the means.
With this configuration, it is possible to estimate the amount of unburned hydrocarbons based on map data acquired in advance, so it is arranged in the exhaust circulation channel without adding parts such as sensors. It is possible to suppress or prevent the deposition of carbon in the reformed catalyst. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved. In addition, since the performance degradation of the reforming catalyst can be suppressed or prevented, there is also an advantage that the frequency of the regeneration process that leads to a reduction in fuel consumption can be reduced.

In the internal combustion engine system of the present embodiment, for example, when the unburned hydrocarbon amount estimation control means controls the supply amount of reforming fuel supplied by the fuel supply means, the fuel supply means supplies It is preferable to have a configuration that controls to reduce the amount of quality fuel supplied.
By setting it as such a structure, precipitation of the carbon content in the reforming catalyst arrange | positioned at the exhaust gas circulation flow path can be suppressed thru | or prevented. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved. In addition, since the performance degradation of the reforming catalyst can be suppressed or prevented, there is also an advantage that the frequency of the regeneration process that leads to a reduction in fuel consumption can be reduced.

Further, in the present embodiment, for example, when the unburned hydrocarbon amount estimation control means estimates the unburned hydrocarbon amount in the combustion chamber, it estimates the water vapor amount based on the estimated unburned hydrocarbon amount. It is preferable that the supply amount of the reforming fuel supplied by the fuel supply means is controlled based on the estimated water vapor amount.
By adopting such a configuration, it is possible to perform control such as reducing the supply amount of reforming fuel in consideration of the amount (concentration) of water vapor in the exhaust gas. The deposition of carbon in the reforming catalyst can be suppressed or prevented. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved. In addition, since the performance degradation of the reforming catalyst can be suppressed or prevented, there is also an advantage that the frequency of the regeneration process that leads to a reduction in fuel consumption can be reduced.
That is, in particular, whether or not carbon is deposited depends on the temperature and the amount of water vapor in the exhaust gas, so that the steam carbon ratio (S / C) allowed at each temperature is improved. It is preferable to reduce the supply of quality fuel.
And the presence of unburned hydrocarbons means that the amount of water vapor in the exhaust gas is also smaller than when no unburned hydrocarbons are present.
Therefore, the supply amount of the reforming fuel is set so that the S / C or more allowed at each temperature is considered in consideration of the amount of water vapor in the exhaust gas that is decreasing due to the presence of unburned hydrocarbons. Is preferably reduced.

(Second Embodiment)
In the internal combustion engine system according to the second embodiment, the unburned hydrocarbon amount estimation control means includes a temperature estimation means for estimating the catalytic reaction rising temperature of the three-way catalyst, an estimated temperature previously acquired by the temperature estimation means, Computational processing means for storing map data of the estimated unburned hydrocarbon quantity and the supply amount of reforming fuel acquired in advance by the fuel hydrocarbon quantity estimation control means, and is estimated by the map data and the temperature estimation means. This is different from the first embodiment described above in that the supply amount of the reforming fuel supplied by the fuel supply means is controlled based on the result obtained by the arithmetic processing means from the estimated temperature.

  With such a configuration, the amount of unburned hydrocarbon in the fuel chamber is estimated based on the catalytic reaction rising temperature of the three-way catalyst, and the reforming is performed based on the estimated amount of unburned hydrocarbon in the combustion chamber. Since the fuel supply amount can be controlled, it is possible to suppress or prevent carbon deposition in the reforming catalyst disposed in the exhaust circulation flow path by estimating the catalyst reaction rising temperature. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved. In addition, since the performance degradation of the reforming catalyst can be suppressed or prevented, there is also an advantage that the frequency of the regeneration process that leads to a reduction in fuel consumption can be reduced.

  In the internal combustion engine system of the present embodiment, for example, the estimated temperature acquired in advance in the map data and the estimated unburned hydrocarbon amount acquired in advance have a relationship represented by the following equation (1). It is preferable to have a configuration.

Estimated unburned hydrocarbon amount (%) = ΔT / T _af × 100 (1)
(In the formula (1), ΔT represents the estimated temperature estimated by the temperature estimating means, and T _af represents the adiabatic flame temperature of the fuel.)

  As described above, when the estimated temperature acquired in advance in the map data and the estimated unburned hydrocarbon amount acquired in advance have a relationship represented by the above formula (1), the unburned hydrocarbon amount. Can be estimated by a simple equation.

(Third embodiment)
In the internal combustion engine system according to the third embodiment, the unburned hydrocarbon amount estimation control means includes an oxygen concentration sensor provided at the outlet of the combustion chamber, a detected oxygen concentration acquired in advance by the oxygen concentration sensor, and an unburned hydrocarbon. And a calculation processing means for storing map data of the estimated unburned hydrocarbon amount and the supply amount of reforming fuel obtained in advance by the hydrogen amount estimation control means, and detection detected by the map data and the oxygen concentration sensor. It differs from the first or second embodiment described above in that it has a configuration for controlling the amount of reforming fuel supplied by the fuel supply means based on the result obtained by the arithmetic processing means from the oxygen concentration. .

  With such a configuration, the amount of unburned hydrocarbon in the fuel chamber is estimated based on the oxygen concentration at the outlet of the combustion chamber, and the reforming amount is determined based on the estimated amount of unburned hydrocarbon in the combustion chamber. Since the amount of fuel supply can be controlled, it is possible to suppress or prevent the deposition of carbon in the reforming catalyst disposed in the exhaust circulation passage by detecting the oxygen concentration at the outlet of the combustion chamber. . Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved. In addition, since the performance degradation of the reforming catalyst can be suppressed or prevented, there is also an advantage that the frequency of the regeneration process that leads to a reduction in fuel consumption can be reduced.

  Hereinafter, an internal combustion engine system of the present invention will be described in detail based on some embodiments with reference to the drawings.

Example 1
FIG. 1 is an explanatory diagram illustrating an outline of the internal combustion engine system according to the first embodiment. As shown in FIG. 1, an internal combustion engine system 1A of the present example includes a four-cycle engine 10 that is an example of a reciprocating internal combustion engine, an intake passage (hereinafter referred to as “intake pipe”) 20, and an exhaust passage. (Hereinafter referred to as “exhaust pipe”) 30, three-way catalyst 40, exhaust circulation passage (hereinafter referred to as “EGR (Exhaust Gas Recirculation) pipe”) 50, fuel supply means 60, reforming catalyst 70, And a controller 80.

  The intake pipe 20 is connected to the intake port 11 a of the combustion chamber 11 of the engine 10, and the exhaust pipe 30 is connected to the exhaust port 11 b of the combustion chamber 11 of the engine 10. The three-way catalyst 40 is disposed in the exhaust pipe 30 and purifies the exhaust gas. Further, the EGR pipe 50 connects the exhaust pipe 30 and the intake pipe 20 on the upstream side with respect to the exhaust gas flow from the position where the three-way catalyst 40 is disposed. The EGR pipe 50 is exhausted from the exhaust pipe 30 to the intake pipe 20. Is for partly dividing, that is, refluxing. The fuel supply means 60 supplies reforming fuel into the EGR pipe 50. Further, the reforming catalyst 70 is disposed in the EGR pipe 50, and generates reformed gas containing hydrogen by a reforming reaction using the exhaust gas in the EGR pipe 50 and the reforming fuel. The controller 80 functions as unburned hydrocarbon amount estimation control means, estimates the unburned hydrocarbon amount in the combustion chamber 11, and based on the estimated unburned hydrocarbon amount, supplies fuel. The supply amount of the reforming fuel supplied by 60 is controlled.

  Further, the engine 10 includes an intake valve 11c that opens and closes the intake port 11a, an exhaust valve 11d that opens and closes the exhaust port 11b, a piston 11e that reciprocates in the combustion chamber 11, and an air-fuel mixture in the combustion chamber 11. A spark plug 11f that displaces electric sparks is disposed.

  Further, the intake pipe 20 is provided with a main fuel supply means 21 in the vicinity of the intake port 11a, and the air flowing in the intake pipe 20 toward the combustion chamber 11 on the upstream side of the main fuel supply means 21 in the intake direction. An intake control valve 22 for controlling the amount of air is further provided. Here, the main fuel supply means 21 has a function of injecting main fuel into the combustion chamber 11 or the intake pipe 20.

  The exhaust pipe 30 is provided with an exhaust control valve 31 for controlling the exhaust amount of the exhaust gas flowing through the exhaust pipe 30.

  Further, the three-way catalyst 40 is provided with a catalyst bed temperature sensor 32 for detecting the catalyst bed temperature.

  The EGR pipe 50 includes a fuel supply means 60 for supplying reforming fuel into the EGR in a direction (indicated by an arrow α in the figure) from the upstream side to the downstream side with respect to the exhaust gas flow. A quality catalyst 70, an EGR cooler 51, and an EGR valve 52 are sequentially arranged. The reforming fuel may be the same as or different from the main fuel.

  Here, the reforming catalyst 70 generates reformed gas containing hydrogen by a reforming reaction using the exhaust gas in the EGR pipe 50 and the reforming fuel. Typically, it has a function of reacting the reforming fuel and at least a part of the exhaust, and reforming the fuel to generate a reformed gas containing hydrogen, such as a noble metal, more specifically May include rhodium. Normally, since exhaust contains heat and moisture, the reforming catalyst promotes at least one of a thermal decomposition reaction, a steam reforming reaction, and a water gas shift reaction by adding a reforming fuel, and hydrogen. The reformed gas containing is generated.

  The EGR cooler 51 has a function of cooling exhaust gas and reformed gas, and the EGR valve 52 has a function of controlling the flow rate of exhaust gas and reformed gas.

  Further, the controller 80 is not particularly limited as long as it can function as an unburned hydrocarbon amount estimation control unit, and includes, for example, a central processing unit (CPU) that is an example of the processing unit 81. . For example, the controller 80 includes the main fuel supply means 21, intake control valve 22, exhaust control valve 31, catalyst bed temperature sensor 32, fuel supply means 60, EGR valve 52, intake valve 11c, exhaust valve 11d, piston It is connected to a control unit (not shown) such as 11e, inputs / outputs signals related to control, and operates them appropriately by executing a predetermined program.

  The EGR pipe in which the reforming catalyst is disposed is supplied with a part of the exhaust gas that has been stoichiometrically burned in the combustion chamber by controlling the exhaust control valve based on the EGR rate and the EGR gas temperature. Exhaust gas containing unburned hydrocarbons may be supplied, and in particular, when reforming fuel is supplied without considering the amount of unburned hydrocarbons, reforming containing hydrogen by reforming reaction from the reforming fuel. While a quality gas is obtained, carbon may be generated (deposited) on the reforming catalyst from an excess of the total amount of reforming fuel and unburned hydrocarbon.

  Therefore, in the internal combustion engine system of this example, for example, the controller that functions as the unburned hydrocarbon amount estimation control means estimates the unburned hydrocarbon amount in the combustion chamber, and based on the estimated unburned hydrocarbon amount. By performing control such as reducing the supply amount of reforming fuel supplied by the fuel supply means, it is possible to supply reforming fuel in consideration of the amount of unburned hydrocarbons to the reforming catalyst, Precipitation of carbon in the reforming catalyst disposed in the EGR pipe can be suppressed or prevented. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine system can be improved.

  Further, in the internal combustion engine system of this example, for example, the controller that functions as the unburned hydrocarbon amount estimation control means is the estimated unburned hydrocarbon amount acquired in advance by the controller that functions as the unburned hydrocarbon amount estimation control means. Arithmetic processing means for storing map data of the fuel and the supply amount of reformed fuel, and arithmetic processing means from the map data and the unburned hydrocarbon amount estimated by the controller functioning as the unburned hydrocarbon amount estimation control means Based on the results obtained by the above, by controlling the reduction of the supply amount of the reforming fuel supplied by the fuel supply means, the unburned catalyst is not burned to the reforming catalyst without adding components such as sensors. The reforming fuel can be supplied in consideration of the amount of hydrocarbons, and the carbon deposition in the reforming catalyst installed in the EGR pipe is suppressed or prevented. It is possible. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine system can be improved.

(Example 2)
FIG. 2 is an explanatory diagram showing an outline of the internal combustion engine system of the second embodiment. In addition, about the structure same as Example 1, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 2, in the internal combustion engine system 1B of this example, the controller 80 functioning as the unburned hydrocarbon amount estimation control means has temperature estimation means for estimating the catalytic reaction rising temperature of the three-way catalyst 40, and temperature estimation. Arithmetic processing means 81 for storing map data of the estimated temperature acquired in advance by the means, the estimated unburned hydrocarbon quantity acquired in advance by the unburned hydrocarbon quantity estimation control means, and the supply amount of reforming fuel In addition, the supply amount of the reforming fuel supplied by the fuel supply unit 60 may be controlled based on the result obtained by the arithmetic processing unit 81 from the map data and the estimated temperature estimated by the temperature estimation unit. This is different from the internal combustion engine system of the first embodiment. Note that the temperature estimation means includes a catalyst bed temperature sensor 32 that detects the catalyst bed temperature of the three-way catalyst 40, a catalyst inlet temperature sensor 33 that detects the inlet temperature of the three-way catalyst 40, and the arithmetic processing means 81. Demonstrate its function. That is, in the three-way catalyst, if there is unburned hydrocarbon and oxygen in the exhaust gas, the catalyst bed temperature rises due to the oxidation reaction, so that the temperature detected by the catalyst bed temperature sensor 32 is detected by the catalyst inlet temperature sensor 33. The arithmetic processing means calculates the temperature difference, and thus the catalyst reaction rising temperature can be estimated. Since the catalyst reaction rising temperature varies depending on the amount of unburned hydrocarbon, the amount of unburned hydrocarbon can be estimated.

Therefore, in the internal combustion engine system of this example, the amount of unburned hydrocarbons in the fuel chamber is estimated based on the catalyst reaction rising temperature of the three-way catalyst, and based on the estimated amount of unburned hydrocarbons in the combustion chamber, Since control such as reducing the supply amount of reforming fuel can be performed, the precipitation of carbon in the reforming catalyst disposed in the exhaust circulation channel is suppressed or prevented by estimating the catalyst reaction rising temperature. can do. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved.
The catalyst inlet temperature may be a value estimated according to the engine operating conditions such as the engine speed and load. Further, an estimated value may be used for the catalyst bed temperature.

  For example, the amount of unburned hydrocarbons can be estimated from the estimated temperature ΔT estimated from the temperature difference between the catalyst bed temperature and the catalyst inlet temperature by the following equation (1).

Estimated unburned hydrocarbon amount (%) = ΔT / T _af × 100 (1)
(In the formula (1), ΔT represents the estimated temperature estimated by the temperature estimating means, and T _af represents the adiabatic flame temperature of the fuel.)

  The adiabatic flame temperature of the fuel is determined by the temperature and specific heat of each fuel. If a fuel having an adiabatic flame temperature of 2500 ° C. is used and ΔT is 100 ° C., the amount of unburned hydrocarbons is 4% can be estimated.

(Example 3)
FIG. 3 is an explanatory diagram showing an outline of the internal combustion engine system of the third embodiment. In addition, about the structure same as Example 1 or Example 2, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 3, in the internal combustion engine system 1 </ b> C of this example, a controller 80 that functions as an unburned hydrocarbon amount estimation control unit includes an oxygen concentration sensor 34 provided at the outlet of the combustion chamber 11, and an oxygen concentration sensor 34. And an arithmetic processing means 81 for storing map data of the detected oxygen concentration acquired in advance and the estimated unburned hydrocarbon amount acquired in advance by the unburned hydrocarbon amount estimation control means and the supply amount of reforming fuel. In addition, the supply amount of the reforming fuel supplied by the fuel supply unit 60 is controlled based on the result obtained by the arithmetic processing unit 81 from the map data and the detected oxygen concentration detected by the oxygen concentration sensor 34. This is different from the first or second embodiment described above.

With such a configuration, the amount of unburned hydrocarbon in the fuel chamber is estimated based on the oxygen concentration at the outlet of the combustion chamber, and the reforming amount is determined based on the estimated amount of unburned hydrocarbon in the combustion chamber. Since control such as reducing the amount of fuel supply can be performed, the precipitation of carbon in the reforming catalyst disposed in the exhaust circulation channel is suppressed or prevented by detecting the oxygen concentration at the outlet of the combustion chamber. can do. Further, this can suppress or prevent the performance degradation of the reforming catalyst, and furthermore, the desired reformed gas can be obtained, so that the fuel efficiency of the internal combustion engine can be improved.
For example, an oxygen sensor or an A / F sensor may be applied as the oxygen concentration sensor. In addition, as for the oxygen concentration, a value estimated based on an operation state or the like without using the sensor may be used.

  For example, in the case of an internal combustion engine having an unburned hydrocarbon amount of 4% when the oxygen concentration at the outlet of the combustion chamber is 0.6%, the unburned hydrocarbon amount is estimated by the following equation (2). can do.

Estimated unburned hydrocarbon amount (%) = 4 / 0.6 × C _{O2 (OUT)} (2)
(In Formula (2), _{CO 2 (OUT)} indicates the oxygen concentration at the outlet of the combustion chamber.)

  Although it is necessary to grasp in advance the characteristics of the internal combustion engine to be used, when an oxygen sensor or an A / F sensor is provided, it is preferable because no additional components are required.

FIG. 4 is a graph showing the effect of the present invention. Specifically, the unburned hydrocarbon amount estimation control means estimates the unburned hydrocarbon amount in the combustion chamber, and based on the estimated unburned hydrocarbon amount, the reforming fuel supplied by the fuel supply means An example of the effect when the supply amount is controlled is shown. The horizontal axis represents temperature (Temperature), and the vertical axis represents steam carbon ratio (S / C).
If the amount of unburned hydrocarbons is not taken into consideration, that is, if it is not controlled, the reforming fuel supplied to the reforming catalyst becomes excessive, and the operation in the hatched portion of the region where carbon is deposited is performed. It becomes.
On the other hand, when taking into account the amount of unburned hydrocarbons, that is, when controlling to reduce the supply amount of reforming fuel, operation in the shaded area can be avoided and operation in a region where carbon content does not precipitate It becomes.
Further, since it is possible to suppress or prevent the carbon deposition in the reforming catalyst disposed in the exhaust circulation channel, it is possible to suppress or prevent the performance degradation of the reforming catalyst, and further, the desired reforming Since gas can be obtained, the fuel consumption of the internal combustion engine can be improved.

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

  That is, the configuration described in the internal combustion engine system of each embodiment and each example described above is not limited to each embodiment or example. For example, each configuration described in each embodiment or example is described above. Combinations other than the embodiment and examples can be made, and details of the configuration can be changed.

  Further, for example, in each of the above-described embodiments, a reciprocating internal combustion engine is exemplified as the internal combustion engine. However, the present invention is not limited to this, and can be applied to a conventionally known internal combustion engine.

1A, 1B, 1C Internal combustion engine system 10 Engine 11 Combustion chamber 11a Intake port 11b Exhaust port 12c Intake valve 13d Exhaust valve 11e Piston 11f Spark plug 20 Intake pipe 21 Main fuel supply means 22 Intake control valve 30 Exhaust pipe 31 Exhaust control valve 32 Catalyst bed temperature sensor 33 Catalyst inlet temperature sensor 34 Oxygen concentration sensor 40 Three-way catalyst 50 EGR pipe 51 EGR cooler 52 EGR valve 60 Combustion supply means 70 Reforming catalyst 80 Controller 81 Arithmetic processing means

Claims (5)

An internal combustion engine having a combustion chamber;
An intake passage connected to the combustion chamber;
An exhaust passage connected to the combustion chamber;
A three-way catalyst disposed in the exhaust passage and purifying exhaust gas;
An exhaust circulation passage connecting the exhaust passage upstream of the three-way catalyst with respect to the exhaust gas flow and the intake passage;
Fuel supply means for supplying reforming fuel into the exhaust circulation passage;
A reforming catalyst that is disposed in the exhaust circulation channel and generates a reformed gas containing hydrogen by a reforming reaction using the exhaust gas in the exhaust circulation channel and the reforming fuel;
Unburned hydrocarbon amount estimation control for estimating the amount of unburned hydrocarbon in the combustion chamber and controlling the amount of reforming fuel supplied by the fuel supply means based on the estimated amount of unburned hydrocarbon and means, the Bei example,
The unburned hydrocarbon amount estimation control means includes a temperature estimation means for estimating the catalyst reaction rising temperature of the three-way catalyst, an estimated temperature acquired in advance by the temperature estimation means, and the unburned hydrocarbon amount estimation control means. Computation processing means for storing map data of the estimated unburned hydrocarbon amount acquired in advance and the supply amount of the reforming fuel, and the estimated temperature estimated by the temperature estimation means Based on the result obtained by the arithmetic processing means, the supply amount of the reforming fuel supplied by the fuel supply means is controlled,
The estimated temperature acquired in advance in the map data and the estimated unburned hydrocarbon amount acquired in advance are expressed by the following equation (1).
Estimated unburned hydrocarbon amount (%) = ΔT / T _af × 100 (1)
An internal combustion engine system having a relationship expressed by (in formula (1), ΔT is an estimated temperature estimated by the temperature estimating means, and T _af is an adiabatic flame temperature of the fuel). . Arithmetic processing means in which the unburned hydrocarbon amount estimation control means stores map data of the estimated unburned hydrocarbon quantity acquired in advance by the unburned hydrocarbon quantity estimation control means and the supply amount of the reforming fuel And the reforming supplied by the fuel supply means based on the result obtained by the arithmetic processing means from the map data and the unburned hydrocarbon quantity estimated by the unburned hydrocarbon quantity estimation control means. The internal combustion engine system according to claim 1, wherein a supply amount of the engine fuel is controlled. The unburned hydrocarbon amount estimation control means is previously acquired by the oxygen concentration sensor provided at the outlet of the combustion chamber, the detected oxygen concentration previously acquired by the oxygen concentration sensor, and the unburned hydrocarbon amount estimation control means. Arithmetic processing means for storing map data of the estimated unburned hydrocarbon amount and the supply amount of the reforming fuel, and the map data and the detected oxygen concentration detected by the oxygen concentration sensor The internal combustion engine system according to claim 1 or 2 , wherein the supply amount of the reforming fuel supplied by the fuel supply means is controlled based on a result obtained by the arithmetic processing means. When the unburned hydrocarbon amount estimation control means controls the supply amount of the reforming fuel supplied by the fuel supply means, the supply amount of the reforming fuel supplied by the fuel supply means is reduced. The internal combustion engine system according to any one of claims 1 to 3 . When the unburned hydrocarbon amount estimation control means estimates the unburned hydrocarbon amount in the combustion chamber, the unburned hydrocarbon amount is estimated based on the estimated unburned hydrocarbon amount, and based on the estimated steam amount. The internal combustion engine system according to any one of claims 1 to 4, wherein a supply amount of the reforming fuel supplied by the fuel supply means is controlled.

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