JP2001241364A - Internal combustion engine with fuel reforming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a good reforming condition and to realize high heat efficiency when a reformer 8 is arranged in an exhaust passage 7. SOLUTION: The internal combustion engine is provided with a bypass passage 18 bypassing a reformer 8 in an exhaust passage 7 and a change-over valve 19 capable of changing over an exhaust flow passage between a side of the reformer 8 and a side of the bypass passage 18. By estimating a recoverable quantity Qe of an exhaust heat quantity to the reformer 8, when Qe is not greater than 0, a supply quantity of fuel, water and air to the reformer 8 is controlled by a reforming raw material flow controller 15 so that while an exhausted gas is guided to the side of the bypass passage 18, a heating value obtained by partial oxidation reaction between the fuel and the air in the reformer 8, is equal to an endothermic quantity obtained by vapor reforming reacting between the fuel and vapor. When Qe is beyond 0, a supply quantity of the fuel, the water, and the air to the reformer 8 is controlled such that while an exhausted gas is guided to the reformer 8, the ratio of the vapor reforming reaction to the partial oxidation reaction is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine equipped with a fuel reformer having a reformer for reforming a hydrocarbon-based fuel with a reforming catalyst and supplying a reformed gas to the engine. The present invention relates to a technique for maintaining a reforming state well and achieving high system efficiency.

[0002]

2. Description of the Related Art Conventionally, a steam-based reforming reaction between a hydrocarbon fuel such as gasoline, light oil, and methanol and steam in a high-temperature atmosphere has been carried out to produce hydrogen, carbon monoxide, methane, lower hydrocarbons, and oxygenated materials. It has been proposed to use such a gaseous fuel and supply the reformed gas to the engine to operate the engine, suppress harmful exhaust components from the engine, and improve the thermal efficiency of the engine.

On the other hand, since the steam reforming reaction is an endothermic reaction, it is necessary to supply heat to the reforming reaction field by some means in order to maintain a high temperature atmosphere. As such means, an electric heater is used, the calorie of the exhaust gas of the engine is recovered, and a combustion burner is separately provided.

In Japanese Patent Application Laid-Open No. 50-75602, a hydrocarbon-based fuel and air are reacted by a catalyst to generate a high-temperature product gas, which flows into a fuel reforming catalyst layer. By doing so, it has been proposed to use the heat as a heat source for the steam reforming reaction to start and maintain the reaction.

That is, a first reaction layer between fuel and air and a second reaction layer between fuel and water vapor are arranged in an exhaust passage of an engine, and when the exhaust temperature is sufficiently high, only the fuel and water vapor are discharged. 2 is supplied to the reaction layer to perform only the steam reforming reaction.
The high-temperature product gas is supplied to the reaction layer and introduced into the second reaction layer together with the fuel and the steam, and is used as a heat source for supplying the heat required for the steam reforming reaction.

[0006]

However, in the prior art described in the above publication, a reformer including a first reaction layer of fuel and air and a second reaction layer of fuel and steam is provided in an exhaust passage of an engine. When the exhaust gas temperature is low, part of the heat generated by the reaction between the fuel and air is taken by the exhaust gas. The amount of heat generated by the exothermic reaction is required, and the amount of heat generated by the fuel is wasted, so that there is a problem that the thermal efficiency as a whole system is reduced.

The present invention has been made in view of such conventional problems, and has a reformer for reforming a hydrocarbon-based fuel with a reforming catalyst, and supplies a reformed gas to an engine. In an internal combustion engine equipped with a reformer in the exhaust passage of the engine, by controlling the flow of exhaust gas according to the state of the engine and the reformer, the overall thermal efficiency of the system is improved. And the fuel, water,
An object is to realize clean fuel reforming with high thermal efficiency over a wide operating range by controlling the amount of air collectively.

[0008]

According to the first aspect of the present invention, there is provided a reformer for reforming a hydrocarbon-based fuel with a reforming catalyst to supply a reformed gas to an engine. An internal combustion engine with a reforming device, wherein the reformer is disposed in an exhaust passage of the engine, wherein a bypass passage connecting the reformer upstream and downstream of the exhaust passage and bypassing the reformer is provided. A switching valve capable of switching the flow path of the exhaust gas between the reformer side and the bypass passage side, and guiding the exhaust gas to the reformer side when the reformer can recover the calorific value of the exhaust gas. Switching control means for controlling the switching valve so as to guide exhaust gas to the bypass passage side when recovery is not possible.

The invention according to claim 2 is an internal combustion engine with a fuel reformer, which has a reformer for reforming hydrocarbon-based fuel with a reforming catalyst and supplies reformed gas to the engine. ,
In a case where the reformer is disposed in the exhaust passage of the engine, a bypass passage connecting the reformer upstream and downstream of the exhaust passage and bypassing the reformer, A switching valve that can be switched to a bypass passage side, an exhaust calorie recoverable amount estimating means for estimating a recoverable amount of exhaust calorie to the reformer, and the switch valve in accordance with the recoverable amount of exhaust calorie. And switching control means for controlling.

According to a third aspect of the present invention, in the second aspect of the invention, the switching control means controls the exhaust gas to be guided to the bypass passage when the recoverable amount of the exhaust heat is 0 or less. It is characterized by.

According to a fourth aspect of the present invention, in the third aspect of the invention, the switching control means controls the exhaust gas to be guided to the reformer when the recoverable amount of the exhaust heat exceeds 0. It is characterized by the following.

According to the invention of claim 5, in claim 3 or 4,
In the invention according to the above, when the recoverable amount of the exhaust heat is 0 or less, the amount of heat generated by the partial oxidation reaction between the fuel and air in the reformer and the amount of heat absorbed by the steam reforming reaction between the fuel and steam are reduced. And a reforming raw material control means for controlling the supply amounts of fuel, water and air to the reformer in the equal direction.

In the invention according to claim 6, in the invention according to claim 3, 4, or 5, when the recoverable amount of the exhaust heat exceeds 0, it is compared with when the recoverable amount of the exhaust heat is 0 or less. A reforming raw material that controls the supply of fuel, water and air to the reformer so as to increase the ratio of the steam and reforming reaction of fuel and steam with respect to the partial oxidation reaction of fuel and air in the reformer A control means is provided.

In the invention according to claim 7, in the invention according to claim 6, the reforming raw material control means reduces the supply amount of air to the fuel in order to increase the ratio of the steam reforming reaction to the partial oxidation reaction. And increasing the supply of water.

In the invention according to claim 8, in the invention according to claims 2 to 7, the exhaust heat calorie recoverable amount estimating means is based on at least a parameter related to the working gas amount of the engine and an exhaust gas temperature. And estimating a recoverable amount of exhaust heat to the reformer.

According to a ninth aspect of the present invention, in the second aspect of the present invention, the exhaust heat calorie recoverable amount estimating means learns the exhaust calorie recoverable amount based on a temperature change rate in the reformer. It is characterized by correction.

[0017]

According to the first aspect of the present invention, the bypass passage for bypassing the reformer and the switching valve are provided, and when the reformer can recover the exhaust heat, the exhaust gas is sent to the reformer side. When the reformer cannot recover the calorific value of the exhaust gas, the exhaust gas is guided to the bypass passage side, so when the exhaust gas temperature is low, the calorie required by the reformer is taken away by the exhaust gas, lowering the thermal efficiency. Can be prevented, and the thermal efficiency can be improved.

According to the second aspect of the present invention, while providing a bypass passage for bypassing the reformer and a switching valve, the amount of exhaust heat that can be recovered to the reformer is estimated, and this exhaust heat is recovered. Since the switching valve is controlled according to the possible amount, the heat efficiency can be improved by controlling the flow of the exhaust based on the recoverable amount of the exhaust heat.

According to the third aspect of the present invention, when the recoverable amount of the exhaust heat is equal to or less than 0, the exhaust gas is controlled to be guided to the bypass passage side. An effect is obtained that the heat efficiency can be reliably prevented from being reduced by the exhaust gas.

According to the fourth aspect of the invention, when the recoverable amount of exhaust heat exceeds 0, the exhaust gas is controlled to be guided to the reformer side, so that the exhaust heat can be recovered even a little. In some cases, this can be used to improve thermal efficiency.

According to the fifth aspect of the present invention, the partial oxidation of fuel and air in the reformer is performed on the premise that the exhaust gas is guided to the bypass passage when the recoverable amount of exhaust heat is 0 or less. Since the amount of fuel, water, and air supplied to the reformer is controlled so that the calorific value of the reaction and the heat absorption by the steam reforming reaction between the fuel and steam are substantially equal, external heat Independent operation can be performed without supplying the power.

According to the sixth aspect of the present invention, when the recoverable amount of the exhaust heat is less than 0, the exhaust gas is guided to the reformer when the recoverable amount of the exhaust heat exceeds 0. The amount of fuel, water and air supplied to the reformer is controlled so as to increase the ratio of the steam and reforming reaction of fuel and steam with respect to the partial oxidation reaction of fuel and air in the reformer. With this configuration, by increasing the rate of the steam reforming reaction, a reformed gas having a high calorific value can be obtained, and highly efficient operation can be performed.

According to the seventh aspect of the present invention, in order to increase the ratio of the steam reforming reaction to the partial oxidation reaction, the supply amount of air to the fuel is reduced and the supply amount of water is increased, so that the steam reforming is performed. Therefore, the reforming gas having a high calorific value can be obtained.

According to the eighth aspect of the present invention, the recoverable amount of the exhaust heat to the reformer is estimated based on the working gas amount of the engine and the exhaust temperature, so that a simple and sufficient estimation can be performed. Accuracy can be obtained.

According to the ninth aspect of the present invention, since the temperature inside the reformer changes due to the estimation error, the recoverable amount of the exhaust heat can be learned and corrected by the change rate of the temperature. The estimation accuracy can be improved.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of an internal combustion engine with a fuel reformer showing one embodiment of the present invention.

An air cleaner 3 is provided at an upstream end of an intake passage 2 of an internal combustion engine (engine) 1, and a throttle that is mechanically interlocked with an accelerator pedal 4 or driven by a motor based on its opening degree is provided downstream thereof. A valve 5 is provided, and a gas fuel injection valve 6 as a reformed gas supply means is provided downstream of the throttle valve 5.

In the middle of the exhaust passage 7 of the engine 1, a reformer 8 for performing fuel reforming is provided. Hydrocarbon fuel represented by gasoline, which is a raw fuel to be reformed, is supplied from a fuel tank 9 via a fuel pump 10, water is supplied from a water tank 11 via a water pump 12, and air is supplied from
Air pump 1 from air passage 13 branched from intake passage 2
4, is sent to the reforming raw material flow controller 15.

The reforming raw material flow controller 15 controls the flow rates of fuel, water and air, and sends them to the vaporizer 16. The vaporization mixer 16 is supplied with heat from the reformed gas generated in the reformer 8 or another heat source via a heat exchanger (not shown) to vaporize fuel and water and preheat air. While mixing the three fluids, the mixed three fluids are sent to the reformer 8.

The reformer 8 has a partial oxidation reaction layer 8A on the upstream side filled with a reforming catalyst for a partial oxidation reaction, and a downstream side filled with a reforming catalyst for a steam reforming reaction. As a structure having the layer 8B, heat exchange between heat generated by the partial oxidation reaction and heat absorption by the steam reforming reaction can be performed without loss. Of course, the steam reforming reaction and the partial oxidation reaction may be performed in the same reaction layer.

Accordingly, the mixture of the three fluids sent to the reformer 8 is reformed in accordance with the temperature of the reformer 8 and the mixing ratio of the three fluids, and hydrogen, carbon monoxide, methane, and lower It is reformed into a reformed gas such as hydrocarbon.

The temperature of the reformed gas generated in the reformer 8 is reduced by heat exchange with fuel, water and air before reforming, if necessary, in the reformed gas supply passage 17. The gas is sent to the gas fuel injection valve 6 while temporarily storing it in a storage tank not to prevent supply fluctuation. Then, the fuel is injected from the gas fuel injection valve 6 into the intake passage 2 of the engine 1 to supply the fuel.
Driving is performed.

Here, a bypass passage 18 that connects the upstream side and the downstream side of the reformer 8 of the exhaust passage 7 and bypasses the reformer 8 is provided.
A switching valve 19 that closes one of the reformer 8 side (main exhaust gas passage side) and the bypass passage 18 side and switches the exhaust gas flow path to either the reformer 8 side or the bypass passage 18 side.
Is provided. In the figure, reference numeral 20 denotes a catalytic converter for purifying exhaust gas.

The switching valve 19 and the reforming material flow rate controller 15 in addition to the gas fuel injection valve 6 are controlled by a control unit 21. The control unit 21 includes a crank angle sensor 22 for detecting the engine speed Ne, The accelerator opening sensor 23 for detecting the accelerator opening APO, the throttle sensor 24 for detecting the throttle opening TVO, the water temperature sensor 25 for detecting the engine cooling water temperature Tw, and the exhaust gas temperature Tex on the upstream side of the reformer 8. Signals are input from an exhaust temperature sensor 26 for detecting, a reforming temperature sensor 27 for detecting the temperature Tr in the reformer 8, and the like.

Next, the control in the present invention will be described. The steam reforming reaction of hydrocarbon fuel is generally represented by the following equation. _{C m H n + mH 2 O} → (m + n / 2) H 2 + mCO ··· (1) At the same _{time, 3H 2 + CO → CH 4} + H 2 O ··· (2) 2H 2 + 2CO → CH 4 + CO 2 ··· A reaction such as (3) is also performed.

When the reforming atmosphere is maintained at a high temperature,
The reaction (1) is mainly performed, and as shown in FIG. 2, the concentrations of hydrogen and carbon monoxide in the reformed gas increase. At a low temperature, the ratio of the reactions (2) and (3) increases, the concentrations of hydrogen and carbon monoxide in the reformed gas decrease, and conversely, the concentrations of methane and water increase.

The reaction (1) is an endothermic reaction, and it is necessary to apply heat by some means to maintain the reaction. On the other hand, since the reaction (1) is an endothermic reaction, there is an advantage that the calorific value of the gas after reforming is greater than the calorific value of the hydrocarbon fuel before reforming.

On the other hand, the hydrocarbon fuel and the air cause a partial oxidation reaction substantially in the following equation. C _m H _n + (m / 2) O ₂ → (n / 2) H ₂ + mCO (4) This reaction is an exothermic reaction, and the gas after reforming is contrary to the reaction of (1). Has a lower calorific value than the hydrocarbon fuel before reforming.

FIG. 3 shows that the amount of water and the amount of air to be introduced into the reformer are changed so that the temperature (reforming temperature) in the reformer can be maintained at a desired temperature Tr0. The ratio of the calorific value of the subsequent gas to the calorific value of the hydrocarbon fuel supplied to the reformer (calorific value ratio = reformed gas calorific value / raw fuel calorific value) is shown.

As can be seen from FIG. 3, the amount of water is increased,
As the amount of air is reduced, in other words, the rate of the steam reforming reaction is increased, and as the rate of the partial oxidation reaction is reduced, the calorific value of the reformed gas is increased. This means that in the reformed gas system that supplies the reformed gas to the engine, the amount of the hydrocarbon fuel required to generate the same engine output is small.

On the other hand, FIG. 4 shows the amount of heat (reformation required heat amount) Qr to be supplied from the outside in order to maintain the reforming temperature at Tr0 under the same conditions. As can be seen from FIG. 4, as the amount of water is increased and the amount of air is decreased, the required heat quantity of reforming Q
r increases. If the amounts of water and air are controlled optimally, there is a combination in which the amount of heat generated by the partial oxidation reaction becomes equal to the amount of heat absorbed by the steam reforming reaction, and the required heat amount of reforming Qr becomes zero.

In the present invention, the supply of heat to the reformer from the outside is based on the recovery of heat from the exhaust gas of the engine. The precondition for recovering heat from the exhaust gas of the engine is that the exhaust gas temperature Tex is higher than the reforming temperature Tr0,
It is necessary that the recoverable amount of exhaust heat Qe is larger than the required reforming heat Qr. Therefore, Tex> Tr0 and Qe> Q
r, and if the heat exchange efficiency of the heat exchanger that transfers heat from the exhaust gas to the reformer is ηhe and the exhaust heat amount is Qex, the recoverable amount Qe of the exhaust heat amount is approximately Qe = Qex × ηhe. . Naturally, when Qe is 0 or less, heat cannot be recovered from exhaust gas.

Therefore, in the present invention, when the reformer can and cannot recover the exhaust heat, in detail, the exhaust heat recoverable amount Qe is estimated from the operating state of the engine, and the exhaust gas is recovered in accordance with Qe. Is switched.

More specifically, when Qe is 0 or less, the switching valve 19 switches the flow path of the exhaust gas to the bypass passage 18 to prevent heat from flowing from the reformer 8 to the exhaust gas, thereby recovering the exhaust gas. After setting the possible calorific value to 0, the reforming raw material flow controller 15 adjusts the amounts of fuel, water, and air to be supplied to the reformer 8 by the amount of heat generated by the partial oxidation reaction and the amount of heat absorbed by the steam reforming reaction. By controlling them to be equal, the reforming temperature is maintained at Tr0.

When Qe exceeds 0, the flow path of the exhaust gas is switched to the reformer 8 by the switching valve 19, and the reforming material 8 is used to recover the exhaust heat.
By controlling the amounts of fuel, water, and air fed into the reformer 8, the required reforming heat amount Qr to be supplied to the reformer 8 is supplemented by the exhaust heat calorie recoverable amount Qe, so that the reforming temperature is Tr0.
To maintain. This makes it possible to provide a highly efficient system regardless of the engine operating state. That is, when Qe exceeds 0, part or all of the calorific value during the partial oxidation reaction is supplemented with Qe to increase the rate of the steam reforming reaction that is advantageous in terms of thermal efficiency, and increase the partial oxidation reaction. The reformed form is shifted in the direction of decreasing the ratio.

Therefore, as shown in FIG. 5, the control unit 21 functions as a means for estimating the recoverable amount of exhaust heat, a function as a switching control means for switching the flow path of the exhaust gas by controlling the switching valve 19, The function as reforming material control means for controlling the supply amounts of fuel, water, and air to the reformer 8 under the control of the flow rate controller 15 is provided as software.

A specific example of the control executed by the control unit 21 will be described with reference to the flowchart of FIG. In step 1 (referred to as S1 in the figure, the same applies hereinafter),
Based on signals from various sensors, recoverable amount of exhaust heat Qe
Is estimated. A specific estimation method will be described later.

In step 2, the exhaust heat calorie recoverable amount Qe
Is compared with 0 to determine whether Qe ≦ 0 or Qe> 0. Q
If e ≦ 0, the process proceeds to step 3 where the bypass passage 18
By switching the switching valve 19 so that exhaust gas flows to the side, the amount of heat that can be recovered is set to zero. And step 4
To the reforming raw material flow controller 15 to feed the fuel, water, and air to the reformer 8 (the ratio of air to fuel A / F).
And the ratio of water to fuel (S / F) is controlled so that the calorific value and the heat absorption amount are balanced so that the required reforming heat amount Qr = 0. More specifically, A / F and S / F are controlled so as to have such a relationship.

If Qe> 0, the routine proceeds to step 5, where the switching valve 19 is switched so that exhaust gas flows to the reformer 8 side.
Then, the process proceeds to step 6, where the reforming raw material flow controller 15 inputs the amounts of fuel, water, and air to the reformer 8 (the ratio of air to fuel A / F and the ratio of water to fuel S / F).
Is controlled so that the required reforming heat quantity Qr = Qe, in other words, the proportion of the steam reforming reaction increases according to the exhaust heat calorie recoverable quantity Qe.

More specifically, using the ratio A / F of air to fuel and the ratio S / F of water to fuel as parameters, the required reforming heat quantity qr per unit fuel is determined as shown in FIG. Therefore, when the exhaust heat calorie recoverable amount Qe is 0 or more, Qr = qr × Gf1 (where Gf
A / F and S are set so that the required reforming heat amount Qr obtained by (1 is the fuel input amount) and the exhaust heat calorie recoverable amount Qe are equal.
/ F, and the amounts of fuel, water, and air to be charged into the reformer 8 are determined.

Practically, in the relationship of Qr = Qe, the required reforming heat quantity qr per unit fuel is calculated from the fuel input amount Gf1.
= Qr / Gf = Qe / Gf1 and, based on a predetermined table, an optimal combination of the air ratio A / F and the water ratio S / F in correspondence with the required reforming heat quantity qr per unit fuel. , A / F and S / F may be determined.

When Qe is 0 or less, qr =
A / F and S / F may be determined at 0, but q
Of a plurality of combinations where r = 0, a predetermined optimal combination is set.

Next, a method for estimating the recoverable amount of exhaust heat Qe will be described with reference to the flowchart of FIG. In step 11, the engine speed Ne and the engine speed N
Volumetric efficiency (filling efficiency) obtained by referring to the table from e
The working gas amount Gs is calculated from ηv and the engine exhaust amount Vin (constant value). However, the correction is made based on the intake air temperature, the intake pressure, and the reformed gas temperature (the temperature at the time of injection into the intake air). still,
An air flow meter may be arranged in the intake passage of the engine, and the working gas amount Gs may be calculated based on the signal.

In step 12, the amount of reformed gas Gf supplied to the engine from the engine load is calculated. Step 1
In 3, the exhaust gas composition is calculated from the working gas amount Gs and the reformed gas amount Gf, and the exhaust gas volume Vex and the exhaust specific heat Cex are calculated.
And ask.

In step 14, the exhaust heat quantity Qex = f (Vex, Cex, Tex) is determined from the exhaust gas volume Vex, the exhaust specific heat Cex, and the exhaust temperature Tex. In step 15, the exhaust heat quantity Qex, a constant (heat passage rate) H for determining the heat exchange performance between the exhaust gas and the reformer, the heat exchange area A,
Temperature difference ΔT between exhaust temperature Tex and reforming temperature Tr = Tex−T
r, the amount of exhaust heat recoverable Qe = Qex × H × A × Δ
Calculate T × C1. Here, C1 is a learning correction coefficient.

Next, the learning correction by the learning correction coefficient C1 will be described. When the amount of fuel, water, and air to be supplied to the reformer 8 is determined and controlled so that the exhaust heat calorie recoverable amount Qe is equal to or more than 0 and Qe is equal to the reforming required heat amount Qr, the reforming temperature Tr is kept almost constant.

However, when the performance of the reformer 8 decreases, an error occurs in the estimated Qe, or the performance of the reforming catalyst changes, and the reaction mode shifts to the endothermic reaction side or the exothermic reaction side. When an error occurs in the estimated Qr, a change occurs in the reforming temperature Tr.

Specifically, if Qe <Qr, the reforming temperature Tr increases, and if Qe> Qr, the reforming temperature Tr decreases. Therefore, when the reforming temperature Tr rises, Q
The learning correction coefficient C1 is rewritten toward the increasing side so as to increase the estimated value of e. Thereby, the rate of the steam reforming reaction is increased so that Qr is increased in accordance with Qe, and the reforming temperature Tr can be lowered.

Conversely, when the reforming temperature Tr drops, Q
The learning correction coefficient C1 is rewritten in the direction of decreasing the estimated value of e. Thereby, the rate of the partial oxidation reaction is increased so that Qr is reduced corresponding to Qe, and the reforming temperature Tr can be increased.

FIG. 9 is a flowchart of the learning correction.
In step 21, it is determined whether a predetermined learning condition is satisfied. The predetermined learning condition is that, at least, the exhaust heat calorie recoverable amount Qe is 0 or more, and Qe and the required reforming heat amount Q
fuel to be supplied to the reformer 8 so that r is equal to
This is the case where the amounts of water and air are determined and controlled.

If the learning condition is satisfied, the routine proceeds to step 22, where the rate of change ΔTr of the reforming temperature Tr is measured.
After the measurement, in step 23, it is determined whether or not the temperature change rate ΔTr has exceeded a predetermined value on the + side (temperature rise). If it has exceeded, the learning correction coefficient C1 is rewritten to an increasing side in step 24.

In step 25, the temperature change rate ΔTr
It is determined whether or not exceeds a predetermined value on the negative side (temperature drop). If it does, the learning correction coefficient C1 is rewritten to a decreasing side in step 26.

[Brief description of the drawings]

FIG. 1 is a system diagram of an internal combustion engine with a fuel reformer showing one embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a reforming temperature and a reformed gas composition.

FIG. 3 is a diagram showing the relationship between the input amounts of water and air and the calorific value ratio.

FIG. 4 is a diagram showing a relationship between input amounts of water and air and a required calorific value of reforming.

FIG. 5 is a block diagram of basic control.

FIG. 6 is a flowchart of basic control.

FIG. 7 is a characteristic diagram for A / F and S / F control.

FIG. 8 is a flowchart of estimating the recoverable amount of exhaust heat.

FIG. 9 is a flowchart of learning correction.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 intake passage 6 gas fuel injection valve 7 exhaust passage 8 reformer 9 fuel tank 10 fuel pump 11 water tank 12 water pump 14 air pump 15 reforming material flow controller 16 vaporization mixer 17 reformed gas supply passage 18 Bypass passage 19 switching valve 21 control unit 26 exhaust temperature sensor 27 reforming temperature sensor

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Muneyoshi 2 Takara-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (9)

[Claims] 1. An internal combustion engine with a fuel reforming device having a reformer for reforming a hydrocarbon-based fuel with a reforming catalyst and supplying a reformed gas to the engine. A bypass passage connecting the upstream side and the downstream side of the reformer of the exhaust passage to bypass the reformer; and a flow path of the exhaust gas passing through the reformer side and the bypass passage side. A switching valve that can be switched to the above, so that when the reformer can recover the exhaust heat, the exhaust is guided to the reformer side, and when the reformer cannot recover the exhaust heat, the exhaust is guided to the bypass passage side. An internal combustion engine with a fuel reformer, comprising: switching control means for controlling a switching valve. 2. An internal combustion engine with a fuel reformer, comprising a reformer for reforming a hydrocarbon-based fuel with a reforming catalyst, and supplying a reformed gas to the engine. A bypass passage connecting the upstream side and the downstream side of the reformer of the exhaust passage to bypass the reformer; and a flow path of the exhaust gas passing through the reformer side and the bypass passage side. A switching valve that can be switched to an exhaust gas amount, an exhaust heat amount recoverable amount estimating means for estimating a recoverable amount of exhaust heat amount to the reformer, and a switching control means for controlling the switching valve according to the exhaust heat amount recoverable amount. An internal combustion engine with a fuel reformer, comprising: 3. The fuel reformer according to claim 2, wherein the switching control means controls the exhaust gas to be guided to the bypass passage when the recoverable amount of the exhaust heat is 0 or less. Internal combustion engine. 4. The fuel reformer according to claim 3, wherein the switching control means controls the exhaust gas to be guided to the reformer when the recoverable amount of the exhaust heat exceeds zero. With internal combustion engine. 5. When the recoverable amount of exhaust heat is 0 or less,
Supply of fuel, water and air to the reformer in such a direction that the calorific value by the partial oxidation reaction between fuel and air in the reformer and the heat absorption by the steam reforming reaction between fuel and steam become equal. The internal combustion engine with a fuel reformer according to claim 3 or 4, further comprising a reforming material control means for controlling the amount. 6. The fuel and steam for the partial oxidation reaction of fuel and air in the reformer when the recoverable amount of exhaust heat exceeds 0 compared to when the recoverable amount of exhaust heat is 0 or less. 6. A reforming raw material control means for controlling a supply amount of fuel, water and air to a reformer so as to increase a rate of a steam reforming reaction with the reforming material. An internal combustion engine with a fuel reformer according to any one of the preceding claims. 7. The reforming raw material control means decreases an air supply amount to a fuel and increases a water supply amount in order to increase a ratio of a steam reforming reaction to a partial oxidation reaction. An internal combustion engine with a fuel reformer according to claim 6. 8. An exhaust heat calorie recoverable amount estimating means for estimating a recoverable amount of exhaust heat calorie to a reformer based on at least a parameter relating to a working gas amount of an engine and an exhaust gas temperature. The internal combustion engine with a fuel reformer according to any one of claims 2 to 7, characterized in that: 9. The exhaust heat calorie recoverable amount estimating means learns and corrects the exhaust calorie recoverable amount based on a rate of change of the temperature in the reformer. An internal combustion engine with a fuel reformer according to any one of the preceding claims.