JP2002047957A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of suppressing SOx poisoning phenomenon of exhaust gas purifying catalyst of NOx storage reduction type and improving a purification rate of exhaust gas further. SOLUTION: This internal combustion engine 1 burning air-fuel mixture in which air and fuel are mixed in a cylinder 3 to obtain an output is provided with the exhaust gas purifying catalyst 39 of NOx storage reduction type for purifying exhaust gas exhausted from the cylinder 3 after the combustion of the air-fuel mixture and sulfur component solidifying means 16, 41, 42 for solidifying sulfur component which becomes the cause for generating sulfur oxide after the combustion in the internal combustion engine. The sulfur component solidifying means 16, 41, 42 solidify 70% or more of sulfur component that exhaust gas contains before exhaust gas flows into the exhaust gas purifying catalyst 39.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas for an internal combustion engine capable of suppressing a decrease in an exhaust gas purification rate due to SOx poisoning of a NOx storage reduction type exhaust gas purification catalyst and further increasing the exhaust gas purification rate. It relates to a purification method.

[0002]

2. Description of the Related Art The exhaust gas of an internal combustion engine is released to the atmosphere after being purified by an exhaust purification catalyst such as a three-way catalyst. Then, as one of such an exhaust gas purifying catalyst, oxygen O ₂ is occluded nitrogen oxides NOx when in excess, nitrogen oxides occluded when less oxygen O ₂ in the exhaust gas in the exhaust gas NOx is released and reduced (at this time, carbon monoxide CO and hydrocarbons HC in the exhaust gas are oxidized), and an NOx storage reduction type exhaust purification catalyst has been used.

[0003] By using such an exhaust purification catalyst, nitrogen oxides NOx in exhaust gas during lean operation are stored, and nitrogen oxides stored during stoichiometric or rich operation are stored.
By releasing and reducing NOx, the exhaust gas purification rate can be further improved. Such NOx storage-reduction type exhaust purification catalysts are useful for improving the exhaust purification rate of lean burn engines that perform lean operation more aggressively than ordinary engines, and also contribute to improving fuel economy. I have.

[0004]

However, these NOx
The storage reduction type exhaust purification catalyst has the property of storing sulfur oxides SOx more stably than nitrogen oxides NOx. Sulfur oxide SOx in exhaust gas is generated by oxidizing a sulfur component contained in fuel or engine oil by combustion of an internal combustion engine. Although the sulfur component contained in fuel and engine oil is very small,
Since the NOx storage-reduction type exhaust purification catalyst is stably stored, the amount of storage is gradually accumulated and increased. If a large amount of sulfur oxide SOx is stored in the NOx storage reduction type exhaust purification catalyst, it becomes impossible to properly store, release, and reduce nitrogen oxide NOx. This is the so-called NO
This is the "SOx poisoning" phenomenon in x-reduction-type exhaust purification catalysts.

[0005] In a conventional NOx storage reduction type exhaust purification catalyst, most of the storage capacity is nitrogen oxide NOx when it is new.
Although it is used for occlusion of x, when it is subjected to SOx poisoning, only a small amount of occlusion capacity is used for occlusion of nitrogen oxides NOx. If this SOx poisoning phenomenon can be suppressed, the storable and desorbable amounts of nitrogen oxide NOx can be increased, and the exhaust purification performance of the NOx storage-reduction type exhaust purification catalyst can be significantly improved. it can. In addition, such
Japanese Patent Application Laid-Open
Although those described in 2000-27712 publication are also known,
The effect is not yet sufficient, and the inventors have achieved the present invention with the aim of further improving exhaust gas purification performance.

Accordingly, an object of the present invention is to provide a method of purifying exhaust gas of an internal combustion engine which can suppress the SOx poisoning phenomenon of a NOx storage reduction type exhaust gas purification catalyst and further improve the purification rate of exhaust gas. It is in.

[0007]

According to a first aspect of the present invention, there is provided an internal combustion engine which obtains an output by burning an air-fuel mixture in a cylinder to obtain an output. It is provided with a NOx storage reduction type exhaust purification catalyst that purifies exhaust gas discharged from a cylinder, and a sulfur component solidification unit that solidifies a sulfur component that causes sulfur oxide to be generated after combustion of the internal combustion engine. The sulfur component solidifying means solidifies 70% or more of the sulfur component contained in the exhaust gas before the exhaust gas flows into the exhaust purification catalyst.

According to a second aspect of the present invention, in the first aspect of the invention, the sulfur component solidifying means solidifies at least 70% of the sulfur component in the exhaust gas discharged from the cylinder. It is characterized by having it.

[0009] The ratio of solidified sulfur oxides after combustion of the internal combustion engine, that is, the solidification rate of the sulfur component, is determined from experiments described below. Sulfur content by weight
A fuel containing 500 ppm containing a solidifying agent was used as a test fuel, and the engine speed was 2,000 rpm and the load was 60 N.
Measure the SOx concentration in the exhaust gas when operating the engine under the conditions of m, and solidify the sulfur component from the decrease in the SOx concentration in the exhaust gas when operating with normal fuel without adding a solidifying agent. Calculate as rate.

According to a third aspect of the present invention, in the internal combustion engine according to the first or second aspect, the sulfur component solidifying means solidifies the sulfur component in the exhaust gas by adding a sulfur component solidifying agent. It is characterized by having

According to a fourth aspect of the present invention, in the third aspect of the invention, the sulfur component solidifying means includes adding a sulfur component solidifying agent of 1.5 times or more mol of the sulfur component to be solidified. Features.

According to a fifth aspect of the present invention, in the third aspect of the present invention, the sulfur component solidifying means includes a sulfur component solidifying means for reducing the sulfur component in the exhaust gas to 70% to 95%. It is characterized by adding a component solidifying agent.

According to a sixth aspect of the present invention, in the internal combustion engine according to the third aspect, the sulfur component solidifying agent is an element having an oxidizing function of oxidizing a sulfur component with an alkali metal element or an alkaline earth metal element. And is characterized by containing.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the internal combustion engine of the present invention will be described below. FIG. 1 shows an internal combustion engine (engine) 1 of the present embodiment.

The engine 1 described below is a multi-cylinder engine. Here, only one cylinder is shown as a sectional view. The engine 1 is an in-cylinder injection engine that injects fuel directly into the cylinder 3, and is a lean burn (lean burn) engine. The engine 1 has a spark plug 2
Thus, a driving force is generated by igniting the air-fuel mixture in each cylinder 3. At the time of combustion of the engine 1, air taken in from the outside passes through the intake passage 4 and is mixed with fuel injected from the injector 5 to form an air-fuel mixture. The interior of the cylinder 3 and the intake passage 4 are opened and closed by an intake valve 6. The air-fuel mixture burned inside the cylinder 3 is exhausted to the exhaust passage 7 as exhaust gas.
An exhaust valve 8 is provided between the inside of the cylinder 3 and the exhaust passage 7.
Is opened and closed by

A throttle valve 9 for adjusting the amount of intake air to be taken into the cylinder 3 is provided on the intake passage 4. The throttle valve 9 is connected to a throttle position sensor 10 for detecting the opening degree. Accelerator pedal 1 attached to throttle valve 9
An accelerator position sensor 12 for detecting the depression position of the throttle valve 1 and a throttle motor 13 for driving the throttle valve 9 are also provided. Although not shown in FIG. 1, an intake air temperature sensor for detecting the temperature of intake air is also provided on the intake passage 4.

On the downstream side of the throttle valve 9,
A surge tank 14 is formed.
, A vacuum sensor 15 and a cold start injector 17 are provided. The vacuum sensor 15 detects the pressure in the intake passage 4 (intake pipe pressure). The cold start injector 17 is connected to the engine 1
The fuel is diffused and sprayed into the surge tank 14 at the time of a cold start to form a homogeneous air-fuel mixture.

A swirl control valve 18 is provided further downstream of the surge tank 14. The swirl control valve 18 is used for lean combustion (stratified combustion).
This is for generating a stable swirl inside the cylinder 3 at times. Along with the swirl control valve 18, an SCV position sensor 19 for detecting the opening of the swirl control valve 18, a DC motor 20 for driving the swirl control valve 18, and the like are also provided.

The opening and closing timing of the intake valve 6 in the engine 1 of the present embodiment can be variably controlled by a variable valve timing mechanism 21. The open / close state of the intake valve 6 can be detected by a cam position sensor 22 that detects the rotational position of a camshaft on which a cam for opening and closing the intake valve 6 is formed. further,
Near the crankshaft of the engine 1 is a crank position sensor 2 for detecting the rotational position of the crankshaft.
3 is attached. Crank position sensor 2
From the output of 3, the position of the piston 24 in the cylinder 3 and the engine speed can also be obtained. Engine 1
A knock sensor 25 for detecting the knocking of the engine 1 and a water temperature sensor 26 for detecting the temperature of the cooling water are also attached.

On the other hand, on the exhaust passage 7, on the side close to the body of the engine 1, a start-up catalyst 27 which is a normal three-way catalyst is disposed. Since the start-up catalyst 27 is close to the combustion chamber (cylinder 3) of the engine 1, the temperature is easily raised by the exhaust gas. It is arranged to be. The engine 1 is a four-cylinder engine, and is provided with two start-up catalysts 27, one for each two cylinders. An exhaust gas temperature sensor 28 is attached to each starting catalyst 27, and the exhaust gas temperature sensor 28 detects the temperature of the exhaust gas.

On the downstream side of the start-up catalyst 27, an exhaust pipe is integrated and an NOx storage reduction type exhaust purification catalyst 39 is provided. This NOx storage reduction type exhaust purification catalyst 39
Will be described in detail later. Exhaust purification catalyst 39
An air-fuel ratio sensor 40 for detecting the exhaust air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst 39 is mounted on the upstream side of the exhaust gas purification catalyst 39. As the air-fuel ratio sensor 40, a linear air-fuel ratio sensor capable of linearly detecting the exhaust air-fuel ratio from a rich region to a lean region, and an on-off detection of whether the exhaust air-fuel ratio is in a rich region or a lean region. An O ₂ sensor (oxygen sensor) or the like is used.

Further, an external EGR (Exhaust Gas Recirculation) for recirculating exhaust gas from the exhaust passage 7 to the intake passage 4 is provided.
ulation) passage 43 is formed. External EGR passage 43
The intake passage 4 is connected to the surge tank 14, and the exhaust passage 7 is connected to the upstream side of the starting catalyst 27. An EGR valve 44 for adjusting the amount of exhaust gas to be recirculated is provided on the external EGR passage 43. The EGR mechanism uses the negative pressure of the intake pipe in the intake passage 4 to return a part of the exhaust gas to the intake passage 4, thereby obtaining an effect of suppressing NOx generation and improving fuel efficiency. It should be noted that internal EGR control for obtaining the same effect by controlling the opening / closing timing of the intake valve 6 may be used together.

The fuel stored in the fuel tank 29 is delivered to the injector 5 of the engine 1 by a low-pressure fuel pump 30 for delivery, passes through a fuel filter 31, and is supplied after being pressurized by a high-pressure fuel pump 32. Is done. The engine 1 is capable of lean burn, and in order to perform good lean burn (stratified combustion), fuel is not directly injected into the cylinder 3 during the compression stroke to form a state suitable for stratified combustion. Therefore, the fuel is injected by the injector 5 after the pressure is increased.

A fuel pressure sensor 33 for detecting the pressure of the fuel for precise control is provided in association with the injector 5. The high-pressure fuel pump 32 is connected to the engine 1
, That is, the rotation of the camshaft on the exhaust valve 8 side to increase the pressure of the fuel. The fuel delivered by the low-pressure fuel pump 30 is supplied to the cold start injector 17 as it is.

Along with the fuel tank 29, the fuel tank 2
Charcoal canister 3 for collecting fuel evaporated in 9
4 are provided. The charcoal canister 34 has an activated carbon filter inside, and the activated carbon filter collects evaporated fuel. The collected fuel is purged into the intake passage 4 and burned in the cylinder 3 while the purge amount is controlled by the purge control valve 35. The fuel tank 29 has a return pipe 36 for returning the remaining fuel not injected into the fuel tank.
Is also attached.

The above-described spark plug 2, injector 5,
Throttle position sensor 10, accelerator position sensor 12, throttle motor 13, vacuum sensor 15, cold start injector 17, DC motor 2
0, the actuator of the variable valve timing mechanism 21;
The cam position sensor 22, crank position sensor 23, knock sensor 25, water temperature sensor 26, exhaust temperature sensor 28, purge control valve 35, air-fuel ratio sensor 40, EGR valve 44, intake temperature sensor, and other actuators and sensors It is connected to an electronic control unit (ECU) 37 that comprehensively controls the engine 1.

Note that, in the system shown in FIG.
An electronic control drive unit (EDU) 38 is provided between the U37 and the injector 5. EDU38 is E
The drive current from the CU 37 is amplified to drive the injector 5 with a high voltage and a large current. These actuators and sensors are controlled based on a signal from the ECU 37, or the detection result is obtained by an EC.
It is sent to U37. The ECU 37 includes a CPU for performing calculations therein, a RAM for storing various amounts of information such as calculation results, a backup RAM for storing the stored contents by a battery, and a ROM for storing each control program.
Etc. The ECU 37 controls the engine 1 based on various information amounts such as the intake passage pressure and the air-fuel ratio.

The NOx storage reduction type exhaust purification catalyst 39 will be described.

The exhaust gas purifying catalyst 39 is provided on a carrier having a surface coated with a thin film of alumina, a noble metal such as platinum, palladium or rhodium, or an alkali coating (K, Na, Li, Cs) on an alumina coating layer. ), Alkaline earth metals (Ba, Ca, etc.) or rare earth elements (L
a, Y, etc.) and the NOx contained in the exhaust gas when the engine is operated at a lean air-fuel ratio.
Can be occluded. For this reason, the exhaust purification catalyst 39 has a function as a normal three-way catalyst, that is, a function to purify HC, CO, and NOx in exhaust gas when burned in the vicinity of the stoichiometric air-fuel ratio. Can store NOx contained in the exhaust gas.

The NOx stored in the exhaust purification catalyst 39 is released when burned at a rich air-fuel ratio or a stoichiometric air-fuel ratio (stoichiometric air-fuel ratio), and is reduced and purified by HC and CO in the exhaust gas ( At this time, HC and CO are simultaneously oxidized and purified. Therefore, the NOx of the exhaust purification catalyst 39
When it is determined that the occluded amount is almost full, a so-called rich spike operation, in which the stored NOx is reduced by operating the engine for a short time at the rich air-fuel ratio, may be forcibly performed.

As described above, the exhaust gas purifying catalyst 39 has NO
It has the property of storing SOx more stably than x, which causes SOx poisoning. In the present embodiment, such a sulfur component causing SOx is solidified, the SOx concentration in the exhaust gas is reduced, and the amount of SOx stored in the NOx storage reduction type exhaust purification catalyst 39 is reduced. As a result, the capacity (NOx storable amount) of the exhaust purification catalyst 39 used for NOx occluding and reducing is increased, and N2 in the exhaust gas is reduced.
The purification rate of Ox can be improved.

For example, the above-described rich spike operation may not be performed depending on the operation state. Therefore, it is better that the NOx storable amount of the exhaust purification catalyst 39 is large, and if the storable amount is large, NOx cannot be completely absorbed. Thus, it is possible to prevent NOx from flowing downstream. The internal combustion engine of the present embodiment uses a sulfur component solidifying agent to solidify the sulfur component.

The sulfur component in the exhaust gas is solidified by using a sulfur component solidifying agent (hereinafter, also simply referred to as “solidifying agent”). It should just be. In this case, the sulfur component solidifying agent may be added to the intake air upstream of the cylinder 3, may be added in the cylinder 3, or may be added to the exhaust gas discharged from the cylinder 3. You may add to it.
Further, it may be added to fuel (gasoline) in advance, or may be added to a fuel tank.

The solidifying agent of the present embodiment contains a metal element having a function of oxidizing a sulfur component (hereinafter, also simply referred to as “metal element having an oxidation function”) and a basic metal element. By having both components, the sulfur component can be effectively solidified. Here, it is effective that the metal element having an oxidation function is a transition element. Further, the basic metal element is preferably an alkali metal element or an alkaline earth metal element, and particularly preferably an alkali metal having an atomic number higher than that of potassium.

Specific examples of the metal element having an oxidation function include Pt, Pd, Rh, Fe, Ce, In, Ag,
There are Au and Ir. Among them, those other than In are transition elements. On the other hand, as the basic metal element, specifically, Li, Na, K, Rb, Cs, Fr, Be, Mg,
There are Ca, Sr, Ba, Ra, Al, Zn, Zr, and La. Of these, alkali metals are Li, Na, K, R
b, Cs, and Fr. Among them, those having an atomic number equal to or greater than that of potassium are K, Rb, Cs, and Fr. Alkaline earth metals are Be, Mg, Ca, Sr,
Ba and Ra.

It is considered that the solidification of the sulfur component is performed as follows (where the metal element having an oxidizing function is M
_1, and the basic metal element and M _2). SO ₂ and SO ₃ are generated by the combustion of the engine 1. These react as follows: SO ₂ − (M ₁ ) → SO ₃ → M ₂ SO ₃ → M ₂ SO ₄ .

As described above, by adding a metal element having an oxidizing function to the solidifying agent, the oxidation reaction of the sulfur component is facilitated. That is, as described above, SO ₂ is likely to become SO ₃ , and the solidification rate of sulfur can be improved. Then, the oxidized sulfur oxide is solidified as a sulfite or a sulfate by the basic metal element.

At this time, by using an alkali metal having an atomic number equal to or greater than that of potassium as the basic metal element, the solidification rate of the sulfur component can be improved. This is because an alkali metal having an atomic number higher than that of potassium has a strong basicity and is easily associated with a sulfur component. In addition to the above, SO ₂ → M ₂ SO ₂ − (M ₁ ) → M ₂ SO ₃ → It is considered that a reaction such as M ₂ SO ₄ occurs, and as a result, the solidification rate of the sulfur component is improved. (In the above description, the metal element M ₁ having an oxidizing function is considered to oxidize a compound M ₂ SO ₂ of sulfur dioxide gas SO ₂ and a basic metal element M _2. )

Normally, during combustion of an internal combustion engine such as the engine 1
Under high temperature during combustion such as _TwoIs once SO_ThreeAcid
But chemically equilibrated with SO_ThreeSulfurous gas rather than gas
SO_TwoThe above-mentioned reaction does not occur because it is in the state
Therefore, an improvement in the solidification rate of sulfur cannot be expected. In addition, as SOx
Can be SO etc., but this is due to oxidation
Tte SO_TwoAnd SO_ThreeThen, as described above,
It is solidified.

In the present embodiment, the sulfur component is solidified by the above-described method, but 70% or more of the sulfur component that causes the formation of sulfur oxides after combustion is solidified. The solidification of the sulfur component may be performed at any time. If possible, 70% or more of the sulfur component in the exhaust gas may be solidified by solidifying the sulfur component in the fuel and engine oil before the fuel is burned in the cylinder 3. Further, the sulfur component may be solidified almost simultaneously with the combustion of the fuel in the cylinder 3, or the exhaust gas discharged from the cylinder 3 may be subjected to a solidification process of the sulfur component.

When the solidification rate of the sulfur component contained in the exhaust gas is less than 70%, the remaining 30% or more of the gaseous SOx in the exhaust gas causes the SOx of the NOx storage reduction type exhaust purification catalyst to be reduced.
x Poisoning will not be much different from before. This is because, as described above, even if the ratio of SOx in the exhaust gas is low, SOx can be stably occluded in the exhaust purification catalyst 39, and if this accumulates, there is no room for occlusion of NOx as in the conventional case. It is because.

If the solidification of the sulfur component is performed at least before the exhaust gas flows into the exhaust purification catalyst 39, SOx poisoning of the exhaust purification catalyst 39 can be prevented. Also,
If the solidification of the sulfur component is terminated before the exhaust gas is discharged from the cylinder 3, the combustion of the engine 1 can be effectively used for solidification of the sulfur component.

The solidification rate of the above-mentioned sulfur component is 70%.
Even if it is at least 95%, it is preferable to be at most 95%. Since the solidification of the sulfur component naturally produces a solid, if the solidification is performed on the intake passage 4 or in the cylinder 3, the solid may cause knocking or poor combustion, or the vicinity of the combustion chamber. There is a concern that it will adhere as a deposit to In addition, the starting catalyst 27 and the exhaust purification catalyst 39 do not necessarily cause clogging. Solidification rate of 10
It can be predicted that the SOx poisoning improvement effect width of the exhaust purification catalyst 39 gradually decreases as the value approaches 0%. As a result, in consideration of the SOx poisoning improvement effect corresponding to the solidification rate and the above-mentioned possible effects, it is preferable to set the solidification rate to 95% or less.

Further, in order to obtain a solidification rate of 70% or more, the number of moles of the solidifying agent is 1.5 times or more the number of moles of the sulfur component to be solidified, that is, the solidifying agent is 1.5 times the sulfur component. It is preferable to add at least twice the molar amount. In addition, in the case of the above-mentioned solidifying agent, the number of moles of the solidifying agent is the number of moles of a basic metal that can directly react with the sulfur component. In addition, the number of moles is calculated by assuming that the amount of reacting when forming a salt without excess or shortage is 1 mole.

For example, when it is assumed that one mole of a sulfur component causes a sulfur oxide to be generated after combustion of the engine 1, this is solidified by the above-described method (K is used as a basic metal). The solidified substance is K ₂
SO ₄ That is, 2 moles of K are required for 1 mole of the sulfur component. That is, in this case, 1.5 times mol of the solidifying agent (basic metal) means that 1.5 × 2 = 3 mols of K in the solidifying agent.

In the process of solidifying a sulfur component (SOx such as SO ₂ or SO ₃ ), the solidifying agent can once react with NOx (however, since nitrate has a lower decomposition temperature than sulfate, The nitrate will eventually degrade).
For this reason, simply adding the solidifying agent in an amount equivalent to the sulfur component (1 mole) may cause a shortage in solidifying all the sulfur components. Therefore, in order to improve the solidification rate of the sulfur component, it is preferable to add an equivalent or more of a solidifying agent. The reaction product of the solidifying agent with SOx and NOx is sulfate and nitrate. The nitrate ion is monovalent and the sulfate ion is divalent. Depending on the NOx generation rate during combustion, the amount of NOx generated is usually Is the SOx generation amount or more, so the mole number of the solidifying agent (basic metal element) is at least 1.5 times the mole of the sulfur component (1 mole is necessary for the reaction with the sulfur component, and half of this It is preferable to add more than necessary) for the reaction with the nitrogen component.

Here, a graph showing the change in the solidification rate of the sulfur component when the addition amount of the solidifying agent is changed is shown in Table 1 below.
Shown in

[Table 1]

The vertical axis of the graph shown in Table 1 is the solidification rate of the sulfur component. The horizontal axis of the graph shown in [Table 1] is the number of moles of the immobilizing agent, and when the value is 1.5, it indicates that the solidifying agent of 1.5 times the sulfur component was added. . As can be seen from Table 1, when the amount of the solidifying agent added is close to 1.5 moles, the solidification rate of the sulfur component can be increased to 70% or more.

The solidifying agent may contain a metal element having an oxidizing function or a basic metal element as an ion, or may contain a soluble compound.
The solidifying agent may be a solid or a liquid, or may be a gas, and the above-mentioned soluble compound dissolved in a solvent,
It can be provided in various forms such as a solid that dissolves gasoline as a solvent as a solvent.

For example, it is conceivable to dissolve potassium citrate or calcium naphthenate, which is a compound of a basic metal, in ethanol to form ions in a solution, and to add these ions to gasoline as a fuel. Alternatively, it is conceivable to dissolve potassium carbonate, sodium carbonate, or calcium hydroxide, which is a compound of a basic metal, with water to form ions in an aqueous solution, and to spray and add the ions onto an intake passage, a cylinder, or an exhaust passage.

As described above, by solidifying most of the sulfur components contained in the exhaust gas, NO
Since it becomes difficult for SOx to be stored in the x-storage-reduction type exhaust purification catalyst 39, the storage capacity of the exhaust purification catalyst 39 can be used for storing NOx, and the purification rate of NOx can be improved.

As described above, there are several methods for adding the solidifying agent. First, the case where the above-described sulfur component solidifying agent is mixed with fuel will be briefly described. The above-described internal combustion engine shown in FIG. 1 shows the configuration in this case. In this case, the entire engine 1 including the intake / exhaust system and the fuel system functions as a sulfur component solidifying means for solidifying the solidifying agent. Here, potassium is used as a basic alkali metal element, and a solution in which potassium citrate is dissolved in ethanol is used as a fixing agent. This fixing agent further contains Ce as a transition metal element having an oxidizing function as cerium octylate.

The solidifying agent was charged into the fuel tank 29. If the solidifying agent is added immediately after the gasoline tank is replenished with fuel, the mixing ratio with gasoline, which is the fuel, can be easily set to a predetermined mixing ratio, which is convenient. As described above, when the solidifying agent is added to gasoline as the fuel, the fuel is injected into the cylinder 3 and burned, whereby the above-described reaction of solidifying the sulfur component occurs, and the sulfur component in the exhaust gas ( Originally, the fuel or the sulfur component in the engine oil) is solidified and is no longer stored in the exhaust purification catalyst 39.

Next, the case where the above-mentioned sulfur component solidifying agent is added by spraying onto the intake passage 4 will be briefly described. FIG. 2 shows the configuration of the engine 1 and its periphery in this case. Note that the same or equivalent components as those shown in FIG. 1 described above are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, potassium is used as a basic alkali metal element, and an aqueous solution of potassium hydroxide is used as a fixing agent. This fixing agent further contains Ce as a transition metal element having an oxidizing function as cerium octylate.

A solidifying agent tank 41 for storing the solidifying agent is provided in association with the engine 1. A pipe is provided from the solidifying agent tank 41 to the surge tank 14, and a surge tank 1 is provided at a tip of the pipe.
A spray nozzle 16 for spraying the solidifying agent toward the inside of the nozzle 4 is connected. A spray pump 42 for spraying the solidifying agent is provided in the middle of the pipe. The spray pump 42 is driven by the electric power of the battery or a part of the output of the engine 1. Further, the spray nozzle 16
Is connected to the ECU 37 described above.
The spray timing and spray amount of the solidifying agent are controlled by this.

When the solidifying agent is sprayed on the intake air using the spray nozzle 16, the solidifying agent is directly sucked into the cylinder 3 and burned together with the fuel injected from the injector 5. As a result, the above-mentioned reaction for solidifying the sulfur component occurs, and the sulfur component in the exhaust gas (originally in the fuel or in the engine oil) is solidified and is not stored in the exhaust purification catalyst 39. . in this case,
The entire engine 1 including the intake / exhaust system and the fuel system, the spray nozzle 16 for supplying the solidifying agent, the solidifying agent tank 41, the spray pump 42, etc. function as a sulfur component solidifying means for solidifying the solidifying agent. I have.

Next, the case where the above-mentioned sulfur component solidifying agent is added by spraying into the cylinder 3 will be briefly described. FIG. 3 shows the configuration of the engine 1 and its periphery in this case. The same or similar components as those shown in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. Again, potassium is used as the basic alkali metal element, and an aqueous solution of potassium hydroxide is used as the fixing agent. This immobilizing agent includes C as a transition metal element having an oxidizing function.
e is further contained as cerium octylate.

Further, a solidifying agent tank 41 for storing the solidifying agent is provided in association with the engine 1. A pipe is provided from the solidifying agent tank 41 to the cylinder 3, and a spray nozzle 16 for spraying the solidifying agent toward the inside of the cylinder 3 is connected to a tip of the pipe. A spray pump 42 for spraying the solidifying agent is provided in the middle of the pipe. Spray pump 42
Is driven by the power of the battery or a part of the output of the engine 1. Further, the spray nozzle 16 is connected to the above-mentioned ECU 37, and the spray timing and the spray amount of the solidifying agent are controlled by the ECU 37.

When the solidifying agent is sprayed into the cylinder 3 using the spray nozzle 16, the above-described reaction for solidifying the sulfur component occurs, and the sulfur component in the exhaust gas (originally in the fuel or engine oil) The sulfur component therein is solidified and no longer stored in the exhaust purification catalyst 39. Also in this case, the entire engine 1 including the intake / exhaust system and the fuel system, the spray nozzle 16 for supplying the solidifying agent, the solidifying agent tank 41,
The spray pump 42 and the like function as a sulfur component solidifying means for solidifying the solidifying agent.

Next, the case where the above-mentioned sulfur component solidifying agent is added by spraying onto the exhaust passage 7 will be briefly described. FIG. 4 shows the configuration of the engine 1 and its surroundings in this case. The same or similar components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. Again, potassium is used as the basic alkali metal element, and an aqueous solution of potassium hydroxide is used as the fixing agent. This fixing agent includes Ce as a transition metal element having an oxidizing function.
As cerium octylate.

The solidifying agent tank 41 for storing the solidifying agent is provided in association with the engine 1. A pipe is provided from the solidifying agent tank 41 to the exhaust passage 7, and a spray nozzle 1 for spraying the solidifying agent onto the exhaust passage 7 on the upstream side of the exhaust purification catalyst 39 is provided at a tip of the pipe.
6 are connected. A spray pump 42 for spraying the solidifying agent is provided in the middle of the pipe. The spray pump 42 is driven by the electric power of the battery or a part of the output of the engine 1. Further, the spray nozzle 16 is connected to the ECU 37 described above,
The spray timing and spray amount of the solidifying agent are controlled by the ECU 37.

When the solidifying agent is sprayed onto the exhaust passage 7 using the spray nozzle 16, the solidifying agent mixes with the exhaust gas containing the sulfur component, and the above-described reaction for solidifying the sulfur component occurs. During this reaction, the heat of the exhaust gas can accelerate the reaction. By this reaction, the sulfur component in the exhaust gas (originally in the fuel or in the engine oil) is solidified and is not stored in the exhaust purification catalyst 39. Also in this case, the entirety of the engine 1 including the intake / exhaust system and the fuel system, the spray nozzle 16 for supplying the solidifying agent, the solidifying agent tank 41, the spray pump 42, and the like solidify the sulfur component solidifying means for solidifying the solidifying agent. Functioning as

Next, the above-mentioned sulfur component solidifying agent was added to the external EG.
The case of adding by spraying on the R passage 43 will be briefly described. FIG. 5 shows the configuration of the engine 1 and its periphery in this case. The same or equivalent components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. even here,
Potassium is used as a basic alkali metal element, and an aqueous solution of potassium hydroxide is used as a fixing agent.
This fixing agent further contains Ce as a transition metal element having an oxidizing function as cerium octylate.

A solidifying agent tank 41 for storing the solidifying agent is provided in association with the engine 1. A pipe is arranged from the solidifying agent tank 41 to above the external EGR passage 43, and a spray nozzle 16 for spraying the solidifying agent into the inside of the external EGR passage 43 is connected to a tip of the pipe. A spray pump 42 for spraying the solidifying agent is provided in the middle of the pipe. The spray pump 42 is driven by the electric power of the battery or a part of the output of the engine 1. Further, the spray nozzle 1
6 is connected to the ECU 37 described above,
7 controls the spray timing and spray amount of the solidifying agent.

Using the spray nozzle 16, the external EGR passage 4
When the solidifying agent is sprayed on the exhaust gas 3, the solidifying agent mixes with the exhaust gas containing the sulfur component, and further mixes with the intake air on the intake passage 4, which is directly sucked into the cylinder 3 and injected from the injector 5. The fuel is burned together with the fuel. As a result, the above-described reaction for solidifying the sulfur component occurs. By this reaction, the sulfur component in the exhaust gas (originally in the fuel or in the engine oil) is solidified and is not stored in the exhaust purification catalyst 39. Also in this case, the entirety of the engine 1 including the intake / exhaust system and the fuel system, the spray nozzle 16 for supplying the solidifying agent, the solidifying agent tank 41, the spray pump 42, and the like solidify the sulfur component solidifying means for solidifying the solidifying agent. Functioning as

[0066]

According to the first aspect of the present invention, the sulfur component that causes the generation of sulfur oxides after combustion of the internal combustion engine is transferred to the NOx storage reduction type exhaust purification catalyst installed on the exhaust passage. Because it solidifies before exhaust gas flows in,
SOx poisoning of the NOx storage reduction type exhaust purification catalyst can be suppressed, and purification of exhaust gas can be further improved. Importantly, 70% or more of the above-mentioned sulfur component is solidified. When the solidification rate is 70% or more, the SOx poisoning suppressing effect of the NOx storage reduction type exhaust purification catalyst can be sufficiently obtained, and the improvement of the purification performance can be surely realized.

According to the second aspect of the present invention, the sulfur component solidifying means ensures that 70% or more of the sulfur component in the exhaust gas discharged from the cylinder is solidified. In this case, it is possible to effectively promote the solidification of the sulfur component under high temperature and high pressure immediately after combustion in the cylinder or immediately after the combustion, which is convenient for improving the solidification rate.

According to the third aspect of the present invention, since the sulfur component solidifying means solidifies the sulfur component by adding the sulfur component solidifying agent, the apparatus can be simply configured. The internal combustion engine operates normally only by adding the sulfur component solidifying agent in the middle of the intake stroke to the exhaust stroke.
In order to solidify the sulfur component, a mechanism for adding the sulfur component solidifying agent is required, but there is no need to provide a special space or apparatus for the reaction.

According to the fourth aspect of the present invention, when the sulfur component solidifying agent is added at least 1.5 times the mole of the sulfur component to be solidified, the sulfur component solidifying agent is converted into NOx when the sulfur component is solidified. It is possible to compensate for the reacting amount and to dramatically improve the solidification rate of the sulfur component. If the solidification rate of the sulfur component improves, the NOx in the NOx storage reduction type exhaust purification catalyst
The storage capacity is also improved, and the exhaust gas purification performance can be improved.

According to the fifth aspect of the present invention, the means for solidifying the sulfur component has a solidification ratio of the sulfur component in the exhaust gas of 70% to 9%.
A sulfur component solidifying agent is added so as to be 5%. The effect of setting the solidification rate to 70% or more is as described above. There is a concern that the solid matter generated by solidification of the sulfur component may cause knocking or combustion failure, adhere as a deposit near the combustion chamber, or cause clogging of the exhaust purification catalyst. Considering the SOx poisoning improvement effect corresponding to the solidification rate and the effects that may be of concern described above, the solidification rate is 95%
By reducing the amount of solids produced as described below, it is possible to achieve a high-dimensional balance between the harmful effects of the solidified products and the improvement in exhaust gas purification performance.

According to the sixth aspect of the present invention, a basic metal element, which is an alkali metal element or an alkaline earth metal element, easily reacts with a sulfur component to form a salt (solid). The solidification rate of the component can be improved. As a result, the NOx storage capacity of the NOx storage reduction type exhaust purification catalyst can be improved, and the exhaust purification performance can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an internal combustion engine of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the internal combustion engine of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the internal combustion engine of the present invention.

FIG. 4 is a configuration diagram showing a fourth embodiment of the internal combustion engine of the present invention.

FIG. 5 is a configuration diagram showing a fifth embodiment of the internal combustion engine of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 3 ... Cylinder, 4 ... Intake passage, 7 ... Exhaust passage, 8 ... Exhaust valve, 16 ... Spray nozzle, 27 ... Start catalyst, 29 ... Fuel tank, 39 ... Exhaust purification catalyst (NOx Storage reduction type), 41 ... solidifying agent tank,
42: spray pump, 43: external EGR passage.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 25/00 F02M 25/00 H (72) Inventor Shinji Tsuji 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor (72) Inventor Tatsumi Mizuno 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masahiko Takeuchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yoshitsugu Ogura 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tetsuo Kawamura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F term (reference) 3G091 AA02 AA11 AA12 AA17 AA24 AA28 AB03 AB06 AB09 BA11 BA14 BA15 BA19 CA15 CB02 CB03 CB07 CB08 DA01 DA02 DA04 DB10 EA00 EA01 EA06 EA07 EA12 EA15 EA16 EA17 EA31 EA34 F B10 FB11 FB12 FC02 GA06 GB01X GB02W GB02Y GB03W GB03Y GB04W GB04Y GB05W GB05Y GB06W GB07W GB10X GB16X HA11 HA12 HA18 HA36 HA37 HB02 HB05 HB08 3G092 AA01 AA06 AA09 AA10 AA13 DEA03 A0319A04 DC04 HA05Z HA06X HB03X HC05Z HD01Z HD05Z HD07Z HE01Z HE03Z HE08Z HF08Z 3G301 HA01 HA04 HA06 HA13 HA14 HA15 HA17 HA19 JA21 LA03 LA05 LA07 LB03 LB04 LB06 LC03 MA01 MA11 PA07Z PA10Z PA11A PB08A PC08Z PD03Z PDZZ PDZZ PDZZ

Claims (6)

[Claims] 1. An internal combustion engine that obtains an output by burning a mixture of air and fuel in a cylinder, wherein the NOx storage reduction type purifies exhaust gas discharged from the cylinder after the combustion of the mixture. Exhaust purifying catalyst, and sulfur component solidifying means for solidifying a sulfur component that causes the formation of sulfur oxides after combustion of the internal combustion engine, wherein the sulfur component solidifying means, An internal combustion engine wherein 70% or more of a sulfur component contained in exhaust gas is solidified before flowing into an exhaust purification catalyst. 2. The apparatus according to claim 1, wherein the sulfur component solidifying means is configured to solidify at least 70% of a sulfur component in exhaust gas discharged from the cylinder. Internal combustion engine. 3. The internal combustion engine according to claim 1, wherein the sulfur component solidifying means solidifies the sulfur component in the exhaust gas by adding a sulfur component solidifying agent. 4. The internal combustion engine according to claim 3, wherein said sulfur component solidifying means adds 1.5 times or more moles of said sulfur component solidifying agent to the sulfur component to be solidified. 5. The sulfur component solidifying means adds the sulfur component solidifying agent such that the solidification rate of the sulfur component in the exhaust gas is 70% to 95%. An internal combustion engine according to claim 1. 6. The method according to claim 3, wherein the sulfur component solidifying agent contains an alkali metal element or an alkaline earth metal element and an element having an oxidation function of oxidizing the sulfur component. Internal combustion engine.