JP2006112401A - Catalyst temperature raising device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst temperature raising device capable of early heating a catalyst to an active temperature immediately after the engine is started. <P>SOLUTION: In this catalyst temperature raising device for early heating the catalyst 41 for purifying the exhaust emission 9 of an engine, the catalyst 41 is incorporated in an exhaust gas flow passage 2 in a carried state on a catalyst carrier 4, an ignition means 32 having an adding valve 31 with an injection hole 311 for injecting a fuel and a heating part 321 for igniting the fuel is installed in the exhaust gas flow passage 2 on the upstream side of the catalyst carrier 4. The adding valve 31 and the ignition means 32 are disposed at positions where the fuel injected from the injection hole 311 directly touches the heating part 321. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a catalyst temperature raising device for quickly raising the temperature of a catalyst for purifying exhaust gas of an engine.

  In recent years, an automobile equipped with a general gasoline engine has a catalyst installed in an exhaust pipe to purify harmful components contained in the exhaust gas. One of the harmful components, hydrocarbon (hereinafter referred to as HC), is discharged in large quantities as unburned gas, particularly in the warm-up state immediately after the engine is started. However, immediately after the engine is started, the catalyst has not reached an activation temperature at which a sufficient catalytic reaction can occur, and therefore HC cannot be sufficiently purified.

In order to solve the problems described above, for example, a method has been proposed in which an adsorbent such as zeolite is installed to suppress HC emission until the catalyst activation temperature is reached. However, an adsorbent such as zeolite adsorbs moisture and the like in exhaust gas in addition to HC, and therefore cannot sufficiently suppress HC emission.
A method of burning HC using air supplied to an exhaust pipe has been proposed. However, an air supply pump for supplying air to the exhaust pipe, a device for controlling it, and the like are required. Further, HC cannot be completely burned by the supplied air.

Further, Patent Document 1 proposes a method of rapidly heating and activating a catalyst using heat generated in association with an oxide hydration reaction. However, since it takes time to generate heat by the hydration reaction, the catalyst cannot be activated early.
Patent Document 2 proposes a method of injecting fuel into a combustor immediately after starting the engine, igniting it with a glow plug, and raising the temperature of exhaust gas. However, it takes time to inject fuel and ignite with a glow plug. Furthermore, it takes time to raise the temperature of the exhaust gas.

JP-A-7-180539 Japanese Patent No. 3015777

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a catalyst temperature raising device that can raise the temperature of the catalyst to the activation temperature quickly immediately after the engine is started.

The present invention is a catalyst temperature raising device for quickly raising the temperature of a catalyst for purifying exhaust gas of an engine,
The catalyst is built in the exhaust gas passage in a state of being supported on a catalyst carrier,
An upstream side of the catalyst carrier in the exhaust gas flow path has an addition valve having an injection port for injecting fuel, and an ignition means having a heat generating part for igniting the fuel. ,
The addition valve and the ignition means are provided in a catalyst temperature raising device, wherein the fuel injected from the injection port is disposed at a position in direct contact with the heat generating portion.

  The catalyst temperature raising apparatus of the present invention includes an addition valve provided with an injection port for injecting fuel and an exothermic part for igniting the fuel, upstream of the catalyst carrier in the exhaust gas passage. Ignition means. And the said addition valve and the said ignition means are arrange | positioned in the position where the fuel injected from the said injection port directly contacts the said heat generating part. Therefore, the temperature of the catalyst can be raised to the activation temperature at an early stage.

  That is, first, fuel is injected from the injection port toward the heat generating portion that has generated heat. Here, the addition valve and the ignition means are disposed at a position where the fuel injected from the injection port directly contacts the heat generating portion. Therefore, the injected fuel instantaneously contacts the heat generating part and ignites.

Since the flame generated by the ignition of the fuel is radiated into the exhaust gas passage from the upstream side of the catalyst carrier, the catalyst supported on the catalyst carrier is rapidly heated. Thereby, the said catalyst can be heated up to activation temperature at an early stage.
In other words, the catalyst temperature increasing device of the present invention is provided, and the above-described series of operations are performed at the time of starting the engine, so that immediately after the engine is started, the temperature of the catalyst can be raised to the activation temperature early and HC can be efficiently purified. it can.

  Thus, the catalyst temperature raising apparatus of the present invention can raise the temperature of the catalyst to the activation temperature quickly immediately after the engine is started.

  The injection port of the addition valve is housed in a heating chamber having an opening that opens to the exhaust gas flow path, and the addition valve is arranged to inject fuel toward the opening. (Claim 2). In this case, the injected fuel can be intensively injected into the opening without diffusing.

  Further, it is preferable that the heat generating portion of the ignition means is disposed so as to protrude into the exhaust gas passage from the temperature raising chamber through the opening. In this case, the fuel injected from the injection port toward the opening can be reliably ignited.

  Moreover, it is preferable that the said temperature rising chamber is exhibiting the structure where an opening cross-sectional area becomes small gradually as it approaches the said opening part (Claim 4). In this case, the injected fuel can be injected intensively into the opening without further diffusing.

Further, when the injection rate of the fuel injected by the addition valve is q (mm ³ / msec) and the opening area of the opening is A (mm ² ), 0.49 ≦ A / q ≦ 127.6. (Claim 5). When A / q is smaller than 0.49, there is a possibility that the fuel cannot be ignited because a large amount of fuel passes through the opening relative to the air. On the other hand, when A / q is larger than 127.6, there is a possibility that the fuel cannot be ignited because the fuel passing through the opening is less than the air.
Note that the opening area A is the cross-sectional area of the opening when the heat generating portion of the ignition means is arranged so as to protrude into the exhaust gas flow path from the heating chamber through the opening. To the area excluding the cross-sectional area of the heat generating portion in the opening.

Example 1
A catalyst temperature raising apparatus according to an embodiment of the present invention will be described with reference to FIGS.
The catalyst temperature increasing device 1 of this example is a catalyst temperature increasing device for quickly increasing the temperature of a catalyst 41 for purifying the exhaust gas 9 of the engine 8 as shown in FIGS.
The catalyst 41 is built in the exhaust gas passage 2 while being supported on the catalyst carrier 4, and an injection port 311 for injecting fuel is provided upstream of the catalyst carrier 4 in the exhaust gas passage 2. It has an addition valve 31 provided, and an ignition means 32 provided with a heat generating part 321 for igniting fuel.
The addition valve 31 and the ignition means 32 are disposed at a position where the fuel injected from the injection port 311 directly contacts the heat generating portion 321.
This will be described in detail below.

As shown in FIG. 1, the catalyst temperature raising apparatus 1 of this example is disposed in the middle of an exhaust path 81 connected to the engine 8. The exhaust gas 9 discharged from the engine 8 passes through the catalyst temperature raising device 1 and the muffler 811 and is discharged to the outside.
As shown in FIG. 2, an exhaust gas passage 2 through which the exhaust gas 9 is circulated is provided in the catalyst temperature raising apparatus 1, and both ends of the exhaust gas passage 2 are connected to an exhaust passage 81. A catalyst carrier 4 on which a catalyst 41 for purifying the exhaust gas 9 to be discharged is supported is built in the downstream side of the exhaust gas passage 2. In this example, a honeycomb structure made of ceramic was used as the catalyst carrier 4. Further, Pt (platinum) was used as the catalyst 41. Its activation temperature is 220 ° C. or higher.

  Further, as shown in the figure, on the upstream side of the exhaust gas passage 2, an addition valve 31 provided with an injection port 311 for injecting fuel, and an ignition means 32 provided with a heat generating part 321 for igniting the fuel, Is arranged. A heating chamber 3 having a circular opening 30 that opens to the exhaust gas flow path 2 is provided so as to cover the injection port 311 of the addition valve 31 and the heat generating part 321 of the ignition means 32. A structure in which the opening cross-sectional area gradually decreases toward 30 is exhibited.

  Further, as shown in the figure, the addition valve 31 is disposed so that the injection port 311 is accommodated in the temperature raising chamber and fuel can be injected toward the opening 30. Further, the heat generating portion 321 of the ignition means 32 is disposed so as to protrude from the temperature rising chamber 3 into the exhaust gas passage 2 through the opening 30. The addition valve 31 and the ignition means 32 are disposed at a position where the fuel injected from the injection port 311 directly contacts the heat generating portion 321. That is, the heat generating portion 321 is disposed in the fuel injection region S1.

Further, as shown in FIGS. 2 and 3, the heat generating portion 321 of the ignition means 32 has a side where the addition valve 31 is disposed from the center M of the opening 30 in order to make the fuel passing through the opening 30 evenly distributed. Projecting into the exhaust gas passage 2 from a position shifted to the opposite side. The opening area A of the opening 30 is an area obtained by subtracting the cross-sectional area of the heat generating part 321 in the opening 30 from the cross-sectional area of the opening 30 and is 660 mm ² in this example.

  As shown in FIG. 2, the addition valve 31 is connected to a fuel supply path 312 and is configured to be supplied with fuel injected from the injection port 311. Further, the ignition means 32 is connected to the power supply path 322, and is configured so that the ignition means 32 is energized at the same time when the engine 8 is started, and the heat generating portion 321 can be heated.

In this example, gasoline having an ignition point of −20 to −40 ° C. was used as the fuel. The injection rate q of the fuel injected by the addition valve 31 was set to 6 mm ³ / msec.
A glow plug was used as the ignition means 32. In addition, a ceramic heater or the like can be employed.

Next, the effect in the oxygen enrichment apparatus 1 of this example is demonstrated.
The catalyst temperature raising apparatus 1 of the present example includes an addition valve 31 provided with an injection port 311 for injecting fuel upstream of the catalyst carrier 4 in the exhaust gas flow path 2 and a heat generating portion 321 for igniting the fuel. And ignition means 32 having the above. The addition valve 31 and the ignition means 32 are disposed at a position where the fuel injected from the injection port 311 directly contacts the heat generating portion 321. Therefore, immediately after the engine 8 is started, the catalyst 41 can be raised to the activation temperature at an early stage.

  That is, first, simultaneously with the start of the engine 8, the ignition means 32 is energized from the power supply path 322, and the heat generating portion 321 is rapidly heated. Then, the fuel is injected from the injection port 311 toward the heat generating part 321. Here, the addition valve 31 and the ignition means 32 are disposed at a position where the fuel injected from the injection port 311 directly contacts the heat generating portion 321. Therefore, the injected fuel instantaneously contacts the heat generating portion 321 and ignites.

  Since the flame generated by the ignition of the fuel is radiated from the upstream side of the exhaust gas passage 2 to the downstream side where the catalyst carrier 4 is incorporated, the catalyst 41 carried on the catalyst carrier 4 is rapidly heated. As a result, immediately after the engine 8 is started, the catalyst 41 can be raised to the activation temperature at an early stage. And the catalyst 41 will be in the activated state which can fully raise | generate a catalytic reaction, and can purify HC efficiently.

  Thus, the catalyst temperature raising apparatus 1 of this example can raise the temperature of the catalyst to the activation temperature quickly immediately after the engine is started.

In this example, when the injection rate of the fuel injected by the addition valve 31 is q (mm ³ / msec) and the opening area of the opening 30 is A (mm ² ), the fuel ignition optimum region is 0.49 ≦ The condition of A / q ≦ 127.6 is satisfied. Therefore, the fuel injected from the addition valve 31 can be reliably ignited.

(Example 2)
In this example, the fuel injection state, the heat generating part temperature, the catalyst temperature, and the amount of HC in the case where the catalyst temperature increasing device 1 of Example 1 was provided were investigated and evaluated. The catalyst carrier 4, the catalyst 41, and the fuel were the same as those in Example 1.
For comparison, the following comparative product 1 and comparative product 2 were prepared and subjected to the same evaluation.
As shown in FIG. 4, the comparative product 1 does not have the temperature raising chamber 3, and the addition valve 31 and the ignition means 32 are located at positions where the fuel injected from the injection port 311 does not directly contact the heat generating portion 321, that is, The only difference from the catalyst temperature raising apparatus 1 of the first embodiment is that the heat generating portion 321 is disposed outside the fuel injection region S2.
The comparative product 2 is a conventional product that has a catalyst but does not have a catalyst temperature raising device.

Next, each investigation item will be described.
The fuel injection state is an investigation of the presence or absence of fuel injection.
The heat generating part temperature is a value obtained by measuring the temperature of the heat generating part 321 of the ignition means 32.
The catalyst temperature is obtained by measuring the temperature of the inlet end face of the catalyst carrier 4.
The HC amount is a value obtained by measuring the amount of unburned HC contained in the exhaust gas 9 that has passed through the catalyst carrier 4 carrying the catalyst 41.
In addition, the comparative product 2 which is not provided with the catalyst temperature raising device does not investigate the fuel injection state and the heat generating portion temperature.

The investigation result will be described with reference to FIGS. In the figure, the product of the present invention is indicated as E, the comparative product 1 as C1, and the comparative product 2 as C2. On the time axis, 0 (sec) indicates the engine start time.
First, the investigation result of the fuel injection state is shown in FIG. In the figure, the vertical axis represents the ON / OFF of the injection pulse, and the horizontal axis represents time (sec). The fuel injection is controlled by an injection pulse. ON indicates a state where fuel is being injected, and OFF indicates a state where fuel is not being injected.
As can be seen from the figure, the product of the present invention and the comparative product 1 start fuel injection after 3 seconds from the start of the engine. Further, the injection pulse after fuel injection is continuously ON. That is, it is understood that this is a continuous injection method in which fuel is continuously injected.

Next, the measurement result of the heat generating portion temperature is shown in FIG. In the figure, the vertical axis represents the heat generating part temperature (° C.), and the horizontal axis represents time (sec).
As can be seen from FIG. 5 (b), the product of the present invention and the comparative product 1 rapidly increased the temperature of the heat generating portion from the time of starting the engine and reached about 1000 ° C. after 3 seconds. At this time, the heat generating portion 32 is in a state where the fuel can be sufficiently ignited.
Further, as can be seen from the figure, the comparative product 1 maintains the heat generating portion temperature even after fuel injection, but the product of the present invention has a decrease in the heat generating portion temperature because the fuel is in direct contact with the heat generating portion 321. Is seen. However, there is no effect on fuel ignition.

Next, the measurement result of the catalyst temperature is shown in FIG. In the figure, the vertical axis represents the catalyst temperature (° C.) and the horizontal axis represents time (sec).
As can be seen from FIG. 5C, the comparative product 2 does not include the catalyst temperature raising device, and therefore the catalyst temperature rises slowly. Further, the comparative product 1 is in a position where the injected fuel is not in direct contact with the heat generating portion 321, and it takes time until the fuel is ignited. Therefore, there is a time difference between the fuel injection and the rise in the catalyst temperature. Compared with these, since the fuel of the present invention is in a position where the injected fuel is in direct contact with the heat generating portion 321, the catalyst temperature is rapidly increased from the time of fuel injection, and the activation temperature (220 ° C. or higher) of the catalyst 41 is rapidly increased. ). Therefore, the product of the present invention can raise the temperature of the catalyst 41 to the activation temperature at an early stage.

Next, the measurement result of the HC amount is shown in FIG. In the figure, the vertical axis represents HC amount (g) and the horizontal axis represents time (sec).
As can be seen from FIG. 5D, the comparative product 2 gradually reduces the HC amount from the time of engine start. Moreover, since the comparative product 1 has a time difference between the fuel injection and the catalyst temperature rise, there is also a time difference between the fuel injection and the reduction of the HC amount. Compared with these, the product of the present invention sharply reduces the amount of HC from the time of fuel injection. Therefore, the product of the present invention can efficiently purify HC immediately after starting the engine.

  Thus, it can be seen that the catalyst temperature raising apparatus 1 of the present invention can raise the temperature of the catalyst 41 to the activation temperature at an early stage immediately after starting the engine, and can efficiently purify HC.

(Example 3)
This example is an example in which the fuel injection is changed to the intermittent injection method in the catalyst temperature raising apparatus 1 of the first embodiment.
Others are the same as in the first embodiment.

Also in this example, as in Example 2, the fuel injection state and the heat generating part temperature were investigated and evaluated.
The investigation results will be described with reference to FIGS. 6 (a) and 6 (b). On the time axis in the figure, 0 (sec) indicates the engine start time.
First, the investigation result of the fuel injection state is shown in FIG. In the figure, the vertical axis represents the ON / OFF of the injection pulse, and the horizontal axis represents time (sec).
As can be seen from the figure, the catalyst temperature raising apparatus 1 of this example starts fuel injection 3 seconds after the engine is started. Further, the injection pulse after the fuel injection repeats ON / OFF every few seconds. That is, it is understood that this is an intermittent injection system in which fuel is intermittently injected.

Next, the measurement result of the heat generating portion temperature is shown in FIG. In the figure, the vertical axis represents the heat generating part temperature (° C.), and the horizontal axis represents time (sec).
As can be seen from FIG. 6 (b), the temperature of the heat generating portion is rapidly increased from the start of the engine, and reaches about 1000 ° C. after 3 seconds. At this time, the heat generating portion 32 is in a state where the fuel can be sufficiently ignited.

Further, as can be seen from the figure, in the state where the injection pulse is turned on after the fuel injection is started, the fuel directly contacts the heat generating portion 321 and thus the temperature of the heat generating portion decreases. There is no effect.
Further, in the case of this example, the fuel can be injected by intermittent injection while sufficiently taking in oxygen in the air, so that the fuel can be ignited more reliably.
The other functions and effects are the same as those of the first embodiment.

Example 4
As shown in FIG. 7, the present example is an example in which the ignition means 32 is an ignition means 33 made of a ceramic heater in the catalyst temperature raising apparatus 1 of the first embodiment.
As shown in the figure, the ignition means 33 includes a heat generating portion 331 as in the case of the ignition means 32 of the first embodiment, and the heat generating portion 331 is connected to the exhaust gas flow path from the temperature raising chamber 3 via the opening 30. It is arranged so as to protrude into 2.

Further, the ignition means 33 is connected to the power supply path 322, and is configured so that the ignition means 33 is energized from the power supply path 322 simultaneously with the start of the engine 8 and the heat generating portion 331 can generate heat.
Others are the same as those of the first embodiment and have the same effects as the first embodiment.

(Example 5)
As shown in FIG. 8, this example is an example in which auxiliary ignition means 39 is provided in the catalyst temperature raising apparatus 1 of the first embodiment.
As shown in the figure, the auxiliary ignition means 39 is provided with a heat generating part 391 for igniting the fuel, like the ignition means 32. The auxiliary ignition means 39 is disposed so that the heat generating portion 391 protrudes from the side wall 11 of the catalyst temperature raising device 1 into the exhaust gas flow path 2, and the heat generating portion 391 is an injection port of the addition valve 31. It is located in the injection direction of the fuel injected from 311.

Further, the auxiliary ignition means 39 is connected to the power supply path 392, and, similar to the ignition means 32, the auxiliary ignition means 39 is energized from the power supply path 392 simultaneously with the start of the engine 8, and the heat generating portion 391 can be heated. It is configured as follows.
Others are the same as in the first embodiment.

In this example, if the fuel injected from the injection port 311 cannot be ignited by the heat generating part 321 of the ignition means 32, it can be ignited by the heat generating part 391 of the auxiliary ignition means 39. Further, when the fuel is ignited by both the ignition means 32 and the auxiliary ignition means 39, the temperature of the catalyst 41 can be raised earlier.
The other functions and effects are the same as those of the first embodiment.

FIG. 3 is an explanatory view showing a place where a catalyst temperature raising device is disposed in the first embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing the structure of a catalyst temperature raising device in Example 1. Sectional drawing of the BB line in FIG. FIG. 3 is an explanatory diagram showing the structure of Comparative Example 1 in Example 2. In Example 2, (a) explanatory diagram showing the fuel injection state, (b) explanatory diagram showing the measurement result of the heat generating part temperature, (c) explanatory diagram showing the measurement result of the catalyst temperature, (d) HC amount Explanatory drawing which shows a measurement result. In Example 3, (a) Explanatory drawing which shows the injection state of fuel, (b) Explanatory drawing which shows the measurement result of heat-emitting part temperature. Explanatory drawing which shows the structure of the catalyst temperature rising apparatus in Example 4. FIG. FIG. 6 is an explanatory diagram showing the structure of a catalyst temperature raising device in Example 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Catalyst temperature rising apparatus 2 Exhaust gas flow path 3 Temperature rising chamber 30 Opening part 31 Addition valve 311 Injection port 32 Ignition means 321 Heat generating part 4 Catalyst support | carrier 41 Catalyst 9 Exhaust gas

Claims (5)

A catalyst temperature raising device for quickly raising the temperature of a catalyst for purifying engine exhaust gas,
The catalyst is built in the exhaust gas passage in a state of being supported on a catalyst carrier,
An upstream side of the catalyst carrier in the exhaust gas flow path has an addition valve having an injection port for injecting fuel, and an ignition means having a heat generating part for igniting the fuel. ,
The catalyst temperature increasing device, wherein the addition valve and the ignition means are disposed at a position where the fuel injected from the injection port directly contacts the heat generating portion.   In Claim 1, the said injection port of the said addition valve is accommodated in the temperature rising chamber which has the opening part opened to the said exhaust gas flow path, and the said addition valve injects a fuel toward the said opening part. The catalyst temperature rising apparatus characterized by arrange | positioning in this way.   3. The catalyst temperature raising apparatus according to claim 2, wherein the heat generating portion of the ignition means is disposed so as to protrude from the temperature raising chamber into the exhaust gas passage through the opening.   4. The catalyst temperature raising apparatus according to claim 2, wherein the temperature raising chamber has a structure in which an opening cross-sectional area gradually decreases as the temperature approaches the opening. In any one of Claims 2-4, when the injection rate of the fuel which the said addition valve injects is q (mm < ³ > / msec) and the opening area of the said opening part is A (mm < ² >), it is 0.49. <= A / q <= 127.6 The catalyst temperature rising apparatus characterized by the above-mentioned.

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