JPH0422015Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

<Conventional technology> In internal combustion engines such as diesel engines,
Since the exhaust gas contains many exhaust particulates whose main component is carbon, in order to prevent environmental pollution, the exhaust particulates are collected in the exhaust passage and burned and removed at predetermined intervals. Such a conventional example is shown in FIG. 4 (see Japanese Patent Laid-Open No. 101523/1983).

That is, the exhaust passage 2 of the diesel engine 1
A trap 3 with a catalyst is installed to collect exhaust particulates. Further, an injection valve 4 is provided in the exhaust passage 2 upstream of the catalytic trap 3 to inject and supply light oil, which is engine fuel.

Then, when the exhaust gas temperature is 150° C. or higher, light oil is injected and supplied from the injection valve 4 to the exhaust passage 2 for a predetermined period of time at predetermined intervals.

As a result, HC and CO are supplied into the exhaust gas and flow into the catalyst trap 3 together with the exhaust gas. Then, HC and CO are oxidized in the catalyst-equipped trap 3, and the reaction heat activates the catalyst and burns the exhaust particles, thereby regenerating the trap. Furthermore, instead of light oil, HC or CO may be directly supplied to the exhaust passage.

Note that 7 is an exhaust component analyzer for detecting exhaust components upstream of the catalyst trap 3, which was installed for the purpose of experimentation and is not used in practice.

<Problems that the invention aims to solve> However, in such conventional exhaust particulate treatment devices, light oil, HC, CO, etc. used as engine fuel is supplied to the exhaust passage in order to activate the catalyst. However, these light oils,
The reaction temperature of HC and CO in the catalyst is relatively high. For this reason, even if these diesel oils, HC, and CO are used, the exhaust temperature at which the trap can be regenerated is relatively high (e.g., 300°C or higher), and the operating range where the trap can be regenerated is limited to medium to high speed ranges. Ta.

The present invention was developed in view of the above-mentioned circumstances, and an object of the present invention is to provide an exhaust particulate treatment device for an internal combustion engine that can regenerate traps in a wide range of operating ranges.

<Means for Solving the Problems> For this reason, the present invention includes a first combustible supply device that supplies light oil to the upstream side of a trap with a catalyst installed in an exhaust passage, and a first combustible material supply device that supplies light oil to the upstream side of the trap at a reaction temperature. a second combustible material supply device that supplies a combustible material with a low temperature, a regeneration timing determining means that determines a trap regeneration timing, and detecting an operating state in which the exhaust temperature falls within a temperature range in which the light oil or combustible material can react. an operating state detecting means; controlling the operation of the first combustible supply device when an operating state in which the light oil is in a temperature range where it can react and it is determined that it is time for regeneration; and control means for controlling the operation of the second combustible material supply device when an operating state in the range is detected and it is determined that it is time for regeneration.

<Function> In this way, when the exhaust temperature is relatively high, diesel oil is supplied to the upstream side of the trap, and when the exhaust temperature is low, combustibles, which have a lower reaction temperature than diesel oil, are supplied to the upstream side of the trap. The catalyst is activated from the region where the exhaust gas temperature is low, making it possible to regenerate the trap in a wide range of operating regions.

<Example> An example of the present invention will be described below based on FIGS. 1 to 3.

In the figure, a catalyst trap 13 is installed in an exhaust passage 12 of a diesel engine 11 to collect exhaust particulates. This trap with catalyst 13
is formed of a honeycomb-shaped porous member, and the porous member is coated with an oxidation catalyst.

An injection valve 14 that injects and supplies methanol as a combustible substance to the exhaust passage 12 upstream of the trap with catalyst 13
is provided, and methanol is supplied under pressure to the injection valve 14 from a methanol tank 15 by a pump 16. These injection valves 14 and pumps 16 are configured to be operated and controlled by control signals from a control device 17, which will be described later.

An exhaust gas temperature sensor 18 for detecting exhaust gas temperature is provided in the exhaust passage 12 upstream of the catalyst trap 13, and the detection signal of the exhaust gas temperature sensor 18 is sent to the control device 1.
7 is entered. Furthermore, exhaust pressure sensors 19 and 20 for detecting exhaust pressure are provided on the inlet and outlet sides of the catalyst trap 13, and detection signals from these exhaust pressure sensors 19 and 20 are sent to the control device 1.
7 is entered. Also, methanol tank 1
5 and the pump 16, a passage is connected in the middle of the passage from a fuel tank 21 that stores light oil, which is the fuel for the diesel engine 11, and an electromagnetic three-way valve 22 is provided at the connection part of these passages. There is. This electromagnetic three-way valve 22 is configured to be switched and controlled by a control signal from the control device 17 so as to supply either methanol or light oil to the pump 16.

The control device 17 determines that it is time to regenerate the trap when the differential pressure across the catalyst trap 13 is equal to or higher than a predetermined value. When the controller 17 determines that it is time to regenerate the trap, it switches the electromagnetic three-way valve 22 according to the temperature detected by the exhaust temperature sensor 18 to supply either methanol or light oil to the pump 16. Specifically, as shown in Figure 2, the exhaust temperature is
In the operating range of 200 to 300°C, methanol is supplied to the trap with catalyst 13, and in the operating range of 300 to 500°C, light oil is supplied to the trap with catalyst 13.

Therefore, the control device 17 constitutes a regeneration timing determination means and a control means, and the control device 17 and the exhaust gas temperature sensor 18 constitute an operating state detection means. Further, the injection valve 14, the pump 16, the fuel tank 21, and the electromagnetic three-way valve 22 constitute a first combustible supply device, and the injection valve 14, the methanol tank 15, the pump 16, and the electromagnetic three-way valve 22 constitute a second combustible material supply device. Configure a combustible material supply device.

Next, the action will be explained.

When the differential pressure across the catalyst trap 13 is less than a predetermined value, the control device 17 determines that the amount of exhaust particulates collected is small and the trap is not regenerating, and stops the operation of the injection valve 14 and pump 16. Exhaust particles discharged from the engine flow into the catalyst trap 13 via the exhaust passage 12 and are collected therein. At this time,
When the exhaust temperature is high, the exhaust particles are collected in the catalyst trap 13 and are self-combusted by the exhaust heat, thereby regenerating the catalyst trap 13. Here, in a trap equipped with a catalyst, the exhaust temperature is between 400 and 500.
Self-combustion treatment of exhaust particulates becomes possible at temperatures above ℃ (catalyst activation temperature), and in models without a catalyst, this becomes possible when the exhaust temperature is approximately 600℃ or above.

Then, when the differential pressure across the catalyst trap 13 exceeds a predetermined value, the control device 17 determines that it is time to regenerate the trap. Furthermore, when the control device 17 determines that it is time to regenerate the trap, the exhaust temperature detected by the exhaust temperature sensor 18 is within a predetermined range (for example, 200
℃ to 300℃). When the predetermined range is reached, the control device 17 controls the operation of the injection valve 14 and the pump 16 to release methanol into the exhaust passage 12.
A substantially constant amount of injection is supplied to the

As a result, methanol is transferred to the catalyst trap 13.
However, as shown in Figure 3, methanol has a lower reaction temperature than light oil (usually 20 to 50 degrees Celsius lower), so even if the exhaust temperature is relatively low, methanol undergoes an oxidation reaction in the catalyst trap 13. and develops a fever. Therefore, the temperature inside the catalyst-equipped trap 13 rises, so that the catalyst is activated, and the exhaust particles are burned by the catalytic action, so that the catalyst-equipped trap 13 can be regenerated.

In addition, in the operating range where the exhaust temperature is 300 to 500℃,
The electromagnetic three-way valve 22 is switched to open the fuel tank 21.
of light oil is injected into the exhaust passage 12 via the pump 16 and the injection valve 14. As a result, the light oil is introduced into the trap 13 with a catalyst and burns to generate heat, activating the catalyst, so that the trap 13 with a catalyst can be regenerated. As a result, the exhaust temperature is approximately
Since exhaust particulates can be stably burned and removed at temperatures above 200°C and the trap can be regenerated, the trap can be regenerated in a wider range of operation than the conventional method.

At this time, the exhaust temperature when methanol is injected and supplied is set at 200 to 300 degrees Celsius, and diesel oil, which is the engine fuel, is used in the operating range above this, so methanol consumption can be significantly reduced. The replenishment interval to the tank 15 can be significantly lengthened.

Note that the methanol injection amount and the light oil injection amount may be changed depending on the exhaust temperature and exhaust flow rate. Also,
Although the exhaust gas temperature is directly detected by the exhaust temperature sensor 18, the state of the exhaust gas temperature may be searched from an exhaust temperature map set based on the engine rotational speed and the engine load. Furthermore, the mounting position of the exhaust gas temperature sensor 18 is not limited to the upstream side of the catalyst trap 13. Furthermore, the present invention can also be applied to traps that do not have a catalyst. <Effects of the invention> As explained above, the present invention supplies light oil to the upstream side of the trap when the exhaust temperature is relatively high, and supplies combustibles with a lower reaction temperature than light oil when the exhaust temperature is low. As a result, exhaust particulates can be stably removed by combustion at a lower exhaust temperature than before, trap regeneration can be performed over a wider range of operation than before, and the consumption of combustibles can be suppressed to shorten the replenishment interval of combustibles. You can make it longer.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
The figure is an explanatory diagram of the same operation as above, FIG. 3 is a diagram showing the relationship between exhaust temperature and conversion rate for methanol and light oil, and FIG. 4 is a configuration diagram showing a conventional example. 12... Exhaust passage, 13... Trap with catalyst,
14...Injection valve, 16...Pump, 17...Control device, 18...Exhaust temperature sensor.

Claims (1)

[Scope of utility model registration request] A trap for collecting particulates in the exhaust gas is interposed in the exhaust passage of the engine, and a first combustible material supply device supplies light oil to the upstream side of the trap, and a combustible material whose reaction temperature is lower than that of light oil is provided to the upstream side of the trap. a second combustible material supply device for supplying a trap, a regeneration timing determining means for determining a trap regeneration time, and an operating state detecting means for detecting an operating state in which the exhaust gas temperature falls within a temperature range in which the light oil or combustible material can react. and when an operating state in which the light oil is in a temperature range where it can react is detected and it is determined that it is time for regeneration, the first combustible substance detection device is actuated and controlled, and the operation is in a temperature range in which the combustible substance can react. An exhaust particulate treatment device for an internal combustion engine, comprising: control means for controlling the operation of the second combustible material supply device when a state is detected and it is determined that it is time for regeneration.