JPH0322503Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a diesel particulate exhaust treatment device, and in particular, to a diesel engine exhaust gas treatment device suitable for capturing combustible particles in diesel engine exhaust gas and burning them to regenerate a filter member. A filter member arranged in a gas flow path to collect particulate matter in the exhaust gas, and a heater arranged close to an end of the filter member in the exhaust gas inflow direction to ignite and burn the particulate matter. The present invention relates to an improvement of a diesel particulate exhaust treatment device equipped with a member.

[Conventional technology]

Recently, diesel engines have come into widespread use as vehicle engines due to their good fuel efficiency. However, diesel engines contain carbon (soot) and carbonization generated due to incomplete combustion in their exhaust gas. It contains diesel particulate (hereinafter simply referred to as particulate) made of hydrogen (HC) and the like, and if this is released into the atmosphere together with exhaust gas, it is not desirable because it will pollute the atmosphere. For this reason, it is necessary to provide an exhaust treatment device in the exhaust flow path for collecting and re-burning particulate matter contained in the exhaust gas, and a number of these techniques have been proposed in the past. That is, JP-A-57-
No. 210114 is characterized in that a filter member for collecting particulate matter is provided in the exhaust gas flow path to collect the particulate matter in the exhaust gas, and the collected particulate matter is appropriately burned to regenerate the filter member from clogging. An exhaust treatment device for purifying exhaust gas has been proposed. However, in the above-mentioned exhaust treatment device, when the filter member is regenerated, if the engine speed is high, the flow velocity of the exhaust gas becomes high, and the fire ignited in the particulate is blown out. Furthermore, since the filter members are packed in close contact with each other, the heat of the combustion part is absorbed by the adjacent filter members, which often causes the temperature of the combustion part to drop and the fire to go out. Therefore, it has not been possible to sufficiently restore the function of the filter member that has become clogged due to the particulate matter. Various proposals have already been made to solve these problems. As one such method, for example, Japanese Patent Laid-Open No. 59-49825 proposes a method of lowering the ignition point of diesel carbon black discharged from the exhaust gas of a diesel engine. This involves loading a special catalyst on a filter that traps carbon black, or particulate matter, to lower the ignition point and allow the filter to be regenerated without consuming additional fuel. Also, for example, JP-A-59
-93916, a diesel engine exhaust gas purification device is proposed. By delaying the fuel injection timing of the diesel engine during specific vehicle operating conditions, this system sends the activated exhaust gas containing large amounts of carbon monoxide and hydrocarbon compounds to a filter equipped with an oxidation catalyst, thereby reducing the temperature of the filter. The aim is to increase the combustibility of particulate by raising the temperature.

[Problem that the invention attempts to solve]

However, when a vehicle equipped with a diesel engine is driving in an urban area, the exhaust gas temperature thereof is low. Therefore, the above-mentioned JP-A-59-
49825 and the device proposed in JP-A-59-93916, the temperature of the end face of the filter member in the device in the exhaust gas inflow direction decreases with the temperature of the exhaust gas. However, it is difficult to ignite the collected particulate by energizing an electric heater. Therefore, when the filter member of the device is regenerated, the electric heater has to consume a large amount of electric energy.

[Purpose of invention]

The present invention was devised in view of the above-mentioned conventional problems, and the present invention provides a diesel putty that can obtain good ignitability for the collected particulate even if the exhaust gas emitted by the diesel engine is at a low temperature. The purpose of the present invention is to provide an exhaust gas treatment device.

[Means to solve the problem]

The present invention includes a filter member disposed in an exhaust gas flow path of a diesel engine to collect particulate matter in the exhaust gas, and a filter member disposed close to an end of the filter member in the exhaust gas inflow direction. , a diesel particulate exhaust treatment device comprising a heater member for igniting and burning the particulate, the preheating filter disposed on the exhaust gas upstream side of the heater member for assisting in the ignition and combustion of the particulate; a catalyst that reacts with unburned components in the exhaust gas, and a fuel of the diesel engine to increase the unburned components of the exhaust gas before energizing the heater member to ignite and burn the particulate. The above object is achieved by including a fuel injection timing delay means for delaying the injection timing. Further, in an embodiment of the present invention, the fuel injection timing delay means delays the fuel injection timing prior to energizing the heater member when the integrated value of the number of revolutions of the diesel engine reaches a certain value. Specifically, the filter member is periodically regenerated. Furthermore, in another embodiment of the present invention, when the heater member is energized, a bypass passage that bypasses the filter member is opened, so that the particulate is stably ignited and burned.

[Effect]

The diesel engine particulate exhaust treatment device according to the present invention processes exhaust gas by collecting particulate matter in the exhaust gas with a filter member. In addition, the diesel engine particulate exhaust treatment device appropriately ignites and burns the collected particulate by energizing a heater member for igniting the collected particulate in order to maintain the exhaust gas processing ability. Regenerate the filter member that has become clogged. On the other hand, the diesel particulate exhaust treatment device delays the fuel injection timing of the diesel engine using a fuel injection timing delaying means before energizing the heater member. Then, the unburned components in the exhaust gas increase, and the unburned components react with the catalyst in the preheating filter disposed upstream of the heater member to generate heat. Therefore, the temperature of the exhaust gas on the downstream side of the preheating filter increases, and the temperature of the exhaust gas itself also increases due to afterburning due to unburned components, so the temperature of the filter member that collects the particulates increases, and the particulates Ignition and combustion become easier. Therefore, the filter member can be regenerated well, and the amount of electric power to be applied to the heater member can be reduced, which is economical.

【Example】

Examples to which the present invention is applied will be described in detail below. The present embodiment relates to a diesel engine particulate exhaust treatment device that is used by being connected to the exhaust system of a diesel engine 10, as shown in FIG. In the figure, exhaust gas discharged from a diesel engine 10 flows into a turbocharger 14 through a manifold 12. The turbocharger 14 is for compressing intake air of the diesel engine 10 to increase output. Exhaust gas discharged from the turbocharger 14 flows into an exhaust treatment device 16. The exhaust treatment device 16 collects particulates of exhaust gas and processes them by igniting and burning them. Further, there is provided a bypass valve 18 that bypasses most of the exhaust gas so that the entire amount of the exhaust gas does not pass through the particulate filter 22 when igniting and burning the particulate. The exhaust gas that has flowed out from the exhaust treatment device 16 is discharged into the atmosphere, and thus flows out into an exhaust system path (not shown). Note that 13 is an EGR valve of an exhaust gas recirculation device that processes a portion of exhaust gas and recirculates it to the intake system. As shown in detail in FIG. 2, the exhaust treatment device 16 includes a preheating filter 20 for preheating a particulate filter 22, which carries a catalyst that generates heat by reacting with hydrocarbons in the exhaust gas, and a particulate filter 20 for preheating a particulate filter 22. An electric heater 24 that ignites particulate matter and a particulate filter 22 that collects particulate matter are arranged along the flow direction of the exhaust gas. Note that the preheating filter 20 is configured with a filter that has a small heat capacity and a small wind pressure loss of the exhaust gas. On the other hand, the diesel engine 10 is provided with a water temperature sensor 26 for detecting the coolant temperature C, a rotation sensor 28 for detecting the engine rotation speed N, and a load sensor 30 for detecting the load F applied to the engine. Further, on the inlet side of the exhaust treatment device 16, an exhaust temperature sensor 32 is installed to detect the temperature G of exhaust gas. Furthermore, the water temperature sensor 2
6, the output signal N of the rotation sensor 28, the output signal F of the load sensor 30, and the output signal G of the exhaust temperature sensor 32, a fuel injection timing signal T is sent to the fuel injection pump 34. An electronic control unit (hereinafter abbreviated as ECU) is used to output
36 are provided. The ECU 36 includes a vacuum switching valve (hereinafter referred to as VSV) that switches an operation signal H to an electric heater relay 38 for passing current to the electric heater 24 and a negative pressure circuit 19 for driving the bypass valve 18. (abbreviated) 40 and the fuel injection pump 41
This outputs a signal T to control the fuel injection timing. In addition, 42 is a vacuum pump which forms the negative pressure supplied to the negative pressure circuit 19 switched by the said VSV40. Also, 44 is the VSV4
0 is an actuator that transmits turning on and off by the drive signal V to the bypass valve as a drive force. The effects of the embodiment will be explained below. In this embodiment, as shown in FIG. 3, first in step 110, when the diesel engine 10 is in operation, the engine rotation speed N is determined by the output of the rotation sensor 28, the engine load F is determined by the output of the load sensor 30, and the water temperature sensor 2
Input the cooling water temperature C of the 6 output and the exhaust gas temperature G of the exhaust gas temperature sensor 32 output. Next, the program proceeds to step 112, where it is determined whether the integrated value of the engine speed N has reached a constant value _N0 . If the determination result is positive, that is, if it is determined that the integrated value has reached a certain value, the process proceeds to step 114, where it is determined whether the cooling water temperature C exceeds 60°C.
If the judgment result is positive, that is, the cooling water temperature is 60℃
If it is determined that the exhaust gas temperature G has exceeded 600°C, the process proceeds to step 116, where it is determined whether the exhaust gas temperature G has exceeded 600°C. If the determination result is negative, that is, if it is determined that the exhaust gas temperature G does not exceed 600°C, the process proceeds to step 118, and the ECU 36 outputs a signal T to the fuel injection pump 41 to delay the fuel injection timing. Therefore, the diesel engine starts delaying or retarding the fuel injection timing. When the retardation starts, the amount of unburned parts, especially hydrocarbons (HC) increases in the exhaust gas of the diesel engine. Then, the hydrocarbon reacts with the catalyst in the preheating filter 20 to generate heat, and the preheating filter 20 heats the exhaust gas. At this time, the downstream particulate filter 22 is preheated by the heated exhaust gas. Next, step
Proceeding to step 120, 30 seconds after the start of the retard is a time for preheating the particulate filter 22 by the preheating filter 20, so the retard time t
count. Furthermore, if it is determined that the count value exceeds 30 seconds after proceeding to step 122,
Proceeding to step 124, a signal V for opening the bypass valve 18 is output to the vacuum switching valve 40, and an activation signal H is output to the electric heater relay 38 for causing current to flow through the electric heater 24, so that the electric heater A current flows through 24. The time for which the current flows is set so that each electric heater 24 is energized for 30 seconds. Next, step 126
Then, it is determined whether all the electric heaters 24 have been energized. If the determination result is positive, the process proceeds to step 128, where the bypass valve 18 is gradually closed over 30 seconds, and the retardation is also completed. Note that if the determination results in steps 112, 114, 122, and 126 are negative, or if the determination results in step 116 are positive, the process returns to step 110. step 128
After finishing, the diesel engine 10
The injection timing returns to normal, and the exhaust gas is also collected by the particulate filter 22. In this embodiment, the fuel injection timing is retarded when the integrated value of the rotation speed N of the diesel engine reaches a certain value, so the particulate filter 22 is periodically regenerated. Therefore, particulate matter in exhaust gas can be collected stably. Further, in this embodiment, the particulate filter 2
When igniting the patty cubes collected in step 2,
By opening the bypass valve 18 and slowing down the flow rate of the exhaust gas through the particulate filter 22, the ignitability of the particulate is improved, and the fuel is well spread throughout the particulate. In the above implementation, the fuel injection timing was retarded by the ECU 36, but the control device is not limited to this, and other devices may be used.

[Effect of the idea]

As explained above, in the present invention, when regenerating the filter member, the exhaust gas is heated by the preheating filter and the filter member is preheated.
It becomes easier to ignite the particulate by the heater member. Therefore, it is possible to reduce the amount of electric power to be applied to the heater member, which has an excellent effect of improving economical efficiency.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main parts, including a partial block diagram, showing the configuration of a diesel engine in which an embodiment of the diesel particulate exhaust treatment device to which the present invention is applied, and FIG. FIG. 3, an enlarged sectional view showing the internal structure of the embodiment in detail, is a flowchart for explaining the operation of the embodiment. 10... Diesel engine, 16... Exhaust treatment device, 20... Preheating filter, 22... Particulate filter, 24... Electric heater, 36...
Electronic control unit (ECU), 41...Fuel injection pump.

Claims (1)

[Claims for Utility Model Registration] (1) A filter member disposed in the exhaust gas flow path of a diesel engine that collects particulate matter in the exhaust gas, and an end portion of the filter member in the exhaust gas inflow direction. In a diesel particulate exhaust treatment device including a heater member disposed in close proximity to ignite and burn the particulate, there is provided a heater member disposed on the exhaust gas upstream side of the heater member for assisting in igniting and burning the particulate. a preheating filter; a catalyst supported on the preheating filter that reacts with unburned components in the exhaust gas; 1. A diesel particulate exhaust treatment device comprising: fuel injection timing delay means for delaying fuel injection timing of the diesel engine. (2) Registration of a utility model in which the fuel injection timing delay means delays the fuel injection timing prior to energizing the heater member when the integrated value of the number of revolutions of the diesel engine reaches a certain value. A diesel particulate exhaust treatment device according to claim 1. (3) The diesel particulate exhaust treatment device according to claim 1, wherein a bypass passage that bypasses the filter member is opened when the heater member is energized.