JPS5985417A - Minute particle removing apparatus for diesel engine - Google Patents

Abstract

PURPOSE:To raise the temperature of exhaust gas above the natural temperature of minute particle by installing an electrical heater on the upstream side of a collector member installed in the exhaust passage of a Diesel engine and controlling the amount of exhaust gas which passes through the electrical heater by the control valves installed in intake and exhaust passages. CONSTITUTION:The collector member 11 of a trapper 10 for collecting minute particles is installed in the exhaust passage 9 of a Diesel engine 1, and an electrical heater 12 is arranged at a departed position on the upstream side of the collector member 11. A bypass passage 13 equipped with a control valve 14 is arranged in parallel onto the trapper 10, and the control valve 14 is closed in the ordinary operation. At the regeneration time for the collector member 11, a controller 17 puts the electrical heater 12 into conduction through a relay 19 and adjusts the opening degree of a throttle valve 4 to a prescribed position. Then, the throttle bypass control valve 14 is controlled so that the temperature of exhaust gas becomes above the natural temperature of minute particle and below the fusing temperature by the temperature sensors 20 and 21 before and behind the collector member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to regeneration of a trapper provided in an exhaust passage of a diesel engine.

Exhaust gas discharged from a diesel engine is passed through a trapper installed in the exhaust passage, and particulates such as soot (hereinafter referred to as particulates) contained in the exhaust gas are made of a ceramic porous body of the trapper. It is collected by a collection material.

Particulates accumulate in the trapper over time, increasing pressure loss and increasing engine output loss, so once particulates have accumulated to a certain extent,
It is necessary to incinerate the particulates and regenerate the trapper.

Conventionally, particulates are combusted mainly by bringing an electric heater into contact with the collection material and directly igniting the particulates with the electric heater. It is also known that a method of heating the exhaust gas passing through an electric heater to a temperature higher than the particulate self-combustion temperature is also effective.

Among these methods, in the method of heating exhaust gas, the exhaust gas temperature is relatively low in the low-speed operation range, so even if the temperature is raised with an electric heater, it is difficult to raise the temperature above the self-combustion temperature of the particulates. If the operating range is not met, there is a problem in that exhaust gas that is heated to a sufficiently high temperature necessary for trapper regeneration cannot be obtained. Of course, as you tighten the throttle, the exhaust gas will become hotter due to richer combustion, but drivability may deteriorate due to excessive throttle, and if you tighten the intake throttle, the amount of oxygen required for combustion for regeneration will increase. The problem arises that there is a shortage of That is, in the conventional method of heating exhaust gas and burning and removing particulates with the heated exhaust gas, there has been a problem that regeneration over the entire operating range cannot be performed.

The present invention heats particulate exhaust gas to produce particulate matter.
The purpose of this invention is to enable regeneration in the entire operating range in regenerating a trapper that burns fuel.

In order to achieve this object, in the diesel particulate removal device of the present invention, the electric heater is provided upstream of the trapping material of the trapper without contacting the trapping material. Also, in the intake and exhaust passages, there is a throttle valve in the intake passage,
At least one of the bypass valves provided in the bypass passage of the trapper is provided, and this valve functions as a control valve that adjusts the flow rate of exhaust gas passing through the electric heater. A control valve consisting of at least one of a throttle valve and a bypass valve is connected to a computer (hereinafter referred to as ECU), and the ECU:
A signal for controlling the flow rate of exhaust gas passing through the electric heater is sent to the control valve so that the exhaust gas passing through the electric heater becomes higher than the particulate self-combustion temperature. However, the exhaust gas inlet temperature and exhaust gas outlet temperature of the trapper's collection material are detected and the signal is E.
Sent to CU.

In the above device, at least one of the thrower 1 to the bypass valve is controlled by the ECU, so that the exhaust gas input temperature of the collection material is equal to or higher than the particulate self-combustion temperature, and the exhaust gas output wetness is controlled by the ECU. Controlled below the collection material melting temperature.

In other words, under the control of the ECU, the heating by the electric heater works organically with the gas flow rate of the entire diesel engine system, making it possible to raise the exhaust gas above the particulate self-combustion temperature in the entire operating range. Trapper playback becomes possible.

Preferred embodiments of the diesel particulate removal device of the present invention will be described below with reference to the drawings.

FIG. 1 shows a system of an apparatus according to an embodiment of the present invention. In the figure, 1 is the main body of the diesel engine, 2 is the intake manifold, 3 is the intake passage, 4 is the throttle valve provided in the intake passage 3, 5 is the diaphragm that operates the throwers 1 to 4, and 6 is the vacuum to the diaphragm 5. 7 is a vacuum switching valve (hereinafter referred to as VSV) that adjusts the opening degree of the throttle valve 4 by turning it on and off, and 7 is a throttle sensor that detects the opening degree of the throttle valve 4. Further, 8 is an exhaust manifold, 9 is an exhaust passage, and 10 is an exhaust manifold.
is a trapper provided in the exhaust passage 9.

The trapper 10 has inside thereof a collection material 11 made of a porous ceramic material or the like. The trapper 10 includes a collection material 1
An electric heater 1 is installed on the upstream side of 1 and away from the collecting material 11.
2 is provided. The electric heater 12 is not for igniting particulates in close contact with the collection material 11 as in the conventional case, but for heating the exhaust gas passing through the electric heater 12.

A bypass passage 13 that bypasses the trapper 10 is arranged in parallel with the trapper 10, and a bypass valve 14 that throttles the bypass passage 13 is provided in the bypass passage 13. Bypass valve 14 is actuated by a diaphragm 15, which is actuated by negative pressure from a vacuum pump. A vacuum switching valve (hereinafter referred to as VSV) 16 is provided in the negative pressure passage to the vacuum pump, and a bypass valve 14 is provided.
Adjust the opening.

V for operating the electric heater 12 and the throttle valve 4;
SV6, VSV16 that operates the bypass valve 14,
Each is electrically connected to ECtJ17. Of these, a battery 18 and a relay 19 are provided in the circuit connecting the electric heater 12 and the ECU 17.
9 is closed by a signal from the ECU 17 and the battery 18
A current is passed through the electric heater 12 to energize the electric heater 12.

The ECU 17 is comprised of components that perform the functions shown in the flow diagram of FIG. That is, first, it is determined whether it is playback time or not. Whether it is time to regenerate or not is determined by integrating the engine rotation speed and determining whether the engine rotation speed exceeds a certain rotation speed (for example, 150,000 rotations). When it is determined that it is time for regeneration, the electric heater 12 is energized. The current is relay 19
This is done by turning on.

Next, the opening degree of the throttle valve 4 is adjusted.

This is done by activation of VSV6. The throttle opening degree is adjusted so that the throttle valve 4 is closed to an allowable angle depending on operating conditions such as engine speed and load conditions. In this case, the throttle opening degree is measured by the thrower 1 to the throttle sensor 7. When the throttle opening is adjusted, the opening of the bypass valve 14 is adjusted, and the collection material 1
The temperature of the exhaust gas to 1 is the particulate combustion temperature T+
(for example, 400°C) or below, and the temperature T at which the wetness of the exhaust gas from the collection material 11 does not cause the collection material 11 to melt.
2 (for example, 600° C.) or less, the IJI gas flow rate passing through the electric bee 912 is controlled. The exhaust gas human temperature T1 is measured by a temperature sensor 20 provided between the collection material 11 and the electric heater 12, and the exhaust gas stagnation degree T2 is measured by a temperature sensor 21 provided at the outlet of the collection material 11. be done. In this state, normal combustion of particulates, that is, regeneration of the trapper 10 is performed. Trapper 10
When the time T3 considered necessary for regeneration has elapsed, the bypass valve 14 is closed, the throttle valve 4 is closed, and the electricity to the electric heater 12 is turned off, thereby completing the regeneration. The above series of regeneration operations are controlled and commanded by the ECU 17.

In the above embodiment, the regeneration is performed by operating both the throttle valve 4 and the bypass valve 14.
Regeneration may be performed by providing only one of the bypass valve 14 and the bypass valve 14 and controlling it.

Figure 3 shows EECU1 when the intake throttle is used only.
7 functions are shown in a flow diagram. In this case, when the electric heater 12 is energized and the throttle valve 4 is turned on, the ECU 17 adjusts the opening of the throttle valve 4 so that the temperature of the exhaust gas passing through the electric heater 12 falls between T1 and T2. Electric P91 to become
The two-pass exhaust gas flow rate is controlled. When the regeneration time T3 has elapsed, the throttling is turned off and the electric heater 12
is turned off and playback ends. The ECL 117 is configured to sequentially perform this series of playback operations.

Also, Figure 4 shows the EC when the exhaust throttle is used only.
The function of U17 is shown in a flow diagram. In this case,
When the electric heater 12 is energized, the bypass valve 14 is opened and its opening degree is adjusted, and the flow rate of the exhaust gas passing through the electric pipe 912 is adjusted so that the wetness of the exhaust gas passing through the electric heater 12 is between T1 and T2. is controlled. Playback time T3
After , the bypass valve 14 is closed, the electric heater 12 is de-energized, and the regeneration is completed. EC
U17 is configured to perform this series of playback operations in order.

Note that in each of the above embodiments, the collecting material 11 may be a collecting material that is the same as the catalyst.

A platinum-based catalyst such as PT or PD is used as the catalyst, and these catalysts have the function of lowering the regeneration temperature and shortening the regeneration time.

Next, the effects of each of the above implementations will be explained.

First, since the bypass valve 14 is normally closed, exhaust gas discharged from the diesel engine main body 1 is discharged through the trapper 10, and when passing through the trapper 10, particles such as soot in the exhaust gas are removed. Curates are collected.

When particulates accumulate and it is time for regeneration, the ECU
Reproduction under the control of 17 is started.

The electric heater 12 heats the exhaust gas to a temperature equal to or higher than the particulate combustion temperature T1, and when this heated exhaust gas passes through the collection material 11, it touches the particulates and ignites them, thereby cooperating with the self-combustion of the particulates. It works to burn and remove particulates. therefore,
The electric heater 12 does not ignite the particulates by direct contact with the particulates;
Exhaust gas is heated, and particulates are combusted by the heated exhaust gas.

Combustion of particulates is carried out under the control of E and CL117 in all operating ranges including low speed operating ranges. Furthermore, since the ECU 17 controls the flow rate of exhaust gas passing through the electric heater 12 while taking into consideration the operating conditions of the diesel engine, problems such as deterioration of drivability and lack of oxygen due to particulate combustion will not occur in the entire operating range. . In addition, during combustion under the control of the ECU 17, the outlet temperature of the collecting material 11 is also detected and controlled.
No melting loss occurs.

As explained above, in the diesel particulate removal device of the present invention, the electric heater heats the exhaust gas and the heated exhaust gas burns the particulates, and the ECU controls the flow rate of the exhaust gas passing through the electric heater to control the operating conditions. Since the exhaust gas temperature is controlled in consideration of the above, the present invention makes it possible to regenerate the trapper in all operating ranges, including low-speed operating ranges, without deteriorating drivability. You can get the effect that you can. Note that if a collector with a catalyst is used, the regeneration of the trapper can be further facilitated.

[Brief explanation of the drawing]

Fig. 1 is an overall system diagram of the diesel particulate removal device of the present invention, Fig. 2 is a flow diagram showing the functions of the ECU of the device of Fig. 1, and Fig. 3 is an ECLI diagram of another embodiment of the present invention. FIG. 4 is a flow diagram showing functions of an ECU according to still another embodiment of the present invention. 1... Diesel engine body 3...
...Intake passage 4...Throttle valve 6...
...VSV 7...Throttle sensor 9...
...Exhaust passage 10...Trapper 11...Collection material 12...Electric heater 13...・Bypass passage 14... Bypass valve 16...
...VSV 17... Computer (ECU) 18.
......Battery 19...Relay 20.21...Temperature sensor Figure 2 Figure 3 Procedure amendment December 8, 1982 Commissioner of the Japan Patent Office 1. Indication of the case Patent Application No. 195336 of 1982 2. Title of the invention Diesel particulate removal device 3. Relationship with the person making the amendment Patent applicant address Name Toyota Motor Corporation 4 , agent 〒
107 Address: 1-7-5 Akasaka, Minato-ku, Tokyo @ Showa Building Column 7 of the detailed description of the invention in the specification, Contents of amendment (1) Changed “electric heater” in the third line of page 3 of the specification to “ Correct the intake throttle or exhaust throttle. (2) Set the "exhaust throttle" on page 10, line 3 of the specification to 1 bypass bar 94

Claims (2)

[Claims] (1) A trapper provided in the exhaust passage of a diesel engine is provided with an electric heater upstream of the collection material, and a control valve is provided in the intake/exhaust passage of the diesel engine to adjust the flow rate of exhaust gas passing through the electric heater, The electric heater and the control valve are connected to a computer, and the computer controls the flow rate of the exhaust gas passing through the electric heater in order to heat the exhaust gas passing through the electric heater to a temperature higher than the self-combustion temperature of the particulates when the electric heater is energized. A diesel particulate removal device characterized by having the function of (2) The diesel particulate removal device according to claim 1, wherein the control valve is comprised of at least one of a throttle valve provided in an intake passage and a bypass valve provided in a bypass passage of the trapper.