JP2745867B2 - Catalyst purification device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a catalyst purifying apparatus which has a heater function in a catalytic converter interposed in an exhaust pipe of an internal combustion engine and controls a temperature to a target value.

2. Description of the Related Art Some catalytic converters used for measures against air pollution of automobiles and the like are provided with a heater function for heating the catalytic converter so as to keep the catalyst at a temperature higher than its activation temperature (for example, Japanese Patent Application Laid-Open No. Sho 48-48). -54312). This type of catalyst purification device is divided into a plurality of catalytic converters because the size of the catalytic converter is limited to a certain size or less in terms of structural durability when heating by applying a current to a metallic honeycomb catalytic converter or the like. A first catalytic converter having a heater function in the middle of the exhaust pipe, and control means for heating the first catalytic converter so that the detected temperature of the first catalytic converter is equal to or higher than a target value. It is possible to do.

However, in such an apparatus, although the temperature control of the first catalytic converter having the heater function can be performed accurately, the first catalytic converter having the heater function is provided downstream of the first catalytic converter. It is difficult to properly control the temperature of the second catalytic converter, and there is room for improvement in this regard. For example, even if the temperature of the first catalytic converter rises sufficiently, there is a possibility that the temperature of the second catalytic converter becomes insufficient under operating conditions where the temperature of the exhaust gas is considerably low, so that a sufficient purification performance cannot be obtained as a whole. there were. An object of the present invention is to solve the above points.

SUMMARY OF THE INVENTION The present invention is directed to an exhaust pipe.
When the first catalytic converter with a heater function is interposed
In both cases, the heater unit is located downstream of the first catalytic converter.
Internal combustion engine equipped with a second catalytic converter having no function
Temperature of the second catalytic converter itself
Temperature sensor for detecting the temperature and the detected second catalyst core.
So that the converter temperature becomes the target value.
Control means for heating the heater.

[Function] The temperature sensor measures the temperature of the second catalytic converter itself.
Detected, and based on this detected value,
By controlling the heat, the temperature of the second catalytic converter
It can be managed properly. First touch with heater function
The medium converter temperature is kept higher than the second catalytic converter.
And sufficient purification performance is maintained in total.
You. Moreover, the temperature of the first catalytic converter is
Catalytic converter without heater function located at the bottom
Because there is a correlation with the temperature of the second catalyst converter
Temperature of the first catalytic converter based on the detected temperature
Can be accurately estimated and reflected in the above heating control.
Noh.

Embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the catalyst purification device 1
A case 4 having an inlet 2 and an outlet 3 serves as an exhaust pipe of the engine.
It is connected in the middle and is divided into two in this case 4.
The first and second catalytic converters 5, 6 are arranged in series.
It is interposed. The first and second catalytic converters 5, 6 are:
Wavy metal foil is spirally wound to form many narrow paths
It has a honeycomb structure that consists of
Catalyst metal is carried, and the exhaust gas passing through the narrow path is
Purification by action. First catalytic converter
An insulating mat 8 is interposed between the outer periphery of the
Insulation and heat insulation are performed. In addition, the second catalyst converter
A cushioning material 12 is interposed between the outer periphery of the rotor 6 and the case 4.
Have been. Of the first catalytic converter 5 interposed on the upstream side
The outer peripheral side electrode 9 is connected to the side Rutotomoni, the center
A rod-shaped center electrode 10 is interposed in the portion. The side electrode 9
Positive terminal of battery via lead wire 13 and switch 19
The center electrode 10 is connected via a lead wire 14 to the battery.
Connected to the negative terminal of the battery
The heater 5 has a heater function of electrically heating the heater 5. Soshi
In this embodiment, the temperature of the second catalytic converter 6 itself is
And a temperature sensor 25 for detecting
It is inserted into the center of the two-catalyst converter 6 and provided. This
Thereby, the temperature state of the second catalytic converter 6 is directly
To detect. Second catalyst detected by temperature sensor 25
Converter 6 so that temperature TEHC2 becomes equal to or higher than the target value.
As a control means for heating the first catalytic converter 5,
Control unit for turning ON / OFF switch 19
20 are provided. Control unit 20 is the engine
Input the number of turns and the start switch signal.
For determining a condition for activating the heater function based on the condition
21 and the detection signal TEHC2 of the temperature sensor 25 are input.
Switch based on this to match the target temperature
And a comparison means 22 for turning ON / OFF the 19.
The one catalytic converter 5 is heated. FIG.
The flowchart of FIG.
Shows the control program of the switch 19 to be executed
This is interrupted every fixed time, for example, every 10ms
It is processed. First, in step 2, it is determined whether the engine is rotating.
Judgment, the start switch is turned off in step 3
Is determined after cranking, and
The condition for operating the heater function of the barter 5 is determined. This
In the flowchart of FIG.
5, the temperature of the second catalytic converter 6 detected by
SL # indicates the target temperature. This target temperature is
It is set according to the transfer condition. Basically the second catalytic converter
The detected value TEHC2 of the temperature of the heater 6 is compared with the target temperature TSL #.
In comparison (step 4), the detected value TEHC2 is set to the target temperature.
If higher than TSL #, switch 19 is turned off (step
5) If the detected value TEHC2 is lower than the target temperature TSL #
Switch 19 is turned on to activate the first catalytic converter 5.
Heat (step 6). The temperature sensor 25 is connected to the second catalyst
Detects the temperature of the converter 6 itself, the based on the detection value
By controlling the heating of the single catalytic converter 5, the second
The temperature of the catalytic converter 6 can be properly controlled.
You. The temperature of the first catalytic converter 5 having a heater function is
It is kept higher than the second catalytic converter 6, and the total
As a result, sufficient purification performance is maintained. First catalytic converter
The temperature of 5 has a heater function disposed downstream thereof.
There is no correlation with the temperature of the second catalytic converter 6.
Therefore, the detected value TEHC of the temperature of the second catalytic converter 6
Precisely estimate the temperature of the first catalytic converter 5 based on 2
It is possible, and it is also possible to reflect on the heating control.

As described above, the present invention provides the second catalyst
A temperature sensor is provided to detect the temperature of the converter itself.
The temperature of the second catalytic converter, which has been detected, reaches the target value
With control means to heat the first catalytic converter
Therefore, properly manage the temperature of the second catalytic converter
Can be. Temperature of first catalytic converter with heater function
Is kept higher than the second catalytic converter
And sufficient purification performance is maintained.

[Brief description of the drawings]

FIG. 1 shows the structure of a catalyst purification device according to a first embodiment of the present invention .
FIG.

FIG. 2 is a flowchart illustrating an example of temperature control .
is there.

[Explanation of symbols]

 Reference Signs List 5 first catalytic converter 6 second catalytic converter 9 side electrode 10 center electrode 19 switch 20 control unit 25 temperature sensor

Claims (1)

(57) [Claims] 1. A first contact having a heater function in the middle of an exhaust pipe.
Medium converter and the first catalytic converter
A second catalytic converter without a heater function downstream of the burner
In a catalyst purification device for an internal combustion engine in which a barter is interposed,
Temperature sensor that detects the temperature of the second catalytic converter itself
And the detected temperature of the second catalytic converter becomes the target value.
Control means for heating the first catalytic converter so that
A catalyst purification device for an internal combustion engine, comprising: