JP2833376B2 - Electric control device for electrothermal catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric control device for an electrothermal catalyst.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional power supply control device for an electrothermal catalyst (EHC) of this type (see, for example, Japanese Utility Model Laid-Open No. 63-67609).

That is, the exhaust passage 10 of the engine 101
2 includes an electrothermal catalyst 1 close to the upstream side of the main catalyst 103.
04 is installed. An electric heater is embedded in the electrothermal catalyst, and one electrode 105 for energization is provided on the center line of the electrothermal catalyst 104, and the catalyst outer frame 106 is used as the other electrode. A temperature sensor 107 is provided on the catalyst outer frame 106, and a detection signal of the temperature sensor 107 is transmitted to the controller 1
08 has been entered. The output of the temperature sensor 107 detects that the catalyst has warmed and been activated, and the power supply to the electrothermal catalyst is stopped.

[0004]

However, in such a conventional electrothermal catalyst energization control device, when the electrothermal catalyst is operated at a very low temperature when the charge amount is insufficient due to deterioration of the battery or the like, There is a problem that electric power is taken by the electrothermal catalyst, the cranking speed is reduced, and the startability is deteriorated.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electric control device for an electrothermal catalyst which prevents deterioration of startability.

[0006]

According to the present invention, there is provided a power supply control device for an electrothermal catalyst which heats a catalyst for purifying exhaust gas to accelerate the activity of the catalyst .
Based on the water temperature at the start, the lower the water temperature, the lower the value.
Means for calculating a setting voltage electrothermal catalyst energized with a composed such characteristics, means for comparing the said set voltage and the battery voltage, and means for detecting the engine start, the provided is greater than the battery voltage is above the set voltage only when, and so as to energize the heating catalyst after engine startup.

[0007]

[Function] Power supply to the electrothermal catalyst is started after the engine is started.
The startability is not reduced and the battery voltage starts.
If it is lower than the set voltage corresponding to the operating water temperature,
The power is not supplied even after the
Is suppressed. Here, if the starting water temperature is low,
Exhaust emissions are relatively poor, but the set voltage
Is low when the starting water temperature is low.
Even if the battery voltage is low to some extent, electricity is supplied to the electrothermal catalyst
This means that the catalyst is activated early. Against this
However, if the starting water temperature is high, the set voltage will increase,
Priority is given to battery protection.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG.
FIG. 3 to FIG. 3 are diagrams showing one embodiment of the present invention.

First, the configuration will be described with reference to FIG. 1 is an engine, 2 is an exhaust passage, and 3 is an electrothermal catalyst, which is installed close to the upstream side of the main catalyst 4. 5 based on the engine coolant temperature from the voltage value and the water temperature sensor 7 of the battery 6 by engine control unit, means 5a, the set voltage V ₀ and a battery for calculating an electric catalyst energizing set voltage V ₀ which in its operating condition A means 5b for comparing the voltage V and a means 5c for detecting start are provided.

Reference numeral 8 denotes a power supply unit for supplying electric power of the battery 6 to the electrothermal catalyst 3 in accordance with a signal from the engine control unit 5. 9 is a battery voltage warning light, 1
0 is an air cleaner, 11 is a throttle valve, and 12 is a combustion injection valve.

Next, the control operation will be described with reference to the flowchart of FIG. In FIG. 2, the electrothermal catalyst 3 is represented as EHC.

First, the apparatus is operated by the starter signal.

In step S1, it is determined whether or not the engine is in a cranking state. If it is during cranking, the process proceeds to step S2. If the cranking is completed and the start detecting unit 5c detects the start, the process proceeds to step S9.

In step S2, the voltage V of the battery 6 is read, and in step S3, the engine cooling water temperature is read from the water temperature sensor 7.

[0015] Then, it calculates the electric catalyst energizing set voltage V ₀ based on the battery voltage V and the water temperature in step S4 the setting voltage calculation unit 5a.

Here, the lower the water temperature at the start, the lower the battery
Electricity to the electrothermal catalyst (EHC) 3 is allowed with the re-voltage V
As it will be, as shown in FIG. 3, the set voltage V ₀ which electrothermal catalyst 3 is set so that the water temperature at the starting time becomes lower as lower.

In step S5, the battery voltage V read in step S2 is replaced with the set voltage V calculated in step S4.
_If the battery voltage V is greater than the set voltage V _{0, the} process proceeds to step S6 to turn on the EHC (Electrothermal Catalyst) flag. If the voltage V is smaller, the process proceeds to step S7, and the EHC flag is set to OF.
F, the warning light 9 is turned on in step S8 to warn the driver.

In step S9 with the engine started, it is determined whether or not the EHC flag is ON.
If the HC flag is ON, the process proceeds to step S10 to energize the electrothermal catalyst 3 to accelerate the activity of the catalyst.

If the EHC flag is OFF, the process proceeds to step S11 without supplying power to the electrothermal catalyst 3, and waits for the battery voltage to increase.

As described above, the startability is properly ensured by determining whether or not to energize the electrothermal catalyst 3 after starting the engine.

Thereafter, the control operation described above is repeated, and the control operation is stopped after the catalyst is activated.

[0022]

As described above, according to the present invention, when the charge amount is insufficient due to the deterioration of the battery or the like, the electric heating catalyst is not energized, so that the good startability can be obtained. can get.

Also, the lower the water temperature at the start, the higher the set voltage
Low, so immediately after cold start, the battery voltage
Even though the current is allowed to be low, the activity of the catalyst
Premature, worse exhaust emissions during cold start
Can be suppressed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an outline of a configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a control operation of the embodiment.

FIG. 3 is a set voltage V ₀ for energizing the electrothermal catalyst in the same embodiment.
FIG. 3 is a diagram showing a change in water temperature at the time of starting.

FIG. 4 is a diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Exhaust passage 3 ... Electrothermal catalyst (EHC) 4 ... Main catalyst 5 ... Engine control unit 6 ... Battery 7 ... Water temperature sensor 8 ... Power supply device

Claims (1)

(57) [Claims] An electric power control device for an electrothermal catalyst which heats a catalyst for purifying exhaust gas to accelerate the activity of the catalyst, comprising: a means for detecting a water temperature at the time of engine start ;
Means for calculating a setting voltage electrothermal catalyst energized with a characteristic such as the water temperature becomes lower the lower the value, means for comparing the said set voltage and the battery voltage, and means for detecting the engine start, the provided, only when the battery voltage is greater than the set voltage, electrification control apparatus of the electric heating catalyst, characterized in that so as to energize the heating catalyst after engine startup.