JPH05202740A - Electric heating catalyst controller - Google Patents

Abstract

PURPOSE:To reduce the discharge quantity of HC and CO in the unburnt gas immediately after the start of an engine by means of an electric heating catalyst, temperature detecting means which detects the temperature of this electric heating catalyst, control means which controls conductive current, and power supply means which takes out current independently supplied to the electric heating catalyst. CONSTITUTION:The unburnt gas exhausted by an internal combustion engine 1 is discharged outside after passing through a front catalyst 2 and through a main catalyst 3. The front catalyst 2 is constituted of a temperature sensor 6 and terminal 7. This terminal 7 is connected to a battery 4 and engine controller 5. This engine controller 5 comprises a transistor 11 and control circuit 12 receiving signals sent from the temperature sensor 6, and the control circuit 12 generates duty drive signals to the base of the transistor 11. An independent battery 15 is provided with a dedicated battery charger 14. When a key switch 13 is turned ON, the temperature of the front catalyst 2 reaches the set value, heating the catalyst. Therefore, when the engine is started, the adverse composition such as HC and CO in the unburnt gas is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst device suitable for use in purifying exhaust gas from an automobile engine.

[0002]

2. Description of the Related Art A conventional electric heating catalyst control device is
A E, Technical, Paper, Series, 900503
(1990) Item 61 to Item 70 (SAE, Technical, Pa
per, Series, 900503 (1990) Page.61-70), a catalyst composed of a resistor-type metal carrier is heated by applying an electric current to the exhaust gas at low temperature. It states that it can improve performance.

[0003] Such electrically heated catalysts can be heated to about 350 within 30 seconds using a conventional 12V power system.
It is designed to reach a catalyst activation temperature of ° C. These control means are provided with catalyst heating current supply means and catalyst temperature detection means so that the temperature can be raised to a desired catalyst operating temperature.

However, since the amount of electric power required to heat the catalyst is about 4.7 KW, a considerable electric load is applied to the conventional power source, resulting in discharge and deterioration of the power source. Connect In addition, in order to minimize exhaust gas pollution, it is desirable that the catalyst is heated prior to starting the engine so as to approach the catalyst activation temperature when starting the engine. As a result, the charging ability of the power source is deteriorated, and it becomes difficult to start the engine by the starter.

The present invention is to solve the above problems. A first object of the present invention is to ensure starting of an engine by making an engine starting power source independent from a power source for supplying a current to the electrically heated catalyst. A second object of the present invention is to increase the transmission efficiency as a power source by using a voltage higher than that of the engine starting power source for the independent power source. As a result,
It is possible to realize a low cost, small size and lightweight power supply control device.

[0006]

In the above-mentioned prior art, no consideration is given to the power supply for supplying the current to the catalyst, and if the charge capacity of the battery decreases, it becomes difficult to drive the starter used when starting the engine. There was a problem that the engine could not be started. Therefore, an object of claim 1 of the present invention is to increase the efficiency of purifying the gas by heating the catalyst temperature and reduce the amount of HC and CO emissions in the gas before it is supplied with a power supply for supplying a current to the catalyst. Is independent of the power source for engine control to ensure engine startup and control. Further, an object of claim 2 of the present invention is to provide a control device which is low in cost and lightweight in order to improve power transmission efficiency by making the independent power source equal to or higher in voltage than an engine control power source. Is. Further, an object of claim 3 of the present invention is to accelerate the purification of gas which is released immediately after the engine is started by heating the catalyst before the engine is started. The object of claim 4 of the present invention is that the activation temperature of the catalyst is 350 ° C.
Since it is in the vicinity, the heating target temperature of the catalyst is set to 350 ° C., which prevents unnecessary power consumption. An object of claim 5 of the present invention is to provide a method for efficiently heating and controlling an electrically heated catalyst in a short time. This makes it possible to rapidly heat the catalyst, and by controlling the temperature, unnecessary power can be prevented. The object of claims 6 and 7 of the present invention is to provide a charging means and a charging control of this power source by providing a power source independent of the engine. An AC / DC converter or an alternator is used as a charger. This allows downsizing and saves space on the vehicle. An object of claim 8 of the present invention is to charge an independent power supply by the AC / DC converter after the engine has been started so that it does not become a load on the engine control power supply when it is charged by the AC / DC converter. It is a consideration. An object of claim 9 of the present invention is to provide a charge control means for charging with an AC / DC converter. As a result, unnecessary charging / discharging can be eliminated and the life of the power supply is not deteriorated. The object of claim 10 of the present invention is to arrange the electrically heated catalyst at a position upstream of the exhaust gas with respect to the conventional main catalyst, so that the heat of the exhaust gas can be received, and the required power of the electrically heated catalyst can be obtained. It is possible to reduce the amount. The object of claim 11 of the present invention is to install the current control means for the electrically heated catalyst in the engine control device, which makes it possible to save the space as the control device, which is advantageous in vehicle installation.

[0007]

The electrocatalyst control device of the present invention is intended to achieve the above-mentioned object. The means are a catalyst that is heated by the passage of an electric current, and a catalyst for heating the electrocatalyst. The temperature detection means for detecting the temperature, the control means for controlling the energization current of the electrically heated catalyst, the power source independent of the engine control power source, and the charging means for charging the power source independent of the engine control power source are provided. Can be achieved.

[0008]

According to the structure of the electrocatalyst control device of the present invention described above, the temperature is detected by the temperature detecting means of the catalyst and the current is passed through the catalyst by the controlling means to heat the catalyst before the engine is started. Therefore, the efficiency of purifying the gas can be increased immediately after the engine is started, and the amount of HC and CO emissions in the gas can be reduced. Further, by setting the power supply voltage for supplying the current to the catalyst higher than the power supply voltage for starting the engine, it is possible to suppress the current flowing to the catalyst to be low, which reduces the weight of wiring, downsizes the control device, and improves power transmission efficiency. Can be improved.

[0009]

Embodiment 1 Embodiment 1 of the present invention will be described below with reference to FIG.

FIG. 1 is a conceptual block diagram showing the overall structure. First, the unexposed gas exhausted from the internal combustion engine 1 passes through the front catalyst 2 and the main catalyst 3 which is larger in volume than the front catalyst
Is released to the outside air via The front catalyst 2 includes a temperature sensor 6 for detecting the temperature of the catalyst and two terminals 7 for supplying an electric current.
An electrically heated catalyst (EHC) described in SAE Paper (900503). In the embodiment of the present invention, (EHC) is shown as the precatalyst. However, when there is more than one (EHC) precatalyst with respect to the main catalyst, or when both the precatalyst and the main catalyst are (EHC). Is also applicable. One of the two terminals 7 for supplying current is the battery 4 and the other terminal 7 is an engine controller (EC
U) 5 is connected to the collector of the transistor N-P-N11. Although not shown in FIG. 1, the engine control device 5 includes a transistor 11 for generating an EHC control signal, which controls switching of relay means for ON / OFF control of a current to the front catalyst 2, and a temperature sensor 6. The control circuit 12 receives a signal. As a result, the control circuit 12 generates a duty drive signal for the base of the transistor 11. The emitter of the transistor 11 is connected to the negative terminals of the batteries 4 and 15. On the other hand, the battery 4 is a conventional 12V battery connected to the alternator 8, the starter motor 9, and the electric load 10.
The ignition switch 13 is connected between the control circuit 12 and the battery 4.

With respect to the present invention, the independent battery 15 preferably has a voltage equal to or higher than that of the battery 4, for example, 24V, and the charger 14 dedicated to this battery 15 is provided. The charger 14 may be an alternator other than the engine control alternator, a three-phase transformer and an AC / DC converter as shown in FIG. The battery 15 is separated and independent of the battery 4 except for the ground line.

Next, the operation will be described based on the above-mentioned overall structure. When the key switch 13 is turned on, the control circuit (ECU) 5 equipped with a microcomputer outputs a preset catalyst temperature set value (about 350 ° C.) to a command value,
Feedback control is performed using the signal of the temperature sensor 6 as a feedback value. In this way, the control circuit 12 controls the duty of the base of the transistor 11 so that the temperature of the front catalyst 2 approaches the set value. As a result, when the temperature of the precatalyst 2 reaches 350 ° C., the transistor 11 for stopping the current supply for heating the precatalyst 2 is turned off.
The current supplied according to the ON duty of the transistor 11 is the battery 15, the front catalyst 2, the transistor 11
And then generate heat due to the electric resistance value of the precatalyst 2. Therefore, if the engine is started by the battery 4 and the starter motor after the heating of the catalyst is completed, the efficiency of purifying the gas of the catalyst is sufficiently high, and harmful components such as HC and CO contained in the gas are significantly increased. It can be removed. In addition, even if the charge amount of the second independent battery 15 is reduced due to being consumed for heating the front catalyst 2, the drive battery 4 of the starter motor for starting the engine will be changed to the battery 15 for heating the catalyst.
Since it is independent from, there is no difficulty in starting the engine.

Next, with reference to FIG. 2, a battery charging circuit and an electrocatalyst heating circuit will be described with reference to the first embodiment of the present invention.

In FIG. 2, the ignition switch 1
3 is connected in series with the ignition warning light 21 and in parallel with the ballast resistor 22. The ignition warning light 21 is connected to an IC regulator 23 built in the alternator 8. The alternator 8 constitutes a Y connection of the stator for outputting a three-phase AC output. The three-phase AC output of the stator 24 is normally rectified to 12V by the diode 25 and supplied to the electric load 10 and the battery 4. Usually, the induction coil 26 is installed as a known built-in circuit between the positive terminal of the battery and the regulator 23. With respect to the present invention, the three-phase AC output from the stator coil is connected to the charger 14, 12V to 2V in the embodiment of FIG.
It is boosted to 4V by the three-phase transformer 27 and sent to the AC / DC converter 28. As shown in FIG. 2, the battery 15
Is a 24V battery in which two 12V batteries are connected in series. It supplies power to (EHC) 2, and AC / D
It is charged by connecting to the C converter 28. The stator 24 and the three-phase transformer 27 are connected via a relay 31 controlled by a (ECU) 5 through a line 32. Then, by this (ECU) 5,
4V battery 15 charging can be selectively turned ON / OFF at any time
Controlled by. The voltage of the battery 15 is (EC
U) 5 monitored via line 33. The output of the temperature sensor 6 is also monitored by the (ECU) 5 via line 34. Furthermore (ECU) 5
Transmits the (EHC) energization control signal through the line 35 to the sub relay 36 installed to selectively transmit the switching signal to the main relay 37. The main relay 37 has a battery 15 for (EHC) 2.
It is a relay for switching the current of about 250 amps from, and is a high current compatible relay.

As shown in FIG. 1, the (EHC) control circuit 12 is preferably built in the engine control device 5, but as shown in FIG. 3, it is independent of the engine control device 5. The control circuit 300 can be simply used.
It may be placed inside.

Next, FIG. 3 will be described.

The (EHC) control circuit 12 has an OR gate 3
01, and receives input signals of the starter motor 9 and the engine speed signal (Ne). The OR gate 301 is
An output signal indicating whether the operating condition of the starter motor 9 or a predetermined engine speed is reached is transmitted to the engine start completion judging means 302. From 302 to line 3
2, the AC / D also depends on the output states of the means 303 and 304 for determining the charging voltage of the battery 15.
A signal for controlling the operation of the C converter control relay 31 is transmitted. Here, 304 is a means for determining whether the charging voltage of the battery 15 is lower than a predetermined target voltage, and 303 is whether the charging voltage of the battery 15 is equal to or higher than the predetermined target voltage. Is a means for determining.

Next, the temperature detected by the temperature sensor 6 becomes an input signal of the warm-up completion temperature determination means 305 of (EHC), and when it is lower than a predetermined target temperature, (EHC)
The output signal is transmitted to the (EHC) current control relays 36 and 37 via the (HC) control signal line 35. At this time,
This output signal is, of course, also determined depending on the output signals of 303 and 304, whether or not transmission is possible.

Although the ignition switch 13 is a conventional one, it has at least three stages of positions, and is a power-off position separated from all so-called electric loads from the so-called battery 4, and then a power-on position ( The so-called key switch is turned on), and finally the induction coil 26 for driving the starter motor 9 is energized to start the engine.

When the power ON position is reached for the first time after the ignition switch is turned off, this is judged by the power ON position judging means 306, and if it is judged ON, the engine start completion judging means 302
A connected to receive an engine stop determination signal (meaning so-called engine OFF state) sent from A
The ON determination output signal is transmitted to the ND gate 307.
When these two signals are both input, AND gate 3
07 outputs an output signal to the (EHC) current control relays 36 and 37, and outputs an output signal to the (EHC) preheat possibility determination means 308.

Next, the operation of each relay will be described.

When the engine start completion determining means 302 determines that the engine start is completed, the charging voltage of the battery 15 is equal to or exceeds a predetermined target value.
When the determination is made at 303, the AC / DC converter control relay 31 is turned off to cut off the charging line of the battery 15. Then, the (EHC) control signal is turned on to turn on the (EHC) current control relays 36 and 37 in order to supply the electric power from the battery 15 to the (EHC) 2. If the voltage of the battery 15 is lower than a predetermined target value and the engine has already started, the AC / DC converter 28 to the line 29.
The ON signal for turning on the AC / DC converter control relay 31 for charging the battery 15 via
Output from 04. Further, at this time, the relay 36 for controlling the relay 37 is turned off (EHC) to control OF.
F By effectively utilizing the determination results of the means 303 and 304, if the voltage of the battery 15 is sufficient, it is possible to save power by not operating the AC / DC converter 28, while the battery 1
When the power of 5 is extremely reduced, the power supply to the front catalyst 2 is stopped.

Since it is desirable that the front catalyst 2 be preheated before the engine is started, when the engine stop state is detected and an input is made to the AND gate 307, and the ignition switch is in the power ON position,
Means 308 based on the determination results of the means 303, 304
Outputs a command signal for turning on the (EHC) current control relays 36, 37.

Next, the control timing of each control will be described with reference to FIGS. 4 (a) to 4 (g). (EHC)
The temperature of 2 is usually outside temperature (for example, 25 ° C), and (EH
The optimum operation of C) is about 350 ° C as shown in Fig. 4 (a).
Is. As shown in FIG. 4B, if the ignition switch 13 is in the power ON position of the first position (so-called key switch ON) and the engine is still stopped, the line 35 ( The EHC) control signal is output from the means 308 as an ON signal. Next, if necessary, the operation of determining the voltage of the battery 15 determined by the means 303 and 304 may be ignored so that the operation steps described below are not performed.

As shown in FIG. 4C, as soon as the (EHC) control signal is turned on, the battery 15 supplies electric power for heating the precatalyst 2. When the temperature of the front catalyst 2 reaches about 50 ° C. (the required time is about 6 to 10 seconds), the ignition switch 13 then activates the starter motor 9 (as shown in FIG. 4D). It is set so that a signal for driving can be issued. With the rotation of the starter motor, the engine also starts to rotate, and as a result, the alternator 8 also starts to rotate. When the starter motor is rotated, the engine also starts to rotate, and the alternator rotation speed also gradually increases. After that, when the start of the engine is completed, the starter motor is stopped. Starter motor is ON to O
When the FF is performed (or, although not shown, when the engine speed detected by the rotation sensor reaches a predetermined value, the control signal of the AC / DC converter is transmitted from the means 302 via the line 32 from the means 302 ( 4 (f) is switched from OFF to ON, and the state of the relay 31 is controlled according to the output signals from the means 303 and 304. If the battery 15 If the voltage is low or lower than a predetermined target value, the relay 31 is turned on, and the charger including the three-phase transformer 27 and the AC / DC converter (see FIG. 4 (f))
A charging operation is performed via line 29 to charge the 24V battery 15 (as shown in FIG.

The charger 14 has an AC / DC converter 28.
However, the charger 14 may be another well-known alternator or the second output of a twin rotor / twin stator alternator.

[0027]

EFFECTS OF THE INVENTION According to the present invention, even if the charge capacity of an electrically heated catalyst battery is lowered due to catalyst heating, it can be recalled that the amount of electric power is about 4.7 kW. Since it is independent of the catalyst heating battery, it is possible to avoid problems such as reduced capacity and difficulty in starting the engine. Further, since the catalyst is heated to raise the temperature before the engine is started to improve the efficiency of purifying the gas, the amount of HC and CO emissions in the gas immediately after the engine is started can be significantly reduced. Furthermore, by using a high-voltage independent power supply, the current consumption can be reduced, which makes it possible to downsize the components, reduce the overall weight, and increase the power transmission efficiency. This has the effect of being able to provide the above control device.

[Brief description of drawings]

FIG. 1 is a conceptual block diagram showing an overall configuration of a catalyst control device according to a first embodiment of the present invention.

FIG. 2 is a conceptual block diagram showing a power supply charging circuit and a heating circuit for an electrically heated catalyst proposed this time in relation to the first embodiment of the present invention.

FIG. 3 is a diagram showing a flow of control states of the present invention.

4 (a) to (g) show timing diagrams of the operation of the control device of the present invention. In each drawing, reference numerals indicate the related numbers of each component, component, means, and the like.

[Explanation of symbols]

1 ... Engine, 2 ... Front catalyst (electrically heated catalyst), 3 ... Main catalyst, 4 ... Battery, 5 ... Engine control device, 6 ... Temperature sensor, 7 ... Connection terminal, 8 ... Alternator, 9 ... Starter, 10 ... Electricity Load, 11 ... Transistor, 12 ... Control circuit, 13 ... Key switch, 14 ... Charger, 15 ... Battery for heating front catalyst (electrically heated catalyst), 21 ... Warning lamp, 22 ... Ballast resistor, 23 ... Regulator, 2
4 ... Stator, 25 ... Diode, 26 ... Induction coil, 27 ... Three-phase transformer, 28 ... AC / DC converter.

Claims (11)

[Claims] 1. An exhaust gas purifying apparatus for an engine, wherein an exhaust gas purifying catalyst for the engine is arranged in an exhaust passage of the engine, and an electrically heated catalyst that is heated by being energized with an electric current, and an electrically heated catalyst for the electrically heated catalyst. A temperature detecting means for detecting a temperature, a control means for controlling a current flowing through the electrically heated catalyst, and a control means for instructing the temperature of the electrically heated catalyst to approach a predetermined set temperature by a signal from the temperature detecting means. And an electric heating catalyst control device for purifying exhaust gas of an internal combustion engine, comprising: an electric power supply means for taking out a current supplied to the electric heating catalyst independently of an engine control power supply. 2. The electric heating according to claim 1, wherein a power supply for supplying a current to be supplied to the electric heating catalyst has a voltage equal to or higher than that of a power supply for engine control. Catalyst control device. 3. The control means for controlling the energization current of the electrically heated catalyst starts the control operation before the engine is started, according to claim 1 or claim 2. The electric heating catalyst control device described. 4. A predetermined set temperature of the electrically heated catalyst is set to 35.
The electric heating catalyst control device according to claim 1, wherein the temperature is set to 0 ° C. 5. The control means for controlling the energizing current of the electrically heated catalyst has a control circuit means which is activated by an ignition switch of an engine and is connected to a temperature detecting means for detecting the temperature of the electrically heated catalyst. The control circuit means includes a comparing means for comparing the temperature detected by the temperature detecting means with a predetermined temperature, and a switching device for controlling the supply of the energizing current of the electrically heated catalyst based on the comparison result. The electrically heated catalyst control device according to claim 1, wherein the electrically heated catalyst control device is configured. 6. The electric heating catalyst control device according to claim 5, wherein the power source means independent of the engine control power source is charged by an AC / DC converter. 7. The electric heating catalyst control device according to claim 5, wherein the power source means independent of the engine control power source is charged by an alternator. 8. The control means for controlling a current flowing through the electrically heated catalyst is an AC / DC power source means independent of the engine control power source after the engine has been started.
The electrically heated catalyst control device according to claim 5, further comprising a determination unit that determines whether or not the connection operation of the converter is started. 9. A control means for controlling a current flowing through the electrically heated catalyst comprises means for determining a voltage level of a power supply means independent of the engine control power supply, and the voltage level is higher than a predetermined voltage level. When the voltage is low, the switching device is turned on to connect the AC / DC converter to a power source means independent from the engine control power source for charging, and when the voltage level is equal to or higher than a predetermined voltage level, the switching device 6. The electric heating catalyst control device according to claim 5, wherein the AC / DC converter is turned off to disconnect the AC / DC converter from a power supply unit independent of the engine control power supply. 10. The electric heating catalyst control device according to claim 1, wherein the electric heating catalyst having a resistance element for guiding a power source for heating the catalyst is arranged upstream of the main catalyst. 11. The electric heating catalyst control device according to claim 1, wherein the control means for controlling the energization current of the electric heating catalyst is incorporated in the engine control device.