JPH09158715A - Energization control device of electric heating catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the load on the power supply by reducing the supply capability to each EHC in an internal combustion engine in which a plurality of EHCs (catalytic converter) are arranged in an exhaust gas passage. SOLUTION: In an internal combustion engine 1, a plurality of EHCs 4A, 4B provided in series in an exhaust gas passage 2 are connected through switches 5A, 5B, an operational condition parameter detecting means 101 detects the operational condition parameter of the engine, an energization condition judging means 102 judges the energization condition to the EHCs 4A, 4B from the operational condition parameters, an energization time operating means 103 operates the energization time to the EHCs 4A, 4B so that the energization starting time or the energization finishing time of the EHCs 4A, 4B is respectively different when the energization condition to the EHCs 4A, 4B are satisfied, and a switch control means 104 turns on opening/closing switches 5A, 5B for the operated energization time. The energization time operating means 103 may operate the energization time so that the starting of energization to the downstream side EHC 4B is delayed for the prescribed time than that of the upstream side EHC 4A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrically heated catalyst control device, and more particularly to a controller for energizing each electrically heated catalyst when a plurality of electrically heated catalysts are provided in series in an exhaust passage. Regarding the device.

[0002]

Exhaust gas emitted from an internal combustion engine mounted on a vehicle contains harmful substances such as HC (hydrocarbons) and NOx (nitrogen oxides). Is generally provided with a catalytic converter as an exhaust gas purification device for purifying exhaust gas. However, it is known that the three-way catalyst used in this catalytic converter has a low purification rate of harmful substances in exhaust gas when the temperature of the catalyst is low (inactive state). So, for example,
After the cold start of the internal combustion engine, the exhaust gas could not be sufficiently purified in the inactive state of the catalytic converter.

Therefore, a second electrically heated catalytic converter (EHC: Elec) in which an oxidation catalyst is carried and an electric heater is incorporated in an exhaust passage on the upstream side of the catalytic converter.
An exhaust gas purification device that incorporates a trically heated catalyst) and electrically heats the second catalytic converter to activate the oxidation catalyst when the catalytic converter is in an inactive state to accelerate the purification of HC. Proposed.

In an internal combustion engine equipped with such a second catalytic converter (hereinafter referred to as an electrically heated catalyst), a plurality of electrically heated catalysts are arranged in series in an exhaust pipe, specifically, In some cases, the resistance or heat capacity of the upstream side electrically heated catalyst is made different from that of the downstream side electrically heated catalyst so that the plurality of electrically heated catalysts can be uniformly heated and heated (for example, Japanese Patent Application Laid-open No. HEI-HEI-KAI). 6-50135).

[0005]

However, according to the electrically heated catalyst and the method of controlling energization thereof disclosed in JP-A-6-50135, a plurality of electrically heated catalysts are always energized simultaneously when the electrically heated catalyst is heated. Therefore, the load of the power supply such as the battery and the alternator becomes large, and a high-performance, high-capacity battery or alternator is required, which may cause an increase in cost or the battery may deteriorate early. .

In view of the above, according to the present invention, in an internal combustion engine in which a plurality of electrically heated catalysts are arranged in series in an exhaust passage in multiple stages, the electrically heated catalysts are devised by devising the electric conduction to each electrically heated catalyst. An object of the present invention is to provide an electric heating catalyst energization control device capable of simultaneously reducing the power supplied and reducing the load on a power source such as a battery and an alternator.

[0007]

FIG. 1 shows a form of an electrically heated catalyst energization control device of the present invention for achieving the above object. As shown in FIG. 1, the exhaust passage 2 of the internal combustion engine 1 has a plurality of electrically heated catalysts (EH
C) 4A, 4B are connected in series, and each EHC 4A, 4B
Are connected to the power source 6 through the open / close switches 5A and 5B, respectively, and the power is supplied from the power source 6 to the corresponding EHCs 4A and 4B by turning on the open / close switches 5A and 5B. 3A and 3B are ordinary catalytic converters. Thus, the EHC 4 is connected in series to the exhaust passage 2.
In the internal combustion engine 1 provided with A and 4B, in the present invention, the operating state parameter detecting means 101 is the internal combustion engine 1
Of the operating condition parameters of the power supply condition determining means 10
2 is detected according to the engine operating condition parameter
The conditions for energizing C4A and 4B are determined. Then, when the energization time calculation means 103 has satisfied the energization conditions for the EHCs 4A and 4B, the respective EHCs 4A and 4B have different energization start timings or energization end timings.
The energization time to A and 4B is calculated, and the switch control means 104 sets the open / close switches 5A and 5B for the calculated energization time.
Is turned on.

In the energization control device for such EHCs 4A and 4B, the energization time calculating means 103 starts energization to the EHC4B provided on the downstream side of the exhaust passage 2 and starts energization to the EHC4A provided on the upstream side. The energization time may be calculated so as to be delayed by a predetermined time from the time. Further, the energization time calculation means 103 takes in the temperature and load of the engine as shown by the dotted line in FIG. 1, and when the temperature of the engine is below a predetermined value and the load of the engine is below a predetermined value, the downstream side of the exhaust passage 2 The energization time may be calculated so that the energization start to the EHC 4B provided on the upstream side is delayed by a predetermined time from the energization start time to the EHC 4A provided on the upstream side. Further, as shown by the alternate long and short dash line in FIG. 1, the simultaneous heating detection means 105 for detecting the state in which the respective open / close switches 5A and 5B are simultaneously turned on from the output of the energization time calculation means 103, and the engine by taking in the load of the engine And a high load continuation time determination means 106 for detecting whether or not the engine 1 has been continuously operated at a high load for a predetermined time or longer. When the above is continued, the switch control means 104 may turn off the open / close switch 5B connected to the upstream EHC 4A.

According to the electrification control device for the electrically heated catalyst of the present invention, the load on the power source such as the battery can be reduced by reducing the time for simultaneously energizing a plurality of EHCs.
In addition, by delaying the start of energization of the EHC provided on the downstream side of the exhaust passage by a predetermined time from the start time of the energization of the EHC provided on the upstream side, without degrading the temperature raising performance of each of the plurality of EHCs. Thus, the time for simultaneously energizing a plurality of EHCs can be reduced. Furthermore, if the high load operation state of the engine continues for a predetermined time or longer, the upstream EH
By forcibly stopping the energization of C, E on the upstream side
It is possible to prevent the HC from excessively heating due to both exhaust heat and energization heating when the high load operation of the engine is continued.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 is a diagram showing the overall configuration of an internal combustion engine 1 equipped with an embodiment of an electrically heated catalyst energization control device of the present invention.

In FIG. 2, the intake passage 20 of the internal combustion engine 1
Is provided with an air cleaner 23, and an air flow meter 21 and a throttle valve 22 are provided downstream thereof. The air flow meter 21 is provided with an air flow sensor 24 which is a sensor for detecting an intake air amount. A detection value Q of the intake air amount of the air flow sensor 24 is sent to an ECU (engine control unit) 10 as a load amount. Sent.

In the exhaust passage 2 of the internal combustion engine 1, an EHC 4A and an ordinary catalytic converter 3A are provided on the upstream side, and an EHC 4B and an ordinary catalytic converter 3 are provided on the downstream side.
B is provided. Normally, the upstream side has a small capacity and the downstream side has a large capacity in order to improve the warm-up property of the catalyst. On the other hand, a rotation speed sensor 8 for detecting the rotation speed of the internal combustion engine 1 is provided on the output side of the internal combustion engine 1, and in the vicinity of the internal combustion engine 1, the power generation for driving the internal combustion engine 1 to generate electric power. A machine (alternator) 9 is provided. The battery 6 mounted in the vehicle is charged with the electric power obtained by the power generation of the alternator 9. The engine speed Ne detected by the speed sensor 8 and the battery 6
The output voltage Ve of is input to the ECU 10.

In this embodiment, the output terminal of the battery 6 is connected to the upstream side E via a relay 5A which is an open / close switch.
EH on the downstream side connected to the HC 4A via the relay 5B
It is connected to C4B. These relays 5A and 5B are EC
It is designed to be opened / closed by a control signal from U10.
Is energized and heated.

Next, in the energization control device for the electrically heated catalyst of the internal combustion engine having the above-mentioned configuration, the EHC 4A,
The energization control to 4B will be described with reference to the flowcharts shown in FIGS. FIG. 3 shows EHC4 in the present invention.
It is a flowchart which shows the procedure of determination of the energization conditions of A and 4B. This flowchart is executed every predetermined time.

First, in step 301, it is determined whether the internal combustion engine 1 has been started. If the internal combustion engine 1 has been started, the routine proceeds to step 302, where after the terminal voltage Ve of the battery 6 and the engine speed Ne are read, it is determined at step 303 whether the engine speed Ne is at or above a predetermined value. When the engine speed Ne is equal to or higher than the predetermined value in step 303, the routine proceeds to step 304, where it is determined whether the terminal voltage Ve of the battery 6 is between the allowable minimum voltage V2 and the allowable maximum voltage V1. This judgment avoids this condition when the battery voltage is equal to or lower than the predetermined value because the power supplied to the EHCs 4A and 4B is not stable. Conversely, when the battery voltage is equal to or higher than the predetermined value, a high voltage is applied. In order to protect the catalyst by reducing the electric load that occurs when it is applied. The terminal voltage Ve of the battery 6 is the minimum allowable voltage V2 and the maximum allowable voltage V2.
If it is within 1, the process proceeds to step 305.

In step 305, it is judged whether or not there is any abnormality in the diagnosis (abbreviated as "diag" in the figure) such as disconnection detection of the heaters of the EHCs 4A and 4B. If there is no abnormality, the routine proceeds to step 306. Then, in step 306, the flag F for energizing the EHCs 4A and 4B when the flag is 1 is set.
The EHC is set to 1, and this routine ends. On the other hand, if the internal combustion engine 1 has not been started in step 301, the engine speed Ne is smaller than the predetermined value in step 303, the terminal voltage Ve of the battery 6 is lower than the allowable minimum voltage V2 or the allowable maximum in step 304. When it is higher than the voltage V1 and when abnormality is detected in the diagnosis in step 305, the process proceeds to step 307. Then, in step 307, the value of the flag FEHC for energizing the EHCs 4A and 4B is set to 0, and this routine ends.

FIG. 4 shows the EHCs 4A and 4B according to the present invention.
3 is a flowchart showing a control procedure of the first embodiment of the energization control of FIG. In step 401, it is determined whether or not the flag FEHC for energizing the EHCs 4A and 4B is 1. Then, when FEHC = 1, the routine proceeds to step 402, where it is determined whether or not the upstream catalytic converter 3A is in the inactive state. When the upstream catalytic converter 3A is inactive, the routine proceeds to step 403, where it is determined whether the downstream catalytic converter 3B is inactive. This catalytic converter 3A,
The inactive state of 3B can be determined by detecting the temperature of the catalyst with the catalyst temperature sensor, detecting the integrated intake air amount after the start, or by the water temperature of the engine.

When it is determined that FEHC = 0 in step 401, or in step 402, the upstream catalytic converter 3
When it is determined that A is in the active state, the routine proceeds to step 419, where the upstream EHC 4A is de-energized, and at the subsequent step 420, the downstream EHC 4B is also de-energized and this routine ends. When it is determined in step 403 that the downstream catalytic converter 3B is in the active state, the process proceeds to step 420, and the downstream EHC 4B is also in the non-energized state, and this routine ends.

On the other hand, if it is determined in step 403 that the downstream catalytic converter 3B is inactive, step 40
4, the process determines whether the engine 1 is cold before warming up or warm after warming up. First, the control when the engine 1 is cold will be described. When the engine 1 is cold, first, step 405.
In, it is determined whether the engine load is a low load below a predetermined value or a high load above a predetermined value. The engine load is, for example,
It can be determined by the intake air amount (G / N) per engine speed. When the engine 1 is under low load, the routine proceeds to step 406, where the upstream EHC 4A is energized. The energization of the upstream EHC 4A is performed by the ECU 10 turning on the relay 5A.

Then, in the following step 407, the relay 5
The energization time CT1 to A is counted, and in step 408, it is determined whether the energization time CT1 has reached the predetermined time T1. If the predetermined time T1 has not elapsed since the upstream side EHC 4A was energized, this routine is terminated and the predetermined time T
When 1 has passed, the process proceeds to step 409, where the downstream side E
Energize the HC4B. The downstream side EHC 4B is energized by the ECU 10 turning on the relay 5B. Then, in step 410, the count value of the count time CT1 is cleared, and this routine ends.

FIG. 5 (a) shows the energization state to the upstream and downstream EHCs 4A and 4B when such an engine is operated in a cold state at a low load. In this state, the upstream EHC 4A is first energized, and after a predetermined time T1, the downstream EHC 4A is energized.
Energize the HC4B. To stop the energization to the upstream EHC 4A, the flag FE is used in the routine described in FIG.
That is, when HC becomes 0, and when the upstream side catalyst 3A becomes active in step 402. Similarly, to stop the energization to the downstream side EHC 4B, when the flag FEHC becomes 0 in the routine described in FIG. 3, or when the upstream side catalyst 3B becomes active in step 402,
Also, it is when the downstream side catalyst 3B is activated in step 403.

On the other hand, when the engine 1 is cold and under high load operation, the routine proceeds from step 405 to step 411. Then, in step 411, the ECU 10 turns on both the relays 5A and 5B so that the upstream EHC
4A and the downstream side EHC 4B are both energized, and this routine ends. The upstream EHC4A and the downstream E at this time
The energized state of the HC4B is shown in Fig. 5 (b).

Next, the control when the engine is judged to be warm in step 405 will be explained. What is the warm state of the engine?
For example, it is a state where the engine is stopped and restarted for a certain time after the engine is warmed up. At this time, the process proceeds to step 412, and the upstream EHC 4A and the downstream EHC 4B are both energized. Then, in the following step 413, the upstream EHC
4A and the energization time CT2 to the downstream side EHC 4B are counted.

Thereafter, in step 414, it is determined whether the energization time CT2 has reached the predetermined time T2. EH
If the predetermined time T2 has not elapsed since the C4A and 4B were energized, this routine is ended, and if the predetermined time T2 has elapsed, the routine proceeds to step 415, where the upstream EHC4A
Stop the energization. Stopping energization to the upstream EHC4A
This is performed by the ECU 10 turning off the relay 5A.

When step 415 ends, step 41
At 6, it is determined whether the energization time CT2 has reached the predetermined time T3. If the predetermined time T3 has not elapsed since the downstream side EHC4B was energized, this routine is terminated,
When the predetermined time T3 has elapsed, the routine proceeds to step 417, where the energization of the downstream EHC 4B is stopped. Downstream EHC
The power supply to 4B is stopped by the ECU 10 turning off the relay 5B. After this, the count value of step 4108 count time CT2 is cleared and this routine is ended.

FIG. 5 (c) shows the state of energization to the upstream and downstream EHCs 4A and 4B in such a warm state of the engine. In this state, the upstream EHC 4A and the downstream EHC 4
4B is energized at the same time, and when a predetermined time T2 elapses, energization to the upstream EHC 4A is stopped, and when a predetermined time T3 elapses, energization to the downstream ECH 4B is stopped. In addition to this, the power supply to the upstream EHC 4A is stopped at time T2.
Is performed when the flag FEHC becomes 0 in the routine described with reference to FIG. 3 and when the upstream side catalyst 3A becomes active in step 402.
Similarly, when the power supply to the downstream EHC4B is stopped, the time T3
When the flag FEHC becomes 0 in the routine described in FIG. 3 before the elapse of time, when the upstream side catalyst 3B becomes active in step 402, and step 40
In 3 as well, when the downstream side catalyst 3B becomes active.

FIG. 6 is a flow chart showing the control procedure of the second embodiment of the energization control of the EHCs 4A and 4B in the present invention. The second embodiment differs from the first embodiment in that only the control when the engine 1 is operated under high load in a cold state is changed. Therefore, the steps showing the same control as the steps of the control procedure of the first embodiment described in FIG. 4 are given the same step numbers and the description thereof is omitted.

In the first embodiment, when the engine 1 is cold and under high load operation, the ECU 10 turns on both the relays 5A and 5B in step 411 so that both the upstream EHC 4A and the downstream EHC 4B are connected. This routine was finished just by turning on the power. On the other hand, in the second embodiment, when the engine 1 is cold and under high load operation, both the upstream EHC 4A and the downstream EHC 4B are energized in step 411, and then the energization time CT3 is set in step 601. Count.

Then, in step 602, the upstream side E
Energization time to HC4A and downstream EHC4B is a predetermined time T
4 is reached. If the predetermined time T4 has not been reached, this routine is terminated as in the first embodiment, but if the predetermined time T4 has been reached, the routine proceeds to step 603 and the upstream The power supply to the side EHC 4A is stopped. Then, in the following step 604, the counting time CT3 is cleared and this routine is ended.

As described above, when the engine 1 is in the cold state and the high load operation state continues for the predetermined time T4, the upstream side E
The power supply to the HC 4A is stopped because the amount of heat received from the exhaust gas is large during the high load operation of the engine, so that the temperature of the upstream catalytic converter 3A rises quickly and the heater power supply time can be shortened. Further, by shortening the energization time to the upstream side EHC 4A, it is possible to prevent thermal deterioration due to a rise in the catalyst temperature of the catalytic converter 3A.

FIGS. 7 (a) to 7 (e) show the energization states to the upstream and downstream EHCs 4A and 4B when such an engine is operated under high load in the cold state. In this state,
As shown in FIGS. 7 (a) and 7 (b), the upstream EHC 4A and the downstream EHC 4B are energized simultaneously, and as shown in FIG. 7 (c), the load of the engine 1 exceeds the threshold value from the beginning. In the high load operation state, the upstream side E is reached after the elapse of a predetermined time T4.
Stop energizing the HC4A.

On the other hand, as shown in FIGS. 7 (d) and 7 (e), when the engine 1 is initially operated at low load, first, the upstream side E
When only the HC4A is energized at the same time and the engine 1 is under high load operation, the downstream side EHC is shown as shown in FIG. 7 (f).
Energize 4B. Then, when a predetermined time T4 elapses after the engine 1 is in the high load operation state, the upstream EH
Stop energizing C4A.

Stopping the power supply to the downstream EHC4B is shown in FIG.
When the flag FEHC becomes 0 in the routine described in 1), the upstream catalyst 3B becomes active in step 402, or the downstream catalyst 3B becomes active in step 403.

[0034]

As described above, according to the present invention,
It has the following effects. (1) By reducing the time for which a plurality of EHCs are simultaneously energized, the load on the power source such as the battery can be reduced. (2) To decrease the temperature raising performance of each of the plurality of EHCs by delaying the start of energization to the EHC provided on the downstream side of the exhaust passage by a predetermined time from the start time of energization to the EHC provided on the upstream side. Therefore, it is possible to reduce the time for simultaneously energizing a plurality of EHCs. (3) When the engine high load operation state continues for a predetermined time or longer, the upstream EHC is forcibly stopped from energizing, so that the upstream EHC keeps exhaust heat and exhaust heat during the engine high load operation. It is possible to suppress excessive heating by both electric heating.

[Brief description of the drawings]

FIG. 1 is a principle configurational diagram showing a configuration of an electric heating catalyst energization control device of the present invention.

FIG. 2 is a diagram showing the configuration of an internal combustion engine equipped with an embodiment of an electric heating catalyst energization control device of the present invention.

FIG. 3 is a flowchart showing a procedure for determining an energization condition of an electrically heated catalyst according to the present invention.

FIG. 4 is a flowchart showing a control procedure of a first embodiment of energization control of an electrically heated catalyst according to the present invention.

FIG. 5 (a) is a diagram showing the energization state of the upstream side EHC and the downstream side EHC at cold low load in the control procedure of FIG. 4;
Is the upstream EHC at cold high load in the control procedure of FIG.
And (c) is a diagram showing the energization state of the upstream EHC and the downstream EHC during the warm time in the control procedure of FIG. 4.

FIG. 6 is a flowchart showing a control procedure of a second embodiment of energization control of an electrically heated catalyst according to the present invention.

7 is a diagram showing the energization states of the upstream side EHC and the downstream side EHC at the time of a cold high load in the control procedure of FIG. 6 together with the load of the engine, (a) to (c) showing the engine load first. Is a diagram showing the energization state of the upstream side EHC and the downstream side EHC in the case of high load, from (d) ~ (f) is the upstream side EHC when the load of the engine is initially low load and then shifts to high load. And downstream E
It is a figure which shows the electricity supply state of HC.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Exhaust passage 3A, 3B ... Normal catalytic converter 4A, 4B ... Electric heating type catalyst (EHC) 5A, 5B ... Open / close switch (relay) 6 ... Battery 8 ... Rotation speed sensor 9 ... Alternator 10 ... ECU (Engine control unit) 20 ... Intake passage 21 ... Air flow meter 24 ... Air flow sensor 101 ... Operating state parameter detection means 102 ... Energization condition determination means Stage 103 ... Energization time calculation means 104 ... Switch control means 105 ... Simultaneous heating detection means 106 ... High load duration determination means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02D 45/00 360 F02D 45/00 360C (72) Inventor Michio Furuhashi 1 Toyota Town, Toyota City, Aichi Prefecture In Toyota Motor Co., Ltd. (72) Inventor Toshinari Nagai, Toyota City, Aichi Prefecture, 1st Toyota Town, Toyota Motor Co., Ltd. (72) Inventor, Tadayuki Nagai, Toyota City, Aichi Prefecture 1, Toyota Town, Toyota Motor Corporation (72) ) Inventor Takashi Kawai 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Kenji Harima Toyota City, Toyota City, Aichi Prefecture, Toyota City, Toyota (72) Inventor Yuichi Goto Toyota, Aichi Prefecture City Toyota-City, Toyota City

Claims (4)

[Claims] 1. An exhaust gas passage of an internal combustion engine is connected in series with a plurality of electrically heated catalysts each having an electric heater therein, each electrically heated catalyst is connected to a power source through an on / off switch, and each on / off switch is An electrically heated catalyst energization control device that energizes the corresponding electrically heated catalyst from the power source when turned on, the operating condition parameter detecting means detecting an operating condition parameter of the engine, and the detected engine According to the operating state parameter, the energization condition determining means for determining the energization condition to the electrically heated catalyst, and when the electrically energized conditions to the electrically heated catalyst are aligned, the energization start timing of each electrically heated catalyst, or , An energization time calculating means for calculating the energization time to each electrically heated catalyst so that the energization end timings are different, and each of the above-mentioned opening times is calculated only for the calculated energization time. Energization control apparatus of the electrically heated catalyst, characterized in that it comprises a switch control means for the switch to the ON state, the. 2. The electric heating catalyst energization control device according to claim 1, wherein the energization time calculation means starts the energization of the electrically heated catalyst provided on the downstream side of the exhaust passage on the upstream side. An energization control device for an electrically heated catalyst, characterized in that the energization time is calculated so as to be delayed by a predetermined time from an energization start time for the electrically heated catalyst provided in the. 3. The electric heating catalyst energization control device according to claim 2, wherein the energization time calculating means is configured such that when the engine temperature is a predetermined value or less and the engine load is a predetermined value or less,
The energization time is calculated such that the energization start to the electrically heated catalyst provided on the downstream side of the exhaust passage is delayed by a predetermined time from the energization start time to the electrically heated catalyst provided on the upstream side. An electricity control device for an electrically heated catalyst. 4. The electric heating catalyst energization control device according to claim 3, wherein the simultaneous heating detecting means for detecting a state in which the respective opening / closing switches are simultaneously turned on, and the engine being under high load for a predetermined time or longer. Further provided with a high load duration determination means for detecting whether or not it has been operated, in a state where the engine is being heated at the same time, when the high load operating state of the engine continues for a predetermined time or more, the switch An electric conduction control device for an electrically heated catalyst, wherein the control means turns off a switch connected to the electrically heated catalyst on the upstream side.