JP2007321718A - Exhaust emission control catalyst preheating method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure purification performance, when starting an engine at the low temperature, by properly preheating a catalyst 3, even if the catalyst 3 is deteriorated a little. <P>SOLUTION: A deterioration state of the catalyst 3 is detected, and the target temperature of the catalyst 3 is set in response to the deterioration state. When predicting starting of the engine, preheating of the catalyst 3 is started so that the catalyst 3 becomes the target temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a catalyst preheating method and an apparatus for exhaust gas purification of an engine.

    In recent exhaust gas purification catalysts for engines, a purification rate of 95% or higher is obtained at high exhaust gas temperatures, but improvement of the purification rate at low temperatures including when the engine is started remains as a problem. In order to solve the problem, for example, a catalyst converter is directly connected to the exhaust manifold of the engine, and measures such as early activation of the catalyst by heat of exhaust gas or improvement of low temperature activity of the catalyst are taken.

For example, as described in Patent Document 1, the catalyst is preheated before the engine is started, that is, when the driver inserts a door key, when the door is opened, the driver is seated on the seat. When the engine key is inserted into the key cylinder, a technique for starting heating of the catalyst by the heater is also known.
JP-A-5-202737

    When preheating the catalyst as described above, it is desirable to heat the catalyst so that the exhaust gas can be purified immediately and efficiently even when the engine is started at a low temperature. However, if the catalyst is used for a long period of time, even if the catalyst is preheated before the engine is started, the purification performance that is expected immediately after the engine is started will not be exhibited. It is known that the catalyst deteriorates as its use period becomes longer, because the light-off temperature of the catalyst increases due to the deterioration.

    Therefore, an object of the present invention is to ensure the purification performance at the time of starting the engine at a low temperature even if the catalyst is somewhat deteriorated.

    In the present invention, the catalyst is appropriately preheated according to the deterioration state of the catalyst in response to such a problem.

The invention according to claim 1 is an exhaust gas purifying catalyst preheating method provided in an exhaust passage of an engine,
Detecting a deterioration state of the catalyst;
Setting a target temperature of the catalyst according to the deterioration state of the catalyst;
Predicting the start of the engine;
And a step of starting preheating of the catalyst so that the catalyst reaches the target temperature when the start of the engine is predicted.

    Therefore, according to the present invention, the catalyst can be preheated to a temperature suitable for exhaust gas purification according to the deterioration state of the catalyst, and even when the engine is started at a low temperature regardless of some deterioration of the catalyst. Therefore, the expected purification performance can be secured immediately.

    The deterioration state of the catalyst can be detected based on, for example, the amount of oxygen used for purifying exhaust gas by the catalyst during engine operation. In this case, it is determined that the deterioration of the catalyst progresses as the amount of oxygen used per unit time decreases. Such oxygen usage can be determined from the difference between the oxygen concentration of the exhaust gas flowing into the catalyst and the oxygen concentration of the exhaust gas flowing out of the catalyst. Alternatively, the deterioration state of the catalyst can be detected (determined) based on the travel distance of the vehicle or the operating time of the engine. In this case, the target temperature is increased when the catalyst is deteriorated, but it is preferable to increase the target temperature as the deterioration proceeds.

The invention according to claim 2 is the invention according to claim 1,
An oxygen sensor for detecting the oxygen concentration of the exhaust gas is provided upstream or downstream of the catalyst in the exhaust passage,
When the start of the engine is predicted, there is provided a step of starting preheating of the oxygen sensor before starting the preheating of the catalyst, simultaneously with the start of the preheating, or after the start of the preheating.

    That is, it is known that it is preferable to control the oxygen concentration of the exhaust gas flowing into the catalyst by controlling the air heat ratio of the engine in order to make the catalyst work effectively for purifying the exhaust gas. In order to appropriately control the oxygen concentration, it is necessary to provide an oxygen sensor for detecting the oxygen concentration of the exhaust gas upstream or downstream of the catalyst. However, the performance of this oxygen sensor also depends on temperature, and when the sensor temperature is low, accurate air-fuel ratio control cannot be performed. Therefore, in the present invention, the catalyst is preheated and the oxygen sensor is also preheated so that the catalyst can be operated efficiently immediately after the engine is started.

The invention according to claim 3 is the invention according to claim 1 or claim 2,
The engine is a vehicle driving engine,
When the occupant who drives the vehicle approaches the vehicle to a predetermined distance, preheating of the catalyst is started on the assumption that the start of the engine is predicted.

    Therefore, it is advantageous in securing a sufficient preheating time and heating the catalyst to a predetermined temperature before the engine is started.

The invention according to claim 4 is the invention according to claim 3,
When the time from when the occupant approaches the vehicle to a predetermined distance until the door of the vehicle opens is longer than a predetermined time, preheating of the catalyst is stopped.

    That is, even if the passenger approaches the vehicle, the engine is not always started. Therefore, even if the occupant approaches the vehicle, when the time until the vehicle door opens is long, the preheating of the catalyst is stopped to minimize waste of energy.

The invention according to claim 5 is any one of claims 1 to 4,
When the start of the engine is predicted, when the temperature of the catalyst is equal to or higher than a predetermined temperature, the start of preheating of the catalyst is delayed.

    That is, when catalyst preheating is started when the catalyst temperature is relatively high, the catalyst temperature can be quickly raised to the target temperature. However, when the time until the subsequent engine start is long, it is necessary to use extra energy in order to maintain the catalyst temperature. Even if the engine is predicted to start, the engine may not be started after that. Therefore, by delaying the start of preheating when the catalyst temperature is high, energy consumption is minimized, and unnecessary preheating when the engine is not started can be avoided.

The invention according to claim 6 is any one of claims 1 to 5,
A battery for supplying electric power for starting the engine;
If the remaining capacity of the battery is equal to or less than a predetermined value at the time when the engine is predicted to start, preheating of the catalyst by the power of the battery is prohibited.

    That is, when the remaining capacity of the battery is small, the engine may not be started by preheating the catalyst. Therefore, in the present invention, to preferentially start the engine, when the remaining battery capacity is low, preheating of the catalyst by the electric power of the battery is prohibited.

The invention according to claim 7 is a catalyst heating means for heating the exhaust gas purifying catalyst of the engine;
Catalyst temperature detecting means for detecting the catalyst by measuring or estimating the temperature of the catalyst;
Catalyst deterioration state detecting means for detecting the deterioration state of the catalyst;
Means for setting a target temperature of the catalyst according to the deterioration state of the catalyst detected by the catalyst deterioration state detection means;
Means for predicting the start of the engine;
When the start of the engine is predicted, the catalyst heating means is operated to start raising the temperature of the catalyst so that the catalyst is brought to the target temperature based on the temperature detected by the catalyst temperature detecting means. And a catalyst preheating control means for raising the temperature of the exhaust gas purifying catalyst.

    Accordingly, the deterioration state of the catalyst is detected during engine operation, the target temperature of the catalyst is set in accordance with the deterioration state of the catalyst, and when the engine is predicted to start, the catalyst becomes the target temperature. Thus, even if the engine is started at a low temperature, the expected purification performance can be ensured regardless of some deterioration of the catalyst.

    As the catalyst temperature detecting means, a thermocouple that directly measures the temperature of the catalyst can be employed, or, for example, an elapsed time after starting the engine (engine operating time) or after the engine is stopped. The catalyst temperature may be estimated based on the elapsed time (engine stop time) and the outside air temperature and / or the engine water temperature. By detecting the catalyst temperature, it is possible to reliably raise the temperature of the catalyst to the target temperature. In addition, the catalyst temperature after the start of preheating can also be calculated | required based on energy consumption, such as a battery, or based on preheating time.

    As described above, according to the present invention, when the deterioration state of the catalyst is detected during engine operation, the target temperature of the catalyst is set according to the deterioration state of the catalyst, and the engine start is predicted. In addition, since the catalyst is preheated so as to reach the target temperature, it is possible to ensure immediate purification performance even when the engine is started at a low temperature regardless of the deterioration of the catalyst.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings.

    In FIG. 1, reference numeral 1 denotes an engine of a vehicle, 2 denotes an exhaust passage thereof, and an electrically heated exhaust gas purification catalyst 3 is provided in the exhaust passage 2. The catalyst 3 is directly connected to the exhaust manifold of the engine 1, and an exhaust gas purifying catalyst (three-way catalyst) without a heater is provided under the floor of the vehicle. The catalyst 3 alone may cover the exhaust gas purification of the vehicle, and the catalyst 3 is not necessarily connected directly to the exhaust manifold.

    The catalyst 3 of this embodiment is a catalyst in which a three-way catalyst is supported on a metal carrier. By energizing from the battery 6 between the center electrode 4 arranged at the center of the metal carrier and the outer electrode 5 arranged at the outer periphery of the metal carrier, the catalyst 3 is preheated before starting the engine (heating temperature is increased). ) Therefore, in the case of this embodiment, the metal carrier and the electrodes 4, 5 constitute a catalyst heater (heating means) that heats the catalyst 3 by energization from the battery 6. The battery 6 is used for starting the engine 1.

    A thermocouple 7 is attached to the catalyst 3 as catalyst temperature detecting means. An upstream oxygen sensor 8 that detects the oxygen concentration of the exhaust gas flowing into the catalyst 3 is provided upstream of the catalyst 3 in the exhaust passage 2, and downstream of the catalyst 3 in the exhaust passage 2. A downstream oxygen sensor 9 for detecting the oxygen concentration of the exhaust gas flowing out from the catalyst 3 is provided. The oxygen sensors 8 and 9 can detect the amount of oxygen per unit time used for purifying exhaust gas by the catalyst 3 during engine operation. The smaller the amount of oxygen, the more the catalyst 3 deteriorates. Can be determined. Accordingly, both oxygen sensors 8 and 9 constitute a catalyst deterioration state detecting means.

    In addition, at least one of the oxygen sensors 8 and 9 is used for air-fuel ratio control of the engine 1, and by controlling the oxygen concentration of exhaust gas flowing into the catalyst 3 by the air-fuel ratio control, Exhaust gas purification performance can be exhibited efficiently. In the present embodiment, the upstream oxygen sensor 8 is mainly used for air-fuel ratio control, and the upstream oxygen sensor 8 is used as a sensor with an electric heater so that the air-fuel ratio control can be accurately performed immediately after the engine is started. Before starting the engine, the sensor 8 is preheated using the battery 6 so as to reach an optimum temperature for oxygen concentration detection.

    Reference numeral 11 in FIG. 1 denotes control means using a microcomputer for preheating the catalyst 3 and the oxygen sensor 8. The control means 11 includes a behavior pattern learning / storage unit for a driver who drives the vehicle, a timer, and a control unit (preheating control unit) for controlling various conditions and preheating the catalyst 3 and the oxygen sensor 8. Yes. For this preheating control, the control means 11 is supplied with detection signals from the above-mentioned thermocouple 7 and oxygen sensors 8 and 9, as well as a remaining capacity signal from the battery 6, an engine water temperature signal, and the approach of the passenger to the vehicle. Signals, signals relating to vehicle conditions (opening / closing of driver's seat doors, presence / absence of passenger seating, etc.), engine start signals, and the like are given. Then, the preheating control unit gives a control signal to the energization control unit 12 that controls the energization amount from the battery 6 to the catalyst heater. In addition, illustration of the electricity supply circuit from the battery 6 to the oxygen sensor 8 with a heater is abbreviate | omitted.

    FIG. 2 is an explanatory diagram of a means (engine start prediction means) for detecting whether or not the occupant 15 has approached the vehicle 16 up to a predetermined distance. In the figure, reference numeral 17 is a remote unit carried by the occupant 15, and 18 is an in-vehicle unit provided in the vehicle 16. The remote unit 17 is provided with a first coil antenna, a transmitter, and a control circuit, and the in-vehicle unit 18 is provided with a second coil antenna, a receiver, and a control circuit.

    That is, the activation electromagnetic wave is transmitted from the second coil antenna by the control circuit of the in-vehicle unit 18. When both units 17 and 18 approach within a predetermined distance, in other words, when the occupant 15 approaches the vehicle 16 to a predetermined distance, electromagnetic induction coupling occurs between the first and second coil antennas. Accordingly, the remote unit 17 transmits a signal indicating the approach of the occupant 15 from the transmitter to the in-vehicle unit 18 based on the current from the first coil antenna. When the predetermined signal is received by the receiver, the in-vehicle unit 18 outputs a control signal for unlocking the door and the like, and gives an occupant approach signal to the control means 11 described above.

    Further, the in-vehicle unit 18 includes an approach distance setting means for arbitrarily setting the predetermined distance, that is, a distance in which the first coil antenna and the second coil antenna can be electromagnetically guided, and a second distance corresponding to the distance setting. An output variable circuit for changing the transmission output of the electromagnetic wave for activation by the coil antenna is provided. As a result, the occupant can set the predetermined distance to an appropriate distance for himself / herself, which unlocks the door when approaching the vehicle 16 and starts preheating described later.

    The vehicle 16 is provided with a door switch (not shown) for detecting the opening / closing of the door 19 next to the driver's seat, and a door opening / closing signal from the door switch is given to the control means 11.

    As shown in FIG. 3, the driver seat 21 is provided with a load sensor 22 that detects the seating of an occupant. That is, the base member 25 is attached to the floor panel 23 via the seat bracket 24, the load sensor 22 is disposed between the base member 25 and the seat slide rail 26, and the driver seat 21 is moved forward and backward on the seat slide rail 26. It is supported movably. A detection signal from the load sensor 22 is given to the control means 11. The control means 11 determines that an adult, that is, a driver, is seated on the driver seat 21 when a load of a predetermined value (for example, 40 kg) or more is detected by the load sensor 22.

    Next, the behavior pattern learning / storage unit will be described. This is based on the driving history of the vehicle 16 by the occupant, and learns and stores the behavior pattern related to the vehicle driving start of the occupant in association with time. In particular, the time (time) for the occupant to approach the vehicle 16 for driving, the longest scheduled time t1 required for opening the door 19 from the approach, the longest time required for sitting on the driver's seat 21 from the door opening. The scheduled time t2 and the longest scheduled time t3 required for starting the engine 1 from the seating are learned and stored. In addition, such behavior patterns generally differ depending on the day of the week, such as, for example, different between weekdays and holidays, or vary depending on the month or season, so they are learned and stored in association with the calendar.

    Specifically, each time the engine 1 is started by the occupant, the occupant approach signal, the door open signal, the occupant seating signal, and the engine start signal are input to the control means 11 each time the engine 1 is started by the occupant. Time is read. As for passenger approach time, when a predetermined number of approach time data for the same calendar condition is obtained (for example, when Monday to Friday is a weekday, five approach time data for that weekday are obtained) ), The data is averaged, and an error (variation) of about 10 minutes before and after, for example, is added to the averaged approach time and stored as an occupant approach time (for example, 7:30 am to 7:50 am) To do.

    As for scheduled times t1, t2, and t3, when a predetermined number of required time data is obtained for each of the calendar conditions that are the same on the same day when the passenger approaches, the door opens, the passenger opens from the door, and the engine starts from the passenger sitting, The data is averaged, and, for example, about 30 seconds is added to the average required time as an extra time, and stored as each longest scheduled time.

    In addition, the occupant approach time and the longest scheduled times t1, t2, and t3 of the door opening, occupant seating, and engine start are averaged each time the predetermined number of data is obtained, and the deviation from the previous value is obtained. The memory is updated by reflecting the amount in the previous value by a predetermined ratio.

    The preheating control unit of the control means 11 sets a preheating target temperature according to the deterioration state of the catalyst 3, determines whether or not to preheat based on information on passenger approach and remaining battery capacity, delays in starting preheating based on the initial catalyst temperature, door Control such as opening, occupant seating, change of preheating temperature increase gradient based on presence / absence of engine start or stop of preheating is performed. Hereinafter, a specific description will be given with reference to the control flow shown in FIG. 4 and the time chart shown in FIG.

    In FIG. 4, various signals such as an occupant approach signal are read in step S <b> 1 after the start, and it is determined in subsequent step S <b> 2 whether the engine is operating. If the engine is operating, the deterioration state of the catalyst is detected based on the detection signals of the oxygen sensors 8 and 9 in the subsequent step S3, and the preheating target temperature corresponding to the deterioration state of the catalyst 3 is set in the subsequent step S4. In the present embodiment, basically, the light-off temperature of the catalyst 3 (the catalyst temperature at which the exhaust gas purification rate becomes 50%) is set as the target temperature. That is, when no detectable deterioration has occurred in the catalyst 3, the fresh light-off temperature of the catalyst 3 is set as the target temperature, and the target temperature is set higher as the degree of deterioration increases. However, even when the catalyst 3 is deteriorated, the maximum value of the target temperature is the light-off temperature at fresh time + 50 ° C. (see FIG. 5).

    When it is determined in step S2 that the engine is not operating, the process proceeds to step S5, where it is determined whether the occupant carrying the remote unit 17 has approached the vehicle 16, that is, whether an occupant approach signal has been issued from the in-vehicle unit 18. The When the occupant approach signal is output, it is determined in subsequent step S6 whether or not the time when the approach signal is output is within the occupant approach time stored in the occupant behavior pattern learning / storage unit. When the occupant approach signal is output within the occupant approach time, in the subsequent step S7, it is determined whether or not the current battery remaining capacity is equal to or less than a predetermined value, that is, the remaining capacity of the battery 6 when the catalyst 3 is preheated. It is determined whether or not the engine can be started.

    When the engine 1 can be started even after the catalyst preheating, the process proceeds to step S8, and it is determined whether or not the initial temperature (temperature before starting preheating) T of the catalyst 3 is equal to or higher than a predetermined temperature To. The predetermined temperature To is changed according to the preheating target temperature, and for example, a catalyst temperature that is desired to be reached when the door 19 next to the driver's seat is opened is employed. In this case, as shown in FIG. 5, the predetermined temperature To when the catalyst 3 has a detectable deterioration and the predetermined temperature To ′ when the catalyst 3 has deteriorated are different from the former in the latter. Is also set higher. Of course, a specific temperature higher than the normal temperature may be set as the predetermined temperature To regardless of the preheating target temperature of the catalyst 3 or the degree of deterioration. When the catalyst initial temperature T is lower than the predetermined temperature To (or To ′), the process proceeds to step S9 and preheating of the catalyst 3 and the oxygen sensor 8 is started. The temperature rising gradient of the catalyst 3 at this time is set to be low.

    In subsequent step S10, it is determined whether or not the door 19 is opened. When the door 19 is not open, the routine proceeds to step S11, where it is determined whether or not a scheduled time t1 from the occupant approach (the time when the occupant approach signal is issued; hereinafter the same) to the door open has elapsed. If the door 19 cannot be opened even after the scheduled time t1 has elapsed, the process proceeds to step S12, and the preheating of the catalyst 3 and the oxygen sensor 8 is stopped. On the other hand, when the door 19 is opened before the scheduled time t1 elapses, the routine proceeds to step S13, where the amount of power supplied from the battery 6 to the catalyst heater is increased, and the temperature increase gradient of the catalyst 3 is increased (see FIG. 5). ).

    In a succeeding step S14, it is determined whether or not the occupant is seated on the driver's seat 21. When not seated yet, the routine proceeds to step S15, where it is determined whether or not the scheduled time t2 from the door opening to the passenger seating has elapsed. If the occupant is not seated even after the scheduled time t2, the pre-heating of the catalyst 3 and the oxygen sensor 8 is stopped in step S12. On the other hand, when the occupant is seated before the scheduled time t2 elapses, the routine proceeds to step S16, where it is determined whether or not the seated occupant is an adult, that is, a driver. When the person is not an adult, the process proceeds to step S12, and the preheating of the catalyst 3 and the oxygen sensor 8 is stopped. When the person is an adult, the process proceeds to step S17, and the energization amount from the battery 6 to the catalyst heater is further increased. The temperature rising gradient is further increased (see FIG. 5).

    In a succeeding step S18, it is determined whether or not the engine 1 has been started. When the engine 1 has not been started yet, the routine proceeds to step S19, where it is determined whether or not the scheduled time t3 from the passenger seating to the engine starting has elapsed. If the engine is not started even after the scheduled time t3 has elapsed, the routine proceeds to step S12, and the preheating of the catalyst 3 and the oxygen sensor 8 is stopped. On the other hand, when the engine 1 is started before the scheduled time t3 elapses, the routine proceeds to step S20, where it is determined whether the catalyst 3 has reached the target temperature based on the detection signal from the thermocouple 6, When the target temperature is reached, the routine proceeds to step S21 where the preheating of the catalyst 3 and the oxygen sensor 8 is terminated.

Further, in step S8, the catalyst initial temperature T When it is determined to be equal to or greater than the predetermined temperature To process proceeds to step S22, the preheating start time delay t _d in accordance with the catalyst initial temperature T is set. The delay time t _d is set to be longer as the catalyst the initial temperature T rises.

In the subsequent step S23 the delay time t _d is whether less than the expected time t4 from the occupant proximity to the occupant seated (= t1 + t2) is determined. When t _d <t 4, preheating of the catalyst 3 and the oxygen sensor 8 is started after the elapse of the delay time t _d (steps S24 and S25). Is determined. When the delay time t _d is equal to or longer than the scheduled time t 4, preheating of the catalyst 3 and the oxygen sensor 8 is started after the delay time t _d has elapsed (steps S26 and S27), and then the process proceeds to step S18, where the engine 1 It is determined whether or not is started.

    Therefore, when the occupant approaches the vehicle 16 within the occupant approach time stored in the occupant behavior pattern learning / storage unit, if the remaining battery capacity is equal to or greater than a predetermined value, in principle, the catalyst 3 and the oxygen sensor 8 are preheated. Be started. Therefore, preheating of the catalyst 3 can be started early, the temperature of the catalyst 3 can be surely raised to the target temperature before the engine is started, and the desired exhaust gas purification rate can be obtained from the time of starting the engine. In addition, the oxygen sensor 8 can be set to an optimum temperature for sensing in advance, which is advantageous in efficiently operating the catalyst 3 by air-fuel ratio control. On the other hand, when the occupant simply approaches the vehicle 16, the preheating of the catalyst 3 is not started, and only when it is determined from the normal behavior pattern of the occupant that the driving of the vehicle is likely to be started. Since the preheating of the catalyst is started, it is avoided that the catalyst is preheated unnecessarily.

    Further, since the target temperature is set according to the deterioration state of the catalyst 3, it is advantageous in obtaining the desired exhaust gas purification rate from the time of starting the engine regardless of the deterioration of the catalyst 3. Further, when the remaining battery capacity is small, preheating of the catalyst 3 is prohibited, so that the engine start is not hindered.

    In addition, even when preheating is started, when the door 19 cannot be opened by the scheduled time, when the passenger does not sit on the driver's seat 21 by the scheduled time, or when the engine is not started by the scheduled time, the preheating is performed. Since it is canceled, it is advantageous in reducing energy loss. In particular, as shown in FIG. 5, since the temperature rising gradient for catalyst preheating is increased in stages as the door is opened and the passenger is seated, the energy loss when preheating is stopped halfway is reduced. Can be minimized.

    Further, when the desired catalyst temperature T is equal to or higher than the predetermined temperature To, the start of preheating is delayed, so that the preheating of the catalyst 3 is completed too early and the preheating state is wasted until the engine is started. Can be avoided and energy loss can be suppressed.

    When starting the engine 1 after the occupant wears the seat belt, the occupant behavior pattern learning / memory means similarly learns / stores the longest scheduled time from the occupant seating to the seat belt wearing. When the seat belt is not worn inside, preheating of the catalyst or the like may be stopped.

    Also, the scheduled time from occupant approach to door opening, the scheduled time from occupant approach to occupant seating, the scheduled time from occupant approach to seat belt use, and the scheduled time from occupant approach to engine start are stored in the action pattern storage means. The preheating of the catalyst or the like may be stopped when the action is not taken after each scheduled time.

    In the above embodiment, preheating of the oxygen sensor 8 is started simultaneously with preheating of the catalyst 3. However, preheating of the oxygen sensor 8 may be started before starting preheating of the catalyst 3 or the heat capacity of the oxygen sensor 8. Since it is smaller than the catalyst 3, preheating of the oxygen sensor 8 may be started after starting the preheating of the catalyst 3 and before starting the engine.

1 is a configuration diagram of an exhaust gas purifying catalyst preheating system according to the present invention. FIG. It is explanatory drawing of the passenger | crew approach detection means of the same system. It is a side view which shows the driver's seat provided with the passenger seating detection means of the system in a partial cross section. It is a control flow figure of the system. It is a time chart figure of the system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Exhaust passage 3 Exhaust gas purification catalyst 6 Battery 7 Thermocouple (catalyst temperature detection means)
8,9 Oxygen sensor (catalyst deterioration detection means)
11 Control means

Claims (7)

A method for preheating an exhaust gas purifying catalyst provided in an exhaust passage of an engine,
Detecting a deterioration state of the catalyst;
Setting a target temperature of the catalyst according to the deterioration state of the catalyst;
Predicting the start of the engine;
A catalyst preheating method for purifying exhaust gas, comprising the step of starting preheating of the catalyst so that the catalyst reaches the target temperature when the start of the engine is predicted. In claim 1,
An oxygen sensor for detecting the oxygen concentration of the exhaust gas is provided upstream or downstream of the catalyst in the exhaust passage,
Exhaust gas comprising a step of starting preheating of the oxygen sensor before the start of preheating of the catalyst, simultaneously with the start of preheating, or after the start of preheating when the start of the engine is predicted. Catalyst preheating method for gas purification. In claim 1 or claim 2,
The engine is a vehicle driving engine,
A catalyst preheating method for exhaust gas purification, wherein when the occupant driving the vehicle approaches the vehicle up to a predetermined distance, the start of the engine is predicted and the catalyst is preheated. In claim 3,
The catalyst preheating method for exhaust gas purification, wherein the catalyst preheating is stopped when the time from when the occupant approaches the vehicle to a predetermined distance until the door of the vehicle opens is a predetermined time or more. . In any one of Claims 1 thru | or 4,
A catalyst preheating method for exhaust gas purification, comprising delaying the start of preheating of the catalyst when the temperature of the catalyst is equal to or higher than a predetermined temperature at the time when the start of the engine is predicted. In any one of Claims 1 thru | or 5,
A battery for supplying electric power for starting the engine;
A catalyst preheating method for purifying exhaust gas, wherein when the remaining capacity of the battery is equal to or less than a predetermined value when the start of the engine is predicted, preheating of the catalyst with the power of the battery is prohibited. Catalyst heating means for heating the exhaust gas purifying catalyst of the engine;
Catalyst temperature detecting means for detecting the temperature of the catalyst by measuring or estimating the temperature of the catalyst;
Catalyst deterioration state detecting means for detecting the deterioration state of the catalyst;
Means for setting a target temperature of the catalyst according to the deterioration state of the catalyst detected by the catalyst deterioration state detection means;
Means for predicting the start of the engine;
When the start of the engine is predicted, the catalyst heating means is operated to start raising the temperature of the catalyst so that the catalyst is brought to the target temperature based on the temperature detected by the catalyst temperature detecting means. And a catalyst preheating control means for raising the temperature of the exhaust gas purification catalyst.

Images