JP2706928B2 - Preheat control device for catalyst with heater - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a preheat control device for a catalyst with a heater capable of promoting activation of the catalyst when the engine is started in a refrigerant state.

(Prior Art) In an exhaust system of a vehicle, an exhaust gas purifying device that makes exhaust gas generated by the vehicle harmless and discharges the exhaust gas to the atmosphere is mounted, thereby preventing deterioration of a natural environment.

The catalyst used in this exhaust gas purification device, for example, a three-way catalyst has both oxidation and reduction catalysts, and by maintaining the air-fuel ratio in a narrow window region including stoichiometry, the oxidation catalyst reduces CO and HC in the exhaust gas. catalyst is acting to convert NO _X in the exhaust gas into harmless components, respectively.

However, this three-way catalyst does not show a catalytic action until the predetermined activation temperature is reached. In some cases, the catalyst is warmed up at the time of a cold start of the engine before starting the warm-up operation of the engine.

At that time, the catalyst is heated with a heater in order to promote the warm-up and activate the catalyst early. By this heater heating, the inactive operation time of the catalyst at the time of cold start of the engine is reduced, and the amount of exhaust gas generated at the time of cold start is reduced.

(Problems to be Solved by the Invention) However, such a conventional heater heating process for early activation is started after the driver has turned on the key, and the waiting time after the key-on is painful for the driver. It may be.

An object of the present invention is to provide a preheat control device for a catalyst with a heater, which can reduce a waiting time for a heater heating process performed in early activation of the catalyst.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a power supply circuit connected to a heater for heating an exhaust gas purifying catalyst, and a predetermined duty ratio between the heater and the power supply circuit. A switch for opening and closing, an opening and closing control means for outputting a predetermined duty ratio signal to the switch, and a driving start prediction signal generating means for generating a driving start prediction signal by detecting that the driver enters a boarding operation. Wherein the switching control means outputs a predetermined duty ratio signal to the switch in response to the operation start prediction signal.

(Operation) The switching control means, which has received the operation start prediction signal from the operation start prediction signal generation means, outputs a predetermined duty ratio signal to the switch, and the switch is supplied to the heater at a predetermined duty ratio. Power can be increased or decreased.

(Embodiment) The preheat control device for a catalyst with a heater shown in FIG. 1 is attached to an exhaust gas purifying device A mounted on an exhaust passage 2 of a gasoline engine 1.

Here, the engine 1 is configured so that the fuel supply amount is controlled by an engine control unit (hereinafter simply referred to as a controller) 3.

An air cleaner 5 is attached to an intake passage 4 connected to the main body of the engine 1, and a catalytic converter 7 and a muffler 18 are attached to an exhaust passage 2 in the middle of an exhaust pipe 6.

A three-way catalyst 8 is disposed inside a casing 10 of the catalytic converter 7, and in particular, the three-way catalyst 8 is provided with a heater 9 for heating the three-way catalyst. A power supply circuit 12 having a battery 13 is connected to the heater 9 via a switch 11.

The three-way catalyst 8 has a catalytically active component that can be redox-treated in a stoichiometric atmosphere on the entire inner wall surface of the monolithic carrier. The three-way catalyst 8 is an exhaust gas air-fuel ratio is in the neighborhood stoichiometric, when in the active temperature performs HC, CO, NO _X, the redox treatment of, taking a known structure that can discharge the detoxified exhaust gas.

A secondary air pipe 14 communicates with the exhaust pipe 6 at a position upstream of the catalytic converter 7, and the pipe 14 is connected to the air cleaner 5 via an air compressor 15. The compressor 15 is driven to rotate by the engine 1, and a built-in electromagnetic clutch is connected to the secondary air controller 16.

When receiving the drive command signal from the controller 3, the secondary air controller 16 can connect the electromagnetic clutch, drive the compressor 15, and supply the secondary air to the exhaust path 6.

Reference numeral 17 in FIG. 1 indicates a catalyst temperature sensor that outputs internal temperature information of the three-way catalyst 8. Furthermore, reference numerals 19, 20, 2
Reference numerals 1 and 22 denote a door knob switch, a water temperature sensor, an intake air temperature sensor, and a cranking switch, respectively, in this order.

Here, the door knob switch 19 forms a driving start prediction signal generating means for detecting that the driver enters the riding behavior and generating a driving start prediction signal (hereinafter, referred to as a preheat-on signal S). The switch 19 is provided opposite to a door knob of a driver's seat (not shown) of the vehicle, and is configured to emit a preheat-on signal S when the door knob is opened. The water temperature sensor 20 can output the temperature information of the cooling water of the engine 1, the intake air temperature sensor 21 can output the air temperature information in the air cleaner 5, and the cranking switch 22 is constituted by a crank angle signal generator in a distributor (not shown). ing.

The above-described switch 11, as shown in FIG. 3, is formed by a CMOS in which a P-channel MOS Q1 and an N-channel MOS Q2 are combined. A drive output P having a predetermined duty ratio is input from the controller 3 to the input terminal T1, and an output terminal
The heater 9 is connected to T2. The source of the P-channel MOS Q1 is connected to the ground, and the source of the N-channel MOS Q2 is connected to the 12V terminal of the battery 13.

Thereby, when the pulse signal Sp as the duty ratio signal is input from the controller 3 to the input terminal T1,
A drive output Du having a duty ratio for switching the potential from 0 V to 12 V as shown in FIG. 2 (a waveform having a duty ratio of about 60% is shown in FIG. 2) is supplied to the heater 9.

Such a CMOS switch 11 has a relatively small power consumption (amount of pigeon heat) and effectively functions as the switch 11 of the power supply circuit 12 which requires a relatively large heater power for early activation.

The main part of the controller 3 is constituted by a microcomputer. In particular, the controller 3 receives the output information of each of the above-mentioned sensors and takes in the information in a timely manner, or a pulse signal Sp.
And an input / output circuit 301 for outputting a drive command signal to the secondary air controller 16, a preheat control program shown in FIG. 5, and FIGS. 4 (a), (b), (c), (d), (e). )
And a control circuit 303 for calculating a control value in accordance with a control program, and the like.

Here, the catalyst temperature correction value K1 calculation map shown in FIG. 4 (a) sets K1 to 1 when the catalyst temperature is 350 ° or lower, and gradually reduces the value from 1 to 0 in a change range α up to 450 °. , 450 ° or more, activation is completed and the heater 9 is set to be turned off.

The on-time correction value K2 calculation map shown in FIG. 4 (b) sets the correction value K2 to 1 until the time since the heater is turned on for 30 seconds, and gradually changes the value of K2 from 1 in the change range α up to 60 seconds. The setting is made to decrease to 0, and to turn off the heater 9 after 60 seconds to protect the battery.

In the battery voltage correction value K3 calculation map of FIG. 4C, the correction value K3 is set to 1 when the battery voltage V is 12 V or more, and in a change range α between 12 and 10 V, according to the voltage drop,
It is set to gradually decrease the value from 1 to 0, and to cut off the heater 9 at 10 V or less to protect the battery.

The water temperature correction value K4 calculation map shown in FIG.
In the above, the correction value K4 is set to 1, and the value is gradually reduced from 1 to 0 in accordance with the temperature drop in the change range α between 0 ° C. and −10 ° C. Heater 9
Is set to cut.

In the intake air temperature correction value K5 calculation map shown in FIG. 4E, the correction value K5 is set to 1 when the intake air temperature is 0 ° C. or higher, and in a change range α between 0 ° C. and -10 ° C. The value is gradually reduced from 1 to 0, and the heater 9 is set to be turned off at -10 ° C or lower to protect the battery.

The controller 3 has at least a function as a preheat control unit.

The controller 3 executes a well-known main routine for engine operation control processing from an engine key-on (not shown) and other interrupt processing.
Stop the main routine and others. Then, during the key-off, the preheat control process is executed when the preheat-on signal S is input.

When entering the preheat control routine, first, a timer is started, each piece of detection information is fetched from each sensor, and stored in a predetermined area.

When the timer reaches step a3, the process proceeds to step a4 while the timer does not elapse a predetermined elapsed time (here, set to 5 seconds). Here, based on each data, the catalyst temperature correction value K1,
On-time correction value K2, battery voltage correction value K3, water temperature correction value
K4 and the intake air temperature correction value K5 are stored in a predetermined map (FIG. 4 (a),
(Refer to the duty ratio correction value maps of (b), (c), (d), and (e)). Then, based on the following equation, the duty ratio Du is calculated and stored in the address Du.

Du = K1 × K2 × K3 × K4 × K5 Here, the current value I according to the duty ratio Du and the battery voltage V is further calculated based on a predetermined map, and stored in the address I.

When the current value I reaches step a5, it is determined whether or not the current value I is zero. When the current value I is not zero, the process proceeds to step a6, a flag H is set, and it is determined whether or not the current cranking is performed. If it is not cranking, the process proceeds to step a8, where a pulse signal Sp having the duty ratio of the address Du is output to the switch 11, which generates a drive output P, and returns to step a2.

As a result, the heater 9 has a predetermined duty ratio Du.
Is supplied with electric power whose current value is regulated.

For example, if the catalyst temperature is 350 ° C or less,
Before 0 seconds, battery voltage is over 12V, water temperature is 0 ℃
As described above, when the intake air temperature is 0 ° C. or higher, the catalyst temperature correction value K1,
On-time correction value K2, battery voltage correction value K3, water temperature correction value
K4 and intake air temperature correction value K5 are all 1 and the duty ratio is Du =
1 and the switch is 100% open and 100
% Of electric power is supplied, and early activation of the catalyst is most efficiently achieved. In particular, the driving of the heater 9 is started before the driver completes the boarding, and the waiting time during the preheating is significantly reduced, so that the driver does not feel the pain caused by the prolonged waiting time.

On the other hand, if the calculation range of the correction value is in the change range α,
Each correction value decreases, and the duty ratio Du becomes 100%
More between 0%. In this case, the amount of power supplied from the power supply circuit 12 is reduced, and this process protects the battery, prolongs the driving time of the heater 9 as much as possible, and promotes the activation of the catalyst.

On the other hand, if one of the correction values has become zero in step a4, the duty ratio Du becomes zero. In this case, the process proceeds to step a10 in step a5, where the flag H is cleared, and the process reaches step a8. In addition, the power supply from the power supply circuit 12 is cut off.
Only battery protection is achieved. In such a case, a preheat process for catalyst activation in the main routine is performed.

On the other hand, if cranking has been performed in step a7, the process proceeds to step a9, the current duty ratio Du is set to zero, and the process proceeds to step a8, in which the power supply from the power supply circuit 12 is cut off. In such a case, the battery 13
Since the cranking cannot be properly performed if the voltage drop occurs, the heater is turned off to give priority to the cranking.

The control sequence is repeated again to reach step a3. At this time, if 5 seconds have already elapsed from the start, the process proceeds to step a11. Here, the current value I is not zero and the flag H
If the flag H is 1, the process proceeds to step a4, but if the flag H is zero, the preheat control is ended or the process returns to the main routine.

The controller 3 is configured to output a drive output to the secondary air controller 16 when the catalyst temperature from the catalyst temperature sensor 17 reaches a predetermined value. Thereby, when the secondary air controller 16 receives the drive command signal from the controller 3, the secondary air controller 16 engages the electromagnetic clutch, and
To supply secondary air to the exhaust path 6 to perform exhaust gas purification processing.

In the above-described process, the power supply circuit 12 is shown to be used for driving auxiliary equipment of the engine and each electric device of the vehicle in addition to the heater heating. It may be configured as shown in the figure.

In this case, the power supply circuit 12 'has a dedicated battery 23 dedicated to driving the heater 9 and a battery 24 for driving auxiliary equipment of the engine and each electric device of the vehicle.

The dedicated battery 23 is directly connected to the switch 11, and the battery 24 is connected via a normally open battery switch 25 that is closed by the controller 3. When the voltage drop of the dedicated battery 23 advances by a predetermined amount, the controller 3 closes the battery switch 25 so that the dedicated battery 23 and the battery 24 can be connected in parallel.

In this case, it is easy to prevent the battery from being weakened, and it is not necessary to stop the operation of the heater 11 during the cranking drive.

It is desirable to provide a second electric energy source in the power supply circuit 12 in addition to the batteries 13 and 23. As the second electric energy source, the above-described battery 24 may be provided. In addition, a solar cell, a power generation system that converts braking energy into electric energy, or the like may be added.

In the above process, the doorknob switch 19 has been described as the operation start prediction signal generating means.
A switch may be attached to the door key cylinder of the driver's seat door, and the switch may output a preheat-on signal S by inserting a key.Furthermore, a keyless entry system is mounted on the driver's door, The unlock signal can be obtained from the remote use card.

(Effect of the Invention) As described above, according to the present invention, upon receiving the operation start prediction signal (preheat on signal S) from the operation start prediction signal generation means, the opening / closing control means drives the switch at a predetermined duty ratio, Since the switch adjusts the power supplied to the heater at a predetermined duty ratio, the waiting time for the heater heating of the catalyst can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a preheating control device for a catalyst with a heater as one embodiment of the present invention, FIG. 2 is a waveform diagram of a drive output P output from a switch of the same device, and FIG. Circuit diagrams of switches, FIGS. 4 (a), (b), (c),
(D) and (e) are characteristic diagrams of duty ratio correction value maps incorporated in the controller of the above-mentioned device, FIG. 5 is a flowchart of a preheat control program executed by the controller of the above-mentioned device, and FIG. It is a whole block diagram of the catalyst preheating control apparatus with a heater as another Example. 1 ... engine, 2 ... exhaust path, 3 ... controller,
8 ... three-way catalyst, 9 ... heater, 11 ... switch, 12 ...
Power circuit, 13 ... battery. 4

Claims (1)

(57) [Claims] 1. A power supply circuit connected to a heater for heating a catalyst for purifying exhaust gas, a switch for opening and closing the heater and the power supply circuit at a predetermined duty ratio, and a predetermined duty ratio signal to the switch. Opening / closing control means for outputting, and driving start prediction signal generating means for generating a driving start prediction signal by detecting that the driver enters the boarding action, wherein the opening / closing control means responds to the driving start prediction signal. A preheat control device for a catalyst with a heater, which outputs a predetermined duty ratio signal to the switch.