JP2006352974A - Controller for generator for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the drop of the rotational speed of an engine and the instabilization at operation of a secondary air supply means such as a secondary air pump or the like. <P>SOLUTION: An alternator 1 generates power, being driven by an engine 2, and supplies an electric load 4 and a battery 5 with generated power. The secondary air pump 16 supplies an exhaust passage 13 with secondary air thereby ativating the catalyst 14 in its early stage by operating when the catalyst 14 is cold. A C/U 10 controls the quantity of generated power of the alternator 1, according to the oepration state of the engine, etc. on one hand, and stops the power generation of the alternator 1 or suppresses the quantity of generated power at operation of the secondary pump 16 on the other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a vehicular generator driven by an engine, and more particularly to power generation (amount) control of a vehicular generator during operation of a secondary air pump.

In Patent Document 1, in order to prevent a decrease in engine speed and instability due to a power generation load that increases when an electric load such as an air conditioner or a light is turned on during idle operation, an air amount is controlled by an idle speed control valve. It is described that the correction is increased.
Patent Document 2 describes that the catalyst is activated early by sending secondary air (fresh air) to the upstream side of the catalyst in the exhaust passage immediately after the engine is started.
JP-A-8-284712 JP-A-1-227814

By the way, an electric load such as an air conditioner or a light as described in the former is usually turned on after the start is completed, and the load level at the time of turning on is relatively small. Is relatively easy to handle.
However, the secondary air pump for feeding the secondary air has a large inrush current (electric load at the time of charging) due to the motor load, and the charging timing is also when the engine friction from cranking to complete explosion is large. Therefore, it becomes a big load with respect to an engine. For this reason, a decrease in engine speed or instability is caused, and in the worst case, engine stall may occur.

In response to such a decrease in the engine rotation speed during the operation of the secondary air pump in the air system as in the conventional technique, it is difficult to effectively prevent this due to a response delay. In addition, in response to the fuel system, it is difficult to apply an appropriate correction to the transient state at the time of starting, and there is a risk that exhaust will be deteriorated.
The present invention has been made paying attention to such a conventional problem, and an object of the present invention is to provide a secondary air supply means for an engine having a secondary air supply means for supplying secondary air to an exhaust system. The object is to effectively prevent a decrease in engine rotation speed during operation.

Therefore, the present invention provides a control device for a vehicular generator driven by an engine, wherein the vehicular generator is operated during operation of secondary air supply means for supplying secondary air to the exhaust system of the engine. The power generation is stopped or the power generation amount is suppressed.
In this way, even if the electrical load increases due to the operation of the secondary air supply means, the increase in the load on the engine can be reduced, so that a decrease in engine speed and instability can be prevented.

  Further, it is desirable to stop the power generation of the vehicle generator or suppress the power generation amount for a predetermined period from the start of the engine. The secondary air supply means often operates immediately after the start because of early activation of the catalyst. Immediately after the start, the engine friction itself is large, and the secondary air supply means operates to further increase the load on the engine. This is because the engine rotation speed is likely to decrease or become unstable.

Furthermore, the power generation stop of the vehicle generator or the suppression of the power generation amount may be performed when the electric load of the vehicle is a predetermined amount or more. This is because power generation is stopped or the amount of power generation is suppressed only when there is a high possibility that the engine rotational speed will decrease or become unstable.
In addition, when the power generation stop of the vehicle generator or the suppression of the power generation amount is released, it is desirable to shift to the normal power generation control after performing the control (gradual excitation control) for gradually increasing the power generation amount. This is for smoothly switching the control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of a system configuration according to an embodiment of the present invention. As shown in this figure, a vehicular generator (hereinafter referred to as “alternator”) 1 is mechanically connected to an engine 2. A belt 3 is wound between a pulley 1a and a crank pulley 2a of the alternator 1, and the alternator 1 is driven to rotate by the engine 2.

The driven alternator 1 generates power to supply electric power to the electric load 4 of the vehicle and charges the battery 5. Note that the electric load 4 of the vehicle corresponds to an air conditioner, a headlight, a power steering, or the like.
Further, the alternator 1 includes an IC regulator 6. The IC regulator 6 adjusts the power generation amount of the alternator 1 by operating based on a drive signal from a control unit (C / U) 10 described later.

  Air is sucked into the engine 2 through an intake passage 9 in which an air cleaner 7 that removes dust and the like in the air, a throttle valve 8 that adjusts the amount of air passing therethrough, and the like are interposed. A bypass passage 10 that bypasses the throttle valve 8 is connected to the intake passage 9. An ISC valve 11 that adjusts the amount of air passing through the bypass passage 10 (bypass air amount) is connected to the bypass passage 10. It is intervened.

Each cylinder of the engine 2 is provided with a fuel injection valve and an ignition plug (both not shown), and injects fuel based on a drive signal from the C / U 10 to ignite a mixture of fuel and air. To do.
Combustion exhaust from the engine 2 is exhausted through the exhaust passage 13. An exhaust purification catalyst (hereinafter referred to as “catalyst”) 14 is interposed in the exhaust passage 13. Further, a secondary air supply passage 15 that connects the downstream side of the air cleaner 7 in the intake passage 9 and the upstream side of the catalyst 14 in the exhaust passage 13 is provided. The secondary air supply passage 15 is provided with the air cleaner 7. A secondary air pump 16 that sucks and pressurizes air from which dust or the like has been removed, a pressure regulator 17 that regulates the air discharged from the secondary air pump 16 to a predetermined pressure, and a supply of secondary air from the pressure regulator 17 A secondary air control valve 18 for adjusting the amount is interposed. In the present embodiment, the secondary air pump 16 corresponds to the secondary air supply means according to the present invention, but this is only an example, and the secondary air is operated at a predetermined timing to supply the secondary air to the exhaust system. Any device or configuration may be used.

The operation (ON / OFF) of the secondary air pump 16 is controlled by the C / U 10. The secondary air pump 16 is also supplied with electric power from the alternator 1 (or the battery 5), and is one of the electric loads of the vehicle. The opening degree (opening / closing operation) of the secondary air control valve 18 is also controlled by the C / U 10.
The C / U 10 includes an engine coolant temperature TW from the water temperature sensor 21, an engine speed NE from the rotation speed sensor 22, a battery voltage VB from the voltage sensor 23, a catalyst temperature Tc from the temperature sensor 24, and each electric load. Signals from various sensors and switches such as ON / OFF are input.

The C / U 10 executes various engine controls such as fuel injection control and ignition timing control based on the input signal, and sets a power generation request (target) value according to the operating state and the like. The power generation control (ordinary power generation control) of the alternator 1 is executed so that the (target) value is obtained.
Further, during idle operation, the opening degree of the ISC valve 11 is controlled based on the difference between the engine speed NE and the target rotation speed. Increase correction is performed to prevent the engine speed from being lowered or destabilized.

Further, when the catalyst 14 is at a low temperature such as at the time of start-up, the air-fuel ratio is set to the rich side and the secondary air pump 16 is operated to supply the secondary air to the exhaust passage 13 to raise the catalyst 14. The so-called early activation control of the catalyst to be heated is also executed.
Here, as described above, the secondary air pump 16 that is operated at the time of early activation control of the catalyst has (1) a large electric load at the time of turning on, and (2) a turning-on timing from cranking to complete explosion. In addition to the time when the engine friction is large, (3) since the starter motor (not shown) is often operated at the time of turning on, the engine 2 becomes a heavy load, and the engine speed decreases. It tends to cause instability (startability deteriorates).

On the other hand, if the operation of the secondary air pump 16 is prohibited (stopped) in order to avoid this, the secondary air cannot be supplied when the temperature of the catalyst 14 is required to be raised.
Therefore, in the present embodiment, by stopping the power generation of the alternator 1 during the operation of the secondary air pump 16 at the time of start (immediately after), both early activation of the catalyst and ensuring of good startability can be achieved. ing.

2 and 3 are flowcharts showing the control at the time of engine start executed by the C / U 10, and these are started simultaneously with the start of the engine 2. In general, the engine 2 is determined by detecting the key switch ON, the start of driving a starter motor (not shown), the start of cranking, etc., but the method is not limited.
FIG. 2 is a flowchart of the early activation control of the catalyst.

In S1, the catalyst temperature Tc is detected. Here, the catalyst temperature Tc is detected by the temperature sensor 24, but the operating conditions of the engine 2 are detected based on signals input from various sensors, and the catalyst temperature Tc is estimated from these operating conditions. May be.
In S2, it is determined whether or not the detected (or estimated) catalyst temperature Tc is lower than a predetermined temperature Tc1. The predetermined temperature Tc is set as the activation temperature of the catalyst 14 (or a temperature in the vicinity thereof). If Tc <Tc1 and the catalyst temperature Tc is low (that is, not activated), the process proceeds to S3. On the other hand, when Tc ≧ Tc1 and the catalyst temperature Tc is high, for example, when restarting immediately after the stop, the catalyst 14 has already been activated, so this flow is finished (the catalyst early activation control is not performed). ).

In S3, the air-fuel ratio is set to the rich side, the secondary air pump 16 is set to “ON”, and the secondary air control valve 18 is set to “open”.
In S4, the catalyst temperature Tc is detected (or estimated) again, and it is determined whether or not the catalyst temperature Tc is equal to or higher than the predetermined temperature Tc1. If Tc ≧ Tc1, the process proceeds to S5, and if Tc <Tc1, the temperature rise of the catalyst 14 (secondary air supply) is continued.

In S5, it is determined that the catalyst 14 has been activated because the catalyst temperature Tc has become equal to or higher than the predetermined temperature Tc1, the secondary air pump 16 is turned off, the secondary air control valve 18 is closed, and this flow is performed. finish.
As described above, at the time of starting, when the catalyst temperature Tc is lower than the predetermined temperature Tc1 and the catalyst 14 is not activated, the air-fuel ratio is made rich and the secondary air is introduced into the exhaust passage 13. As a result, the combustion of unburned fuel in the exhaust passage 13 and the oxidation reaction in the catalyst 14 are promoted, the temperature of the catalyst 14 is raised, and the catalyst 14 is activated early.

FIG. 3 is a flowchart of power generation control of the alternator 1 at the time of engine start.
In S11, the catalyst temperature Tc is detected as in S1 of FIG.
In S12, it is determined whether the catalyst temperature Tc is lower than the predetermined temperature Tc1, as in S2 of FIG. If Tc <Tc1, the process proceeds to S13, and if Tc ≧ Tc1, the process proceeds to S15.
In S13, the power generation of the alternator 1 is stopped.

  With the catalyst early activation control (FIG. 2) described above, when the catalyst temperature Tc is lower than the predetermined temperature Tc1, the secondary air pump 16 is turned "ON (operation)" in order to raise the temperature of the catalyst 14. When the secondary air pump 16 changes from “OFF (stop)” to “ON (operation)”, a large electric load is generated particularly at that moment (when the operation of the secondary air pump 16 starts). Also grows. For this reason, the rotational torque of the alternator 1 becomes a heavy load on the engine 2 and causes a decrease in engine speed and instability (deterioration of startability). Therefore, in order to prevent this, the rotation torque of the alternator 1 (load on the engine 2) is reduced by stopping the power generation of the alternator 1 (that is, the power generation amount is set to 0). Here, it is determined whether or not the catalyst temperature Tc is lower than the predetermined temperature Tc1, but it is also determined whether or not the secondary air pump 16 is operating ("ON"). Good. However, in the case of the determination based on the catalyst temperature Tc, since the power generation of the alternator 1 can be stopped before the secondary air pump 16 operates, the engine rotational speed decreases at the start of the operation of the secondary air pump 16 (instability). ) Can be more effectively prevented.

  In S14, it is determined whether or not the elapsed time t1 from the engine start has reached a predetermined time ts1. The predetermined time ts1 is a time at which the influence of power generation on the engine 2 (that is, the rotational torque of the alternator 1) is almost eliminated, and is set according to each vehicle. Specifically, the time when the start is expected to be completed (that is, the time until the complete explosion) is given as an example. If t1 ≧ ts1, the process proceeds to S15. If t1 <ts1, the power generation stop of the alternator 1 is continued.

  In S15, the power generation stop of the alternator 1 is canceled and power generation is started. At that time, it is desirable not to suddenly switch to normal power generation control but to shift to normal power generation control after performing control (gradual excitation power generation) for gradually increasing the power generation amount. This is for smoothly switching the control. And after transfering to normal electric power generation control, the electric power generation amount of the alternator 1 is controlled according to the driving | running state and the electric load thrown in.

  By performing the control as described above, in the present embodiment, the power generation of the alternator 1 is stopped during the operation of the secondary air pump 16 when the engine is started. Thereby, an increase in engine load accompanying the introduction of secondary air (operation of the secondary air pump 16) can be avoided, and a decrease in engine speed and instability can be prevented. Thereby, the secondary air pump 16 can be operated immediately after the start without deteriorating the startability, and the catalyst 14 can be activated early.

FIG. 4 is a timing chart showing a state at the time of starting the engine, and compares the present embodiment (solid line) and the conventional one (broken line).
When the starter motor is rotated for starting and cranking is started (time t1), the battery voltage VB decreases with respect to the initial voltage, but the engine rotational speed NE begins to gradually increase. Here, when the catalyst temperature Tc is lower than the predetermined temperature Tc1, the secondary air pump 16 is turned “ON” in order to activate the catalyst 14 early (time t2). In this case, as shown by the broken line in the figure, the rotation torque (power generation load) of the alternator 1 increases due to the secondary air pump 16 being changed from “OFF” to “ON”, as shown by the broken line in the figure. The load increases and the engine speed is greatly reduced. This may lead to an engine stall in the worst case.

  On the other hand, in the present embodiment, as indicated by the solid line in the figure, since the power generation of the alternator 1 is stopped when the secondary air pump 16 changes from “OFF” to “ON”, the rotational torque of the alternator 1 increases. This does not occur (without being a load on the engine 2), and a decrease in engine speed can be prevented. Thereby, the early activation of the catalyst 14 can be realized without deteriorating the startability. Then, power generation of the alternator 1 is started at a timing (time t3) at which a predetermined time ts1 has elapsed from the start and there is no risk of a decrease in engine rotation speed due to power generation by the alternator 1. At that time, the power generation amount is gradually increased. After performing control (gradual excitation power generation), the routine shifts to normal power generation control (time t4). The secondary air pump 16 is turned “OFF” when the catalyst 14 reaches the activation temperature (or a temperature near the activation temperature). Thereby, control can be smoothly switched from power generation stop to power generation.

  In the above-described alternator power generation control (FIG. 3), power generation by the alternator 1 is stopped (see S13 in FIG. 3), but instead, the power generation amount of the alternator 1 is suppressed. Also good. In this case, for example, when the catalyst temperature Tc is lower than the predetermined temperature Tc1 (or when the secondary air pump 16 is ON), the power generation request (target) value of the alternator 1 is corrected to decrease, An upper limit value (a value that does not affect the engine speed) may be set. Even with this configuration, it is possible to obtain the same effects as in the above embodiment.

Further, when the battery voltage VB is lower than the predetermined voltage (lower limit value), the alternator 1 is not stopped from generating power, or the battery voltage VB falls below the predetermined voltage (lower limit value) while the alternator 1 is stopped generating power. May be configured to cancel the power generation stoppage. This is for avoiding the battery 5 from being in a low charge state and reliably preventing the battery from being discharged.
Further, in the above description, it has been described that the power generation of the alternator 1 is stopped or the power generation amount is suppressed when the catalyst temperature Tc is lower than the predetermined temperature Tc1 or when the secondary air pump 16 is ON. Thus, when the electric load of the vehicle is greater than or equal to a predetermined value or when the engine rotation speed has suddenly decreased (for example, when the amount of decrease per predetermined time is greater than or equal to a predetermined amount), the power generation of the alternator 1 is stopped (or the amount of power generation) May be suppressed). Here, as an electric load of the vehicle, it is conceivable to detect a battery voltage VB, a battery discharge current, and a power generation request (target) value. Even if it does in this way, the same effect as each above-mentioned embodiment is acquired. Furthermore, in the above explanation, change of catalyst temperature Tc, the operating state of secondary air pump 16, the electric load of a vehicle, or engine speed is checked. In addition, the power generation of the alternator 1 is stopped or the power generation amount is suppressed, but the following method may be used.

  For example, more simply, instead of the above-described power generation control of the alternator 1 (FIG. 3), the power generation of the alternator 1 is stopped (or the power generation amount is suppressed) from the start of the engine 2, and then a predetermined period from the engine start t1. The alternator 1 is released when power generation stop (or suppression of power generation amount) after ts1 has elapsed (see FIG. 5), or when the engine rotational speed NE has continued to be at or above the predetermined rotational speed NE1 for at least the predetermined time ts2. It is conceivable to cancel the power generation stop (or suppression of the power generation amount) 1 (see FIG. 6). In this way, the same effects as those of the above embodiments can be obtained while further simplifying the control. Particularly in the latter case, the power generation stop cancellation timing (for example, complete explosion) of the alternator 1 can be determined more stably and accurately, so that the control accuracy is improved.

Of course, the start timing and the release timing of the power generation stop (or suppression of the power generation amount) in the power generation control of each alternator 1 described above may be appropriately combined.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with the effects thereof (a) In the control device for a vehicle generator according to claim 1,
The power generation stop of the vehicle generator or the suppression of the power generation amount is performed before the operation of the secondary air supply means is started.

In this way, it is possible to effectively prevent a decrease (unstabilization) in the engine speed at the start of operation of the secondary air supply means having a particularly large electrical load (OFF → ON).
(B) In the control device for a vehicle generator according to claim 1,
The power generation stop of the vehicle generator or the suppression of the power generation amount is performed when the decrease amount of the engine rotation speed per predetermined time becomes a predetermined amount or more.

In this way, since the power generation is stopped or the amount of power generation is suppressed when the engine speed actually decreases, the control switching (and control load) can be minimized.
(C) In the vehicle generator control device according to claim 2,
The vehicle generator is stopped or the amount of power generation is suppressed until a state where the engine speed is equal to or higher than a predetermined speed continues for a predetermined time or longer.

In this way, it is possible to determine the time when the influence of the power generation load on the engine is small (that is, the time when there is no possibility of a decrease in engine rotation speed) stably and accurately, and the control accuracy can be improved.
(D) In the control device for a vehicle generator as defined in claim 3,
The electric load of the vehicle is a battery voltage, a battery discharge current, or a power generation request (target) value.

  In this way, it is possible to easily detect the electric load of the vehicle.

1 is a system diagram of a vehicle according to an embodiment of the present invention. It is a flowchart of the catalyst early activation control which concerns on one Embodiment. It is a flowchart of the electric power generation control of the generator (alternator) which concerns on one Embodiment. It is a timing chart which shows the state at the time of engine starting. It is a flowchart of the electric power generation control of the generator (alternator) which concerns on another embodiment. It is a flowchart of the electric power generation control of the generator (alternator) which concerns on another embodiment similarly.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Alternator (vehicle generator), 2 ... Engine, 4 ... Electric load, 5 ... Battery, 9 ... Intake passage, 10 ... Control unit (C / U), 13 ... Exhaust passage, 14 ... Exhaust purification catalyst, 15 ... Secondary air supply passage, 16 ... Secondary air pump, 17 ... Pressure regulator, 18 ... Secondary air control valve

Claims (4)

A control device for a vehicle generator driven by an engine,
A control device for a vehicular generator, wherein power generation of the vehicular generator is stopped or a power generation amount is suppressed during operation of secondary air supply means for supplying secondary air to the exhaust system of the engine.   2. The control device for a vehicular generator according to claim 1, wherein the generation of the vehicular generator is stopped or the generation amount is suppressed for a predetermined period from the start of the engine.   3. The control device for a vehicle generator according to claim 1, wherein the power generation stop of the vehicle generator or the suppression of the power generation amount is performed when an electric load of the vehicle is a predetermined amount or more.   The vehicle generator control device according to any one of claims 1 to 3, wherein the power generation amount is gradually increased when the power generation stop of the vehicle generator or the suppression of the power generation amount is released. .