JP2855711B2 - Idle rotation fluctuation control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an idle engine in which a generator is driven by an internal combustion engine so as not to cause unpleasant vibration even if an electric load suddenly increases during idle operation. The present invention relates to a rotation fluctuation control method.

The present invention is useful when applied to, for example, a gasoline vehicle.

<Prior Art> An automobile is provided with an alternate that is rotated by an engine to generate power. While the engine is rotating, the electric power generated by the alternator is supplied to various electric loads, and the battery is charged with sufficient electric power.

In alternators, field coils (field coils)
Is rotated, a three-phase alternating current is generated in a stator coil provided in the stator. The three-phase alternating current is rectified by a three-phase bridge rectifier formed of six diodes and output as a direct current.

The voltage generated by the alternator is proportional to the rotation speed of the rotor and the magnitude of the exciting current flowing through the field coil. It is necessary to keep the voltage to supply to various electric loads and charge the battery constant.Therefore, when the rotation speed becomes high and the generated voltage exceeds the specified value, the excitation current is adjusted by the regulator to adjust the generated voltage. Control.

The regulator adjusts the value of the exciting current flowing through the field coil of the alternator according to the power supplied to various loads. In a transistor-type regulator, the amount of current is controlled by adjusting the duty ratio of the exciting current by turning on and off a power transistor. Thus, by adjusting the exciting current value with the regulator,
The voltage generated by the alternator is adjusted to prevent overcharging and overdischarging of the battery.

This regulator increases the exciting current flowing through the alternator when the electric load increases, and decreases the exciting current when the electric load decreases. Therefore, the torque required to rotationally drive the alternator increases when the electric load is large, and decreases when the electric load is small.

<Problems to be Solved by the Invention> By the way, when the electric load suddenly increases while the engine of the automobile is idling, the exciting current flowing through the alternator increases, the torque for driving the alternator to rotate rapidly increases, and the rotational speed of the engine decreases. In some cases, the rotation of the engine becomes unstable, causing unpleasant vibration to the driver.

During idle operation, the generated torque of the engine is small,
In particular, when the idling rotational speed is set low for the purpose of reducing fuel consumption, the above-described problem is likely to occur.

On the other hand, the driver does not perform any special operation during the idling operation, and also has low interior noise, which makes the driver sensitive to engine noise and rotation fluctuation. In such a case, if the electric load is increased by turning on the cooler or the like, the engine speed decreases, and the driver can clearly recognize the decrease in the engine speed. When the driver feels that the idling speed has decreased, the driver may become uneasy or uncomfortable that a stall may occur. Further, when engine vibration occurs, anxiety and discomfort increase.

The present invention has been made in view of the above-mentioned conventional technology, and provides an idle rotation fluctuation control method that limits the amount of decrease in the number of revolutions of an internal combustion engine even when the electric load increases rapidly during idle operation.

<Means for Solving the Problems> The method of the present invention for solving the above problems is to limit the power generation rate (excitation current duty) of the generator even when the electric load suddenly increases while the engine is idling. Thus, the torque required to rotate the generator is limited to prevent the engine speed from falling below a certain speed.

<Operation> When the engine is idling, the power generation rate is limited even when the electric load increases, and therefore the engine speed does not fall below a preset allowable minimum speed. The preset allowable minimum rotation speed refers to a rotation speed that does not cause unpleasant vibrations felt by the driver even if the engine rotation speed is reduced to this rotation speed.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows a drive system of a gasoline vehicle to which the method of the present invention is applied. As shown in FIG. 1, air is sent to the engine 1 via an air cleaner 2 and an air supply pipe 3. A throttle valve 4 is attached in the middle of the air supply pipe 3,
Throttle valve 4 linked to accelerator pedal (not shown)
Opens and closes. During the idling operation, the throttle valve 4 is fully closed, and the idle switch 5 detects this fully closed state (idling operation state). The bypass pipe 6 connects the upstream side and the downstream side of the air supply pipe 3 so as to bypass the throttle valve 4. A needle valve 8 biased by a compression coil spring 7 is provided in the bypass pipe 6, and the bypass pipe 6 is opened and closed by the needle valve 8 by duty driving of a solenoid 9.

On the other hand, the alternator 10 is rotated and driven by the engine 1 to generate electric power, send electric power to various electric loads 11, and charge the battery 12 with surplus electric power. The battery 12 sends power to the electric load 11 when the power generated by the alternator is insufficient or power is not generated. The distributor 13 is provided with a crank angle sensor 14.

The electronic control unit 15 receives detection signals from various sensors such as the idle switch 5 and the crank angle sensor 14, and controls the solenoid 9 and each control device. In carrying out the method of the present invention, it plays a central role of control.

Here, the electric system of the drive system shown in FIG. 1 will be described with reference to FIG. As shown in FIG.
The main components are a power generation unit 10-1 having a stator coil SC and a field coil FC, a rectifier 10-2 formed of a diode, and a regulator 10-3. The regulator 10-3 changes the duty ratio of the exciting current flowing through the field coil FC in accordance with the voltage of the battery 12 and the electric load capacity used, so that the
The generated current value according to 10-1 is adjusted. In other words, when the battery voltage decreases or the used electric load capacity increases, the duty ratio is increased to increase the generated current,
In the opposite situation, the duty ratio is lowered to make the generated current smaller. Then, the duty ratio of the exciting current flowing through the field coil FC is detected by the electronic control device 15 via the FR terminal. When the G terminal of the regulator 10-3 is grounded via the control unit 16 by a command from the electronic control unit 15, the field coil FC
And the generated current becomes zero, and the power generation is cut off. The regulator 10-3 adjusts the duty ratio according to the battery voltage and the used electric load capacity. However, the regulator of the type that adjusts the duty ratio based only on the used electric load capacity without referring to the battery voltage is used. There is also.

In FIG. 2, reference numeral 17 denotes an ignition switch,
18 is a charge lamp.

Next, the basic technology supporting the method of the present invention will be described with reference to FIGS.
This will be described with reference to the drawings.

FIG. 3 shows the relationship between the FR terminal duty and the G terminal ground duty. The FR terminal duty indicates the duty ratio of the exciting current detected at the FR terminal. When the exciting current actually flowing through the field coil FC is continuous, the FR terminal duty becomes 100% and the field coil FC When no exciting current is flowing through
The FR terminal duty becomes 0%. This FR terminal duty is proportional to the power generation rate of the alternator. The G terminal grounding duty indicates the rate at which the G terminal is grounded. When the G terminal is continuously grounded, the G terminal grounding duty becomes 100%, and when the G terminal is not grounded at all, the G terminal grounding duty becomes 0%. Become. When the G terminal is grounded as described above, power generation is forcibly cut off regardless of the control state of the regulator 10-3.

FIG. 3 (a) shows the characteristics when the regulator 10-3 permits 100% power generation. It can be seen that as the G terminal ground duty is reduced, the FR terminal duty (power generation rate) increases. . FIG. 3 (b) shows the regulator 10−
No. 3 shows the characteristic when the power generation is limited to 50%. It can be seen that the FR terminal duty (power generation rate) does not become 50% or more even if the G terminal grounding duty is 50% or less. FIG. 3C shows the characteristics when the regulator 10-3 limits the power generation to 25%.
It can be seen that the FR terminal duty (power generation rate) does not become 75% or more even if the percentage is less than%. For this reason, "If the G terminal grounding duty is controlled, the maximum value of the FR terminal duty (power generation rate) can be controlled."
Is obtained as a conclusion.

FIG. 4 shows the relationship between the FR terminal duty (power generation rate) and the driving torque required to rotationally drive the alternator. The relationship between the FR terminal duty (power generation rate) and the alternator driving torque is one-to-one. Something is ".

From the conclusions obtained from FIG. 3 and FIG. 4, the following findings were found. That is, the regulator generally controls the power generation rate to increase when the electric load increases, and the alternator driving torque increases when the power generation rate increases (see FIG. 4).
As a result, the engine speed decreases during idling, causing unpleasant vibration. Therefore, during idling, the upper limit of the power generation rate is limited by the G terminal ground duty (see FIG. 3), and if the alternator driving torque is limited, the engine speed does not fall below a certain speed. By doing so, no unpleasant vibration is caused. If the limit value is strict, even if the electric load suddenly increases during idling, the driver does not recognize that the engine speed has decreased. When the power generation rate is limited, the power is insufficient for the sudden increase in the electric load, but the shortage is covered by the battery.

Next, two embodiments of the idle rotation fluctuation control method of the present invention, which is performed by the electronic control device 15 as the center of control, will be described.

First, a first embodiment of the present invention will be described with reference to FIG. 2 and FIG. 5 which is an operation flowchart. A control map as shown in Table 1 below is set in the electronic control unit 15 in advance.

In Table 1 above, the engine speed N ₁ to N _n is the rotational speed of the idling speed region, the rotational speed N ₁ in which is the lowest rotational speed, the rotation as the N _2, N ₃ ... become The numbers rise,
Rpm N _n is the maximum rotation speed. Each such rotation speed N ₁ ~
G terminal ground duties G _{1 to} G _n are determined corresponding to N _n respectively. And at each rotational speed N ₁ to N _n, if its G terminal corresponding to the rotational speed grounding duty G ₁ ~G _n,
The upper limit of the FR terminal duty (power generation rate) is limited according to the G terminal grounding duty, so that the torque required to rotate the alternator does not become larger than a certain value, and the engine speed is equal to or less than the preset allowable minimum speed. The control map is designed so that the control map does not occur.
The “permissible minimum rotation speed” as used herein is a rotation speed that does not cause vibration that gives a driver discomfort even if the engine rotation speed decreases to this rotation speed. When the engine speed is lower than the engine speed, unpleasant vibrations are generated from the engine.

Thus, for example the G terminal ground duty when the engine speed is N ₂ so as to G _2, the electronic control unit 15
When the control unit 16 is controlled by, the upper limit of the FR terminal duty (power generation rate) is limited. When the electric load is small, the amount of power generation is controlled by the regulator 10-3 according to the electric load. But even if the electric load increases rapidly, FR terminal duty can not exceed the upper limit defined by the G terminal ground duty G _2. Therefore, even if the electric load suddenly increases, the torque required to rotate the alternator will not exceed a certain value, and the engine speed will not be lower than the minimum allowable speed, and unpleasant vibration from the engine will occur. Absent.

Electronic control device using the control map as described above
15 performs the following control (see FIG. 5).

(1) First, the electronic control unit 15 determines whether or not the engine 1 is in idle operation (steps 1 and 2). That is, when the idle switch 5 detects that the throttle valve 4 is closed and the crank angle sensor 14 detects that the crank angle is in the idle rotation region, it is determined that the idle operation is being performed.

(2) If the engine is idling, the electronic control unit 15 inputs the engine speed N at that time from the crank angle sensor 14 (step 3).

(3) Next, the G terminal ground duties G _{1 to} G _n corresponding to the input engine speed N (N _{1 to} N _n ) are read from the control map (step 4).

(4) the electronic control unit 15, so that the read G terminal ground duty (one of G ₁ ~G _n), to the duty control control unit 16 (Step 5). With this configuration, as described above, even if the electric load suddenly increases, the engine speed does not fall below the allowable minimum speed, and unpleasant engine vibration does not occur.

(5) After a certain timer count (step 6),
The above control is performed periodically.

(6) When the idling operation stops during the control, the electronic control unit 15 stops the duty control of the control unit 16 and sets the G terminal ground duty to 0% (step 7).

Next, a second embodiment of the present invention will be described with reference to FIG. 2, an operation flow diagram of FIG. 6, and a control characteristic of FIG. When controlling the second embodiment, the electronic control unit
In FIG. 15, a control map as shown in the following Table 2 is set in advance.

As shown in Table 2 above, G corresponds to each mode in which the engine speeds N _{1 to} N _n in the idling speed region and a number of FR terminal grounding duties (power generation rates) α to 100 are combined.
Terminal ground duty Is set in advance. And in each mode,
If the G terminal ground duty is set, the engine speed will not fall below the allowable minimum speed even if the electric load increases suddenly, and the engine speed will have a predetermined maximum allowable speed fluctuation. The control map is set to be settled within the width. The “permissible maximum rotation fluctuation range” as used herein refers to an engine rotation speed fluctuation range of which the driver does not notice the change even when the engine speed changes.

FIG. 7 shows the relationship between the two parameters extracted from the three-dimensional control map shown in Table 2. That is, FIG. 7A shows the relationship between the FR terminal duty (power generation rate) and the engine speed, and FIG. 7B shows the relationship between the G terminal grounding duty and the engine speed.
FIG. 4C shows the relationship between the G terminal ground duty and the FR terminal ground duty. As can be seen from FIG. 7 (a), when the electric load is fixed and considered, when the engine speed is low, the power generation capacity of the alternator is small, so the power generation rate increases, and as the engine speed increases, the power generation capacity increases. Accordingly, the regulator automatically lowers the duty of the field current to lower the power generation rate and try to keep the power generation constant (an amount corresponding to the electric load). As can be seen from FIG. 7 (b), when the FR terminal duty (power generation rate) is fixed and considered, the G terminal grounding duty is controlled to a value obtained by adding the allowable rotation fluctuation width β to the current FR terminal duty. I do. When the allowable rotation fluctuation width β is converted into the G terminal ground duty, the margin of the G terminal ground duty is small because the engine output torque is small in the region where the engine speed is low, but the output torque of the engine increases as the engine speed increases. G
The terminal ground duty margin can be increased. Further, as can be seen from FIG. 7 (c), when the engine speed is fixed, the G terminal grounding duty with respect to the FR terminal duty is set as a value in consideration of the allowable rotation fluctuation width β.

Thus, for example the G terminal ground duty when the engine speed is FR terminal duty alpha + 1 in N ₂ As in the electronic control unit 15, the control unit
By controlling 16, the upper limit of the FR terminal duty (power generation rate) is limited. When the electric load is small, the amount of power generation is controlled by the regulator 10-3 according to the electric load.
However, even if the electric load suddenly increases, the FR terminal duty is the G terminal grounding duty. It cannot exceed the upper limit specified in. Therefore, even if the electric load suddenly increases, the torque required to rotate the alternator will not exceed a certain value, and the engine speed will not be lower than the minimum allowable speed, and unpleasant vibration from the engine will occur. Absent. And G terminal ground duty Is a value that takes into account the allowable rotation fluctuation range, so even if the electric load increases rapidly, the engine rotation speed fluctuation range is small, and this fluctuation is not noticed by the driver.

Electronic control device using the control map as described above
15 performs the following control (see FIG. 6).

(1) First, the electronic control unit 15 determines whether or not the engine 1 is in idle operation (steps 1 and 2). That is, when the idle switch 5 detects that the throttle valve 4 is closed and the crank angle sensor 14 detects that the crank angle is in the idle rotation region, it is determined that the idle operation is being performed.

(2) If the engine is idling, the electronic control unit 15 inputs the engine speed N and FR terminal duty at that time from the crank angle sensor 14 (step 3).

(3) Next, the input engine rotation speed N and the G terminal ground duty corresponding to the FR terminal duty mode are read from the control map (step 4).

(4) The electronic control unit 15 controls the duty of the control unit 16 so that the read G terminal ground duty is obtained (step 5). This way,
As described above, even if the electric load suddenly increases, the engine speed does not fall below the allowable minimum speed, no unpleasant engine vibration occurs, and the engine speed fluctuation range falls within the allowable maximum speed fluctuation range.

(5) After a certain timer count (step 6),
The above control is performed periodically.

(6) When the idling operation stops during the control, the electronic control unit 15 stops the duty control of the control unit 16 and sets the G terminal ground duty to 0% (step 7).

In the above-described embodiment, the idling rotation fluctuation control method of the present invention is executed by using the electronic control unit 15. However, the method of the present invention may be executed by using a dedicated controller. The controller may be built in the alternator. Also, the engine speed is
The number of revolutions of the alternator may be obtained by multiplying the required number.

<Effects of the Invention> As described above in detail with the embodiments, according to the present invention, the upper limit of the power generation rate (excitation current duty) of the alternator is limited even when the electric load suddenly increases during the idling operation. Therefore, the torque required to rotate the alternator does not exceed a certain value, so that the number of revolutions of the engine does not decrease so much and the engine does not cause unpleasant vibration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a drive system of a gasoline vehicle, FIG. 2 is a circuit diagram showing an electric system of a gasoline vehicle, FIG. 3 is a characteristic diagram showing a relationship between an FR terminal duty and a G terminal ground duty, and FIG. FIG. 5 is a characteristic diagram showing the relationship between the alternator driving torque and the FR terminal duty, FIG. 5 is a flowchart showing the procedure of the first embodiment of the present invention, and FIG.
FIG. 7 is a characteristic chart showing the interrelationship of the control parameters of the second embodiment. In the drawings, 1 is an engine, 5 is an idle switch, 10 is an alternator, 10-3 is a regulator, 11 is an electric load, 14 is a crank angle sensor, 15 is an electronic control unit, and 16 is a control unit.

Claims (2)

(57) [Claims] A generator having a characteristic in which a torque required for rotating and driving the engine is proportional to an exciting current duty inputted to a field coil; A power generation limiting means for generating a control signal capable of limiting an upper limit of the exciting current duty which increases or decreases in accordance with an increase or decrease in load. For the rotational speed value, an upper limit value corresponding to the minimum permissible rotational speed of the engine of the exciting current duty is stored in advance, and the rotational speed of the engine is detected. Limiting the exciting current duty by the control signal so as not to exceed the upper limit corresponding to the rotation speed. Idle speed variation control method according to symptoms. A generator having a characteristic in which a torque required for rotationally driving the engine is proportional to an exciting current duty input to the field coil, and an electric power input to the generator. A power generation limiting means for generating a control signal capable of limiting an upper limit of the exciting current duty which increases or decreases in accordance with an increase or decrease in load. The control signals corresponding to the minimum permissible rotation speed and the maximum permissible rotation speed variation of the engine are stored in advance for a plurality of modes in which the rotation value and the plurality of values of the excitation current duty are combined, and Number and the excitation current duty are detected, and when the engine is idling,
An idle speed fluctuation control method, wherein an upper limit of the exciting current duty is limited by the control signal corresponding to the detected engine speed and the exciting current duty.