JPS6392232A - Method of controlling output voltage of ac generator for internal conbustion engine - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention particularly relates to a method for controlling the output voltage of an alternator for an internal combustion engine mounted on a vehicle.

(Prior art and its problems) Conventionally, alternating current generators (hereinafter referred to as ACG) that are driven by a vehicle internal combustion engine and charge a vehicle battery have been used.
In order to adjust the ACG load on the engine, the amount of power generation can be controlled according to the operating state of the engine (the magnitude of the electrical load on the engine, the vehicle speed, the warm-up state of the engine, etc.). For example, Jikoko Sho 55-52779
The publication states that in order to increase the engine braking effect, the set voltage of the ACG output voltage control device can be raised to a high level when the vehicle speed is decelerated, for example by changing the amount of current supplied to the field winding of the ACG. ACG control for voltage change
A method of accelerating charging of an on-vehicle battery during deceleration is disclosed.

However, in such conventional methods, no measures are taken when the engine is not sufficiently warmed up and ready for self-sustaining operation (complete explosion state). There has been a problem in that the engine speed does not increase quickly depending on the load, or stalls tend to occur, resulting in poor startability and insufficient engine performance at all times.

(Means for Solving the Problems) The present invention has been made to solve the problems of the prior art, and the first invention is a method for setting the output voltage of an alternator driven by an internal combustion engine. In the method for controlling the output voltage of an alternator for an engine, the set voltage of the output voltage of the alternator is set to a low value when starting the engine or during a predetermined period after starting the engine. The second invention is characterized by the following.

In a method for controlling the output voltage of an alternator for an internal combustion engine in which a set voltage of an output voltage of an alternator driven by an internal combustion engine is changed according to the operating state of the engine, the temperature of the engine after starting the engine is set to a predetermined set temperature. or less, and the output voltage of the alternator is set to a low value until the rotational speed of the engine reaches or exceeds a predetermined value.
By lowering the output voltage of G under certain conditions.

The purpose is to improve the startability of the engine at or immediately after starting.

(Example) Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

Figure 1 shows an example of how ACGI is used.
GI has a fixed advance volume! The three-phase AC output generated by the stator winding 2 is rectified by a rectifier 4 and supplied to a battery 5, and is also supplied to an electrical load 7 via a main fuse box 6. It has become so. The voltage V of the battery 5 is compared with a predetermined voltage set by a variable resistor 9 or 10 in a comparator 8, and the output of the comparator 8 controls the energization of the field winding 3. I try to do it.

The selection of the variable resistor 9 or 1o is made by a changeover switch 11, and the changeover of this changeover switch 11 is made in accordance with the output of an ECU 12, which is connected to the main fuse box 6. The variable resistor 9 or 10 is outputted in accordance with the current value detected by a current detection device 13 provided therein, that is, the magnitude of the electrical load. That is, when the electrical load is small, the changeover switch 11 is switched to the variable resistor 9 side, and when the electrical load is large, the changeover switch 11 is switched to the variable resistor 10 side. Also, E
The CU 12 detects the operating state of the engine. For example, when the engine is in a deceleration state, the changeover switch 11 is switched to the variable resistor 9 side, regardless of the detected value of the current detection device 13.

Therefore, when the electrical load is small, the amount of power generated by the generator is low until the voltage V of the battery 5 reaches a predetermined low voltage, so the battery 5 is slightly discharged, while the engine load is reduced. Then, when the engine is in a deceleration state, the voltage V of the battery 5 is switched to a predetermined high voltage, the amount of power generated by the generator becomes a high level, and charging of the battery 5 is promoted. That is, the kinetic energy of the vehicle is converted into electrical energy during deceleration, thereby improving the fuel efficiency of the vehicle.

FIG. 2 shows the output voltage control procedure of ACGl, and when the execution of this control procedure starts, step 10
In step 1, it is determined whether the electrical load applied to the engine exceeds a predetermined value, and if the determination result is affirmative (Yes), the output voltage of the ACGl of the vehicle is set to a low value. Since the battery 5 will be in a slightly discharged state, in order to avoid this, the process passes through steps 106 to 108, which will be described later, and proceeds to step 109, where the setting voltage of the output voltage of ACGl is set to a high setting value, for example 14.
Set to 5 volts. This set value is slightly higher than the output voltage of the battery 5 (eg 12 volts).

If the determination result in step 101 is negative (NO), the process proceeds to step 102, where it is determined whether the vehicle speed is, for example, 50 km/h or more, and if the determination result is affirmative (Yes), Since this cannot be said to be a low engine load state, the process proceeds to step 109 and the output voltage of ACGl is set to 14.5 volts, similar to the affirmative (Yes) determination result in step 101.

If the determination result in step 102 is negative (No), the process proceeds to step 103, where it is determined whether or not the engine cooling water temperature Tw is below a predetermined set temperature (for example, 70°C). If the result is negative (NO), the process proceeds to step 104, where it is determined whether the vehicle speed is decelerating or not, and the determination result is affirmative (Yes).
If so, the process passes through steps 106 to 108 and proceeds to step 109 in order to charge the battery 5 with ACGl by effectively utilizing the kinetic energy of the engine, and the set voltage of the output voltage of ACGl is set to 14.5 volts. is set to If the determination result in step 104 is negative (No), the process proceeds to step 105 and the set voltage of the output voltage of ACGl is set to 12.5 volts in order to reduce the load on the engine.

On the other hand, the determination result in step 103 is affirmative (Yes).
), this means that the engine has not warmed up sufficiently quickly, so the process proceeds to step 106, where it is determined whether or not the engine is cranking.

If the determination result in step 106 is affirmative (Yas), it is necessary to reduce the load on the engine, so the process proceeds to step 105, where the set voltage of the output voltage of ACGl is set to a second set value, e.g. On the other hand, if the determination result in step 106 is negative (NO), the process advances to step 107 and determines whether a predetermined time (for example, 2.5 seconds) has elapsed after cranking. If this determination is made and the determination result is negative (NO), the engine rotation is still in an unstable state, and the engine load is low as in the case of an affirmative (Yes) determination result in step 106. It is necessary to reduce the
Proceeding to step 5, the set voltage of the ACGI output voltage is set to 12.5 volts. Further, if the determination result in step 107 is affirmative (Yes).

Proceeding to step 108, the engine cooling water temperature Tw representing the engine temperature is set to a predetermined set temperature (for example, 20°C).
A determination is made as to whether it is less than or equal to

If the determination result is affirmative (Yes).

For example, since the viscosity of engine oil is high, it is necessary to reduce the load on the engine.
．． On the other hand, if the determination result in step 108 is negative (NO), the viscosity of the oil is low, so the process proceeds to step 109 and the set voltage of the ACGI output voltage is set to 1.
Set to 4.5 volts.

If the determination result in step 108 is affirmative (Yes), the process proceeds to step 110, where the engine speed Ne is a value indicating that the engine is in a tentatively complete explosion state, for example, slightly higher than the idling speed. rotation speed (12
If the result of the determination is affirmative (Yes), it is necessary to reduce the load on the engine, so in step 105 the AC
The output voltage of G1 is set to 12.5 volts. On the other hand, if the determination result in step 110 is negative (NO), it can be considered that the engine is in a complete explosion state, so the set voltage of the output voltage of ACGl is set to 14.5 volts.

FIG. 3 is a graph showing engine startability by showing changes in engine speed Ne with respect to elapsed time t, and in the case of the embodiment of the present invention configured as described above (
A comparison between a curve P shown by a solid line and a conventional configuration (curve Q shown by a broken line) is shown. According to this, in the conventional case, during a certain period of time after cranking tc, the engine speed does not rise immediately but repeats small fluctuations, and at a certain point ts, the engine speed reaches zero. A so-called stall occurs. Furthermore, even if no stall occurs, the rate of increase in engine speed after a certain period of time from the cranking time tc is small, and it takes a long time to reach a complete explosion state.

On the other hand, in the case of this embodiment, during cranking tc
Immediately after that, the engine speed increases to a value close to the rotation speed No. (for example, 120 rpm) that indicates a complete explosion state,
This indicates that it will quickly become a complete explosion.

Note that the engine startability shown in FIG. 3 is shown when the engine cooling water temperature Tw is -30°C.

(Effects of the Invention) As described above, according to the first invention, the output voltage of the engine alternator changes the set voltage of the output voltage of the alternator driven by the internal combustion engine according to the operating state of the engine. In the control method, the setting voltage of the output voltage of the alternator is set to a low value when starting the engine or during a predetermined period after starting, so that the AC Gl By reducing the load on the engine, it reduces the load on the engine when starting the engine and more reliably prevents the engine from stalling.
As a result, the startability of the engine can be improved.

According to a second aspect of the present invention, in a method for controlling an output voltage of an alternator for an internal combustion engine, the output voltage of an alternator driven by an internal combustion engine is changed in accordance with the operating state of the engine. Since the configuration is such that the output voltage of the alternator is set to a low value until the temperature of the engine after starting is below a predetermined set temperature and the rotational speed of the engine is above a predetermined value, the first In addition to the effects of the invention described above, the present invention has the effect of improving the operational stability of the engine after starting the engine.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of the use of an ACG, FIG. 2 is a flowchart explaining an embodiment of the method for controlling the output voltage of an ACG for an internal combustion engine according to the present invention, and FIG. It is a graph which compares and explains this case and the conventional case. 1...ACG (alternating current generator), 2...Stator winding. 3... Field winding, 6... Comparator, 13... Current detection device.

Claims (1)

[Claims] 1. In a method for controlling the output voltage of an alternator for an engine in which the set voltage of the output voltage of an alternator driven by an internal combustion engine is changed according to the operating state of the engine, the method includes: Alternatively, a method for controlling the output voltage of an alternator for an internal combustion engine, characterized in that a set voltage of the output voltage of the alternator is set to a low value during a predetermined period after starting. 2. In an output voltage control method for an alternator for an internal combustion engine, the set voltage of the output voltage of the alternator driven by the internal combustion engine is changed according to the operating state of the engine,
The output voltage of the alternator is set to a low value until the engine temperature is below a predetermined set temperature and the engine rotational speed is above a predetermined value after the engine is started. A method for controlling the output voltage of an alternator for an internal combustion engine.