JP4130609B2 - Automotive power circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automobile power supply circuit.
[0002]
[Prior art]
Conventionally, for example, an AC generator is connected to an engine, and a battery is charged by an AC voltage of an AC generator that rotates in conjunction with the rotation of the engine (see, for example, Patent Document 1).
[0003]
For example, FIG. 5 shows an example in which a power circuit of a small motorcycle is configured as described above. In the figure, a power input terminal 2a of a battery voltage control circuit 2 is connected to a voltage terminal 1a of an AC generator (ACG), and a DC load 3 and a battery 4 are connected to a charging terminal 2b of the battery voltage control circuit 2. Yes.
[0004]
In the voltage control circuit 2, the thyristor SCR1 is connected in a direction in which a current flows from the power input terminal 2a to the charging terminal 2b. The thyristor SCR1 is controlled by a battery voltage detection circuit 5 connected to its gate. The battery voltage detection circuit 5 detects the voltage (battery voltage) at the charging terminal 2b, and turns on the thyristor SCR1 when the battery voltage is lower than a predetermined lower limit value.
[0005]
The cathode of the lamp lighting thyristor SCR2 is connected to the power input terminal 2a, and the anode of the thyristor SCR2 is connected to the lamp connection terminal 2c. The lamp connection terminal 2c is connected to a lamp 6, for example a headlamp, having one end grounded. The thyristor SCR2 is controlled by a lamp voltage detection circuit 7 connected to its gate. The lamp voltage detection circuit 7 detects the voltage (negative voltage) at the lamp connection terminal 2c, and turns off the thyristor SCR2 when the lamp 6 reaches a predetermined voltage or higher to control the lighting of the lamp 6. .
[0006]
In addition, a capacitor C1 is connected to a node between the thyristor SCR1 and the charging terminal 2b via a diode D1 that is directed to pass a current toward the ground side. A power supply terminal 2d for supplying voltage to the external engine control load 8 is taken out from the node of the diode D1 and the capacitor C1. The engine control load 8 is composed of various electric components corresponding to the digitization of engine control systems in recent years.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-149562 (right column on page 3, FIG. 1)
[0008]
[Problems to be solved by the invention]
However, in small motorcycles, a small-capacity battery is used, and the battery may be in a so-called battery disconnection state such as battery voltage drop or battery line disconnection due to insufficient maintenance. A kick pedal that enables the engine to rotate from the outside is provided so that the engine can be started even in such a case.
[0009]
On the other hand, in recent small motorcycles, the engine control load 8 and the like electronically controlled as described above are used from the viewpoint of improving fuel efficiency, and the load on the battery tends to increase more and more. Under such circumstances, there is a problem that engine start-up becomes more difficult if the battery falls off. And when the battery voltage is insufficient, the starter cannot start as expected and kick starts. In this case, the rotation speed of the alternator is low, so only a low voltage may be generated. A sufficient voltage cannot be supplied to the engine control load 8. As a countermeasure, the above-described capacitor C1 is used as a pseudo-stabilized power source.
[0010]
The potential of the terminal 2b in the case of the battery undervoltage condition is as shown by the solid line in FIG. The capacitor C1 is charged by the positive voltage waveform, but is discharged to drive the engine control load 8 in the waveform disappearance section (between the positive half-wave waveform), so the potential is shown by an imaginary line in the figure. It becomes like this. Therefore, since it is necessary to increase the capacity of the capacitor C1 in order to ensure stable driving of the engine control load 8, there is a problem that the apparatus is increased in size and cost.
[0011]
[Means for Solving the Problems]
In order to solve such a problem and to reduce the capacity of a capacitor serving as a pseudo power source at the time of start-up due to insufficient battery voltage, etc., in the present invention, an AC generator driven by an engine and A battery, a positive voltage drive circuit for charging the battery with a positive voltage waveform of the AC generator and driving a first positive voltage drive load, and an engine connected in parallel with the first positive voltage drive load A power supply circuit for an automobile having a second positive voltage drive load for controlling and a negative voltage drive circuit for driving a negative voltage drive load by a negative voltage waveform of the AC generator, and detecting a state of the battery A battery state detecting means; and a full-wave rectifying means for switching the output of the AC generator to full-wave rectification and supplying the output to each positive voltage drive load, and the battery voltage is insufficient In the case of detection, there is provided start-up control means for controlling supply of the negative voltage to the negative voltage drive load by the negative voltage drive circuit and performing full wave rectification by the full wave rectification means. It was supposed to be.
[0012]
According to this, when the battery voltage shortage is detected, the supply of the negative voltage to the negative voltage drive load by the AC generator is stopped and switched to full wave rectification. Can provide all of the output. As a result, even when the rotational speed of the AC generator is low and the power generation output is small, a double power capacity is obtained compared to the case where only a half-wave positive voltage is supplied, and the negative voltage drive load is driven. To stop, for example, in a small motorcycle that starts by kicking when the battery voltage is insufficient, sufficient power can be supplied even when kicking to a positive voltage drive load without increasing the capacity of the pseudo power supply capacitor as a substitute for the battery. Can be supplied. When the second positive voltage drive load is an engine control load constituted by a circuit or a part that performs engine control, power supply with the double power capacity can be supplied to the engine control load. Sufficient power can be easily secured.
[0013]
In particular, the start-up control means includes a positive voltage grounding switching element that grounds the AC generator ground terminal when the positive voltage is output, and a negative voltage that grounds the AC generator voltage terminal when the negative voltage is output. It is preferable to include a switching element for grounding and a switching element for full-wave rectification for full-wave rectifying a negative voltage and outputting it to each positive voltage drive load when the negative voltage is output.
[0014]
According to this, with a small element configuration, the negative voltage supply is stopped and full-wave rectification is performed at the start, and the normal state at the high rotation speed after the start (each half wave of the positive and negative voltages is applied to each positive and negative voltage drive load). Supply state).
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail based on specific examples shown in the accompanying drawings.
[0016]
FIG. 1 is a diagram showing a power circuit of a small motorcycle to which the present invention is applied. In addition, the same code | symbol is attached | subjected to the part similar to FIG. 5 shown in the prior art example, and the detailed description is abbreviate | omitted. Even in this battery voltage control circuit 2, a power input terminal 2a, a charging terminal 2b, a lamp connection terminal 2c, and a power terminal 2d are provided. As in the conventional example, the power input terminal 2a is connected to the AC generator 1. A voltage terminal 1a is connected, and a DC load 3 as a first positive voltage drive load and a battery 4 are connected to the charging terminal 2b. An FI load 8 and a control circuit (ECU) 9 as a second positive voltage drive load are connected to the power supply terminal 2d in parallel with the DC load 3, and a negative voltage drive load is connected to the lamp connection terminal 2c. For example, a lamp 6 that is a headlamp is connected. The FI load 8 is an engine control load such as a spark plug, an ignition coil, and an electronic ignition control circuit. The thyristor SCR1 and the battery voltage detection circuit 5 constitute a positive voltage drive circuit.
[0017]
The battery voltage control circuit 2 according to the present invention is provided with a ground input terminal 2e, and a ground terminal 1b of the AC generator 1 is connected to the ground input terminal 2e. A thyristor SCR3 as a full-wave rectifying switching element is provided between the ground input terminal 2e and the charging terminal 2b, and its anode is connected to the ground input terminal 2e and its cathode is connected to the charging terminal 2b. . Further, the cathode of a thyristor SCR4 whose anode is grounded as a negative voltage grounding switching element is connected to the node of the power supply input terminal 2a and the thyristor SCR1, and the ground input terminal 2e and the node of the thyristor SCR3 are grounded for a positive voltage. It is grounded via a transistor FET1, which may be a FET as a switching element.
[0018]
The gates of the thyristors SCR3 and SCR4 and the transistor FET1 are controlled by a control circuit (ECU) 9. The control circuit 9 is connected to the power supply terminal 2d to detect the battery voltage as battery state detection means, and is connected to the lamp voltage detection circuit 7 to control the thyristor SCR2. The thyristor SCR2 and the ramp voltage detection circuit 7 constitute a negative voltage drive circuit.
[0019]
The control circuit 9 also receives a rotational speed detection signal from a pickup coil 10 provided in the AC generator 1 for detecting the engine rotational speed as a start detection means.
[0020]
Next, the control procedure by the battery voltage control circuit 2 according to the present invention will be described below. The target small motorcycle can be started by kicking a kick pedal that can be engaged with a crankshaft of an engine. In the description of the illustrated example, it can be started by a starter motor, but may be always kick-started.
[0021]
When the charge amount of the battery 4 is sufficient, the engine can be started by the starter motor by turning on a starter switch (not shown). In this case, the voltage necessary for driving the engine control load 8 can be supplied from the battery 4.
[0022]
On the other hand, since the starter motor cannot start the battery 4 in an insufficient voltage state when the charge amount of the battery 4 decreases or the battery comes off, the kick pedal is kicked and started as described above. To do.
[0023]
In the illustrated example, a rotation speed signal from the pickup coil 10 is input to the control circuit 9. It should be noted that by setting a threshold value N1 (for example, 1000 rpm) for detecting that the engine is being started, if the rotational speed detection value by the pickup coil 10 is N1 or less, the engine is being started. Can be determined. Further, the control circuit 9 detects the voltage of the charging terminal 2b, thereby detecting the voltage of the battery 4 and setting a battery voltage lower limit value sufficient to drive the engine control load 8, for example. When the voltage detection value of 4 is less than or equal to the battery voltage lower limit value, it is determined that the voltage is insufficient.
[0024]
The control by the control circuit 9 will be described below with reference to the time chart of FIG. Note that the thyristor SCR1 is brought into a normal driving state by turning on the ignition switch.
[0025]
If it is determined that the battery voltage is lower than the lower limit value at the time of starting the engine, the thyristor SCR2 is stopped and the thyristors SCR3 and SCR4 are turned on as shown on the side corresponding to (N ≦ N1) in FIG. Then, the transistor FET1 is turned off. Thereby, since the thyristor SCR2 is in a stopped state, it is possible to prevent a current from flowing through the lamp 6.
[0026]
In this way, when a positive voltage waveform is output from the AC generator 1, a current can flow from the ground side via the parasitic diode D2 of the off-state transistor FET1, so the solid line arrow in FIG. As shown in FIG. Further, when a negative voltage waveform is output from the AC generator 1, since the thyristors SCR3 and SCR4 are turned on, a current can flow as indicated by the dashed arrows in FIG. Therefore, a full-wave rectified voltage output is obtained as shown by the waveform of the terminal 2b in FIG.
[0027]
As described above, the thyristor SCR1, the battery voltage detection circuit 5, and the transistor FET1 constitute start-up control means for outputting the full-wave rectified waveform of the AC generator 1 during start-up.
[0028]
In the case of half-wave rectification, a discharge time of one or more peaks (1/2 period) of the AC waveform occurs, and the potential of the capacitor is shown by an imaginary line in the figure in the same manner as shown in the conventional example. Since the discharge occurs, the fluctuation range of the potential is large. On the other hand, by full-wave rectification, the potential of the capacitor C1 is frequently charged by a continuously generated positive voltage waveform as shown by the solid line shown at the terminal 2d in FIG. Since the discharge time is short, the output is approximately twice that of half-wave rectification. Therefore, even when the load capacity is large, a small-capacitance type capacitor is sufficient, and it is not necessary to use a large capacitor C1 used as a measure against battery voltage shortage or battery disconnection.
[0029]
In addition, a threshold value N2 (for example, 1500 rpm) for detecting that the rotational speed is equal to or higher than the idling rotational speed is set. When the rotational speed detected value by the pickup coil 10 is equal to or higher than N2, after idling (N ≧ N2) Is determined by the control circuit 9 to be in the normal operation state. In this case, as shown on the side corresponding to (N ≧ N2) in FIG. 2, the thyristor SCR2 is driven, the thyristors SCR3 and SCR4 are turned off, and the transistor FET1 is turned on.
[0030]
By doing so, when a positive voltage waveform is output from the AC generator 1, current can flow from the ground side through the transistor FET1 in the on state, and therefore, as shown by the solid line arrow in FIG. Current flows through Further, when a negative voltage waveform is output from the AC generator 1, the thyristors SCR3 and SCR4 are off and the thyristor SCR2 is in a driving state, and therefore, as shown by the broken arrow in FIG. Current can flow. Therefore, as shown on the side corresponding to (N ≧ N2) in FIG. 2, the positive voltage waveform is output as a half wave as shown by the waveform of the terminal 2b, and the negative voltage waveform is changed to the waveform of the terminal 2c. As shown, it is output as a half wave.
[0031]
In this way, a positive voltage half-wave output is provided to the engine control load 8 and the DC control load 3, but in this case, since the engine speed is high, each load is driven without any problem with the positive voltage half-wave output. Can do. A DC voltage smoothed by the capacitor C1 is supplied to the engine control load 8.
[0032]
In the illustrated example, the lamp 6 is driven with a negative half-wave output. For example, when the lamp is driven by a battery, a sufficient power generation voltage for the battery cannot be obtained at a low idling speed. Therefore, the lamp is mainly driven from the battery, increasing the capacity of the battery and further alternating current. The cost of the entire circuit is increased due to the increased capacity of the generator. On the other hand, by driving the lamp 6 with negative voltage half-wave output, it is not necessary to drive the lamp 6 by the battery 4, and it is not necessary to include the lighting amount of the lamp 6 in the capacity of the battery 4. The alternator 1 can also be reduced in size, and the cost of the entire circuit can be reduced.
[0033]
【The invention's effect】
Thus, according to the present invention, in a small motorcycle that kicks and starts when the battery voltage is insufficient at the time of starting, the start control circuit is electronically controlled to increase the load capacity of the second positive voltage drive load. However, it is possible to obtain double the power capacity compared to the case where only a half-wave positive voltage is supplied and to stop the driving of the negative voltage drive load without increasing the capacity of the pseudo power supply capacitor as a battery replacement. It is possible to supply sufficient electric power to the second positive voltage drive load as the engine control load even during kicking start. Therefore, since the power supply circuit can be miniaturized by using a small pseudo power supply capacitor, the layout of the apparatus can be improved and the cost can be reduced. In the normal state after starting, the output of the AC generator increases due to the high rotational speed. Therefore, even if the negative voltage drive load and the positive voltage drive load are driven by half waves, sufficient power output can be obtained. .
[0034]
In particular, when the battery voltage is insufficient at start-up, the switching element for grounding at the positive voltage when the ground terminal of the alternator is grounded at the time of positive voltage output and the negative voltage at which the voltage terminal of the alternator is grounded at the time of negative voltage output With a small element configuration by a switching element for grounding and a full-wave rectification switching element for outputting a negative voltage that is full-wave rectified at the time of negative voltage output, performing negative-wave supply stop and full-wave rectification at the start, It is possible to switch between a normal state at a high rotational speed after the start (a state in which positive and negative voltage drive loads are supplied with half waves of positive and negative voltages).
[Brief description of the drawings]
FIG. 1 is a diagram showing a power circuit of a small motorcycle to which the present invention is applied.
FIG. 2 is a time chart showing a control procedure.
FIG. 3 is an explanatory diagram showing a positive voltage waveform output state when a battery voltage shortage is detected at the start.
FIG. 4 is an explanatory diagram showing a negative voltage waveform output state when a battery voltage shortage is detected at start-up.
FIG. 5 shows a conventional power supply circuit.
FIG. 6 is a diagram showing a capacitor potential when a battery voltage is insufficient in a conventional power supply circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 AC generator 2 Battery voltage control circuit 3 DC load 4 Battery 5 Battery voltage detection circuit 6 Lamp 7 Lamp voltage detection circuit 8 Engine control load 9 Control circuit 10 Pickup coil C1 Capacitor FET1 Transistor SCR3 Thyristor SCR4 Thyristor

Claims (2)

An AC generator driven by an engine, a battery, a positive voltage drive circuit that charges the battery with a positive voltage waveform of the AC generator and drives a first positive voltage drive load, and the first positive voltage A power supply circuit for an automobile having a second positive voltage drive load connected in parallel to the drive load and performing engine control, and a negative voltage drive circuit for driving the negative voltage drive load by a negative voltage waveform of the AC generator. And
Battery state detection means for detecting the state of the battery, and full-wave rectification means for switching the output of the AC generator to full-wave rectification and supplying each positive voltage drive load,
When the battery voltage shortage is detected, the negative voltage driving circuit stops the supply of the negative voltage to the negative voltage driving load and controls to perform full wave rectification by the full wave rectifying means. A power supply circuit for an automobile, comprising a time control means. The start time control means is a positive voltage grounding switching element for grounding the alternating current generator ground terminal when the positive voltage is output, and a negative voltage grounding for grounding the alternating current generator voltage terminal when the negative voltage is output. 2. The automobile according to claim 1, further comprising: a switching element for full-wave rectification and a full-wave rectification switching element for full-wave rectifying a negative voltage when the negative voltage is output and outputting the rectified voltage to each positive voltage drive load. Power supply circuit.

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