JPH0549519U - Power supply device for vehicles with internal combustion engine - Google Patents

Abstract

(57) [Abstract] [Purpose] A power supply device for a vehicle equipped with an internal combustion engine, which reduces a possibility that the engine cannot be started due to battery exhaustion. Configuration: A main battery 1 charged by an alternator mounted on a vehicle is provided with an auxiliary battery 2 so that the main battery 1 side can be charged by a diode 4.
The output voltage V of the key switch 3 is monitored, and when it falls below a predetermined threshold value, the switching element 7 is turned on by the detection output of the comparator 6, and the relay 5 is energized to close its normally open contact 51. Electric power is supplied from the auxiliary battery 2 to the various electric component groups and the starter via the key switch 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a power supply device for a vehicle equipped with an internal combustion engine.

[0002]

[Prior Art]

 As is well known, the power source of a power supply device for an automobile equipped with an internal combustion engine is a rechargeable battery (usually a lead storage battery), and when the engine is operating, the energy generated by a generator driven by the engine is generated. In addition to driving various electrical components mounted on the vehicle, the battery is also charged, but the energy to drive the starter (cell motor) at engine start can only be obtained from the battery.

[0003]

[Problems to be solved by the device]

 For this reason, if you forget to turn off the so-called small lamps or interior lights and leave the vehicle unattended, the battery will "run up" without you knowing and the engine will not start the next time you try to ride, which is very troublesome. Sometimes. Nonetheless, there have been no conservative measures taken for this purpose, and at most, only large capacity batteries were used. In view of this point, the present invention has been made for the purpose of providing a power supply device for a vehicle equipped with an internal combustion engine, which is capable of reducing such a possibility of starting failure as much as possible.

[0004]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention usually uses a battery mounted on a vehicle as a main battery and an auxiliary battery separately from the main battery. However, this auxiliary battery is usually connected by a diode that is forward from the main battery so that it can be charged from the main battery side. Then, a comparator circuit is provided to monitor the battery voltage on the output side of the key switch and detect that the battery voltage falls below a predetermined threshold voltage value. And a battery switching circuit that short-circuits the diode and supplies power from the auxiliary battery via the key switch. Further, according to another aspect of the present invention, the comparison circuit has a second threshold value higher than the first threshold value if the predetermined threshold value is the first threshold value. After detecting that the battery voltage has dropped below the first threshold value and recovering until it exceeds the second threshold value, a second detection output is generated from the comparison circuit. Then, the battery switching circuit is operated to release the short circuit of the diode.

[0005]

【Example】

 FIG. 1 shows a circuit configuration of a main part including an embodiment of a power supply device for a vehicle equipped with an internal combustion engine, which is configured according to the present invention. In the present invention, if the battery 1 mounted on a conventional vehicle is the main battery 1, in addition to this, an auxiliary battery 2 is newly provided. The auxiliary battery 2 also needs to be a rechargeable secondary battery, but its capacity may be considerably smaller than that of the main battery 1, as will be understood from the operation described below. .

However, when the key switch (ignition switch) 3, which has a known structure, is turned to the position of the contact 31, the contact position 31 is a so-called “on position”, which is not shown in the drawing, but is not shown in the main battery. From 1 through this contact point 31, power is supplied to various electric component groups mounted on the vehicle including the ignition device. When the key switch 3 is further turned to the “start position” from this position, the output power of the main battery is supplied not only to the contact point 31 but also to the contact point 32, and the contact point 32 does not show a star (not shown). The internal combustion engine mounted on this vehicle is also started by supplying electric power to the motor (cell motor).

In the present invention, when the key switch 3 is at least turned on, that is, when the key switch 3 is attached only to the contact 31, or when the key switch 3 is attached to the contact 32 in addition to the contact 31 at the same time when the starter is started, The battery voltage V of the main battery 1 is monitored at the output side of the key switch 3. As a result, when the power supply voltage of the main battery 1 is less than or equal to the lower limit value set as the lowest allowable voltage value, the battery switching circuit is activated to supply power from the auxiliary battery 2. . As a result, when the output side voltage V of the key switch 1 recovers to a predetermined voltage value or higher, power is again supplied only from the main battery 1. The details of these operations are as follows.

The auxiliary battery 2 added by the present invention is connected so that it can be charged only from the main battery 1 side by the diode 4 which is in the forward direction when viewed from the main battery 1. Therefore, although not shown, a circuit for charging the main battery 1 may be assembled by the output of the alternator mounted on the vehicle as in the known existing circuit configuration. If the auxiliary battery 2 is in a discharging state, the auxiliary battery 2 can be charged from the output of the main battery via the diode 4 by the alternator power generation output. Of course, at this time, the normally open relay contacts 51 connected to both ends of the diode 4 in the figure remain open.

When the key switch 3 is operated and at least the output voltage of the battery 1 is applied to the contact 31, the voltage V on the contact 31 side is changed by the voltage dividing circuit of the resistors 12 and 13. The divided voltage A is applied to the negative phase input of the comparator 6. On the other hand, the electronic switch circuit formed by the resistors 14, 15 and 16 and the transistors 8 and 9 is turned on, the output voltage of the auxiliary battery 2 is clamped to a constant voltage by the Zener diode 23, and then divided by the resistors 10 and 11. The reference voltage B is applied to the positive phase input of the comparator 6.

Therefore, when the input voltage A is higher than the reference voltage B (A> B), the output of the comparator 6 maintains a low level, and in this case, the switching element 7 shown as an npn transistor is used. Since the relay 5 that is selectively driven by the switching element 7 is not energized, power is supplied from the contact point 31 of the key switch 3 to various electric component groups and from the contact point 32 to the starter. Power is also supplied only from the main battery 1. This is essentially the same as in previous vehicles.

However, when the key switch 3 is attached to the contact 31, or after that, when the key switch 3 is further rotated to the start position and attached to both the contacts 31 and 32, the output of the main battery 1 on the side of the contact 31 When the voltage A obtained by dividing the voltage V becomes lower than the reference voltage B (A <B), the output of the comparator 6 becomes high level, a base current is given through the resistors 19 and 20, and the switching element 7 is turned on. Then, the relay 5 is energized, and the normally open relay contact 51 is closed. As a result, the diode 4 is short-circuited, and power is supplied from the contact point 31 to various electric component groups including the ignition device, and power is supplied from the contact point 32 to the starter from the auxiliary battery 2.

In this way, the voltage drop of the main battery 1 is compensated, and the possibility of engine starting failure is greatly reduced. At the same time, however, the backup of the auxiliary battery 2 also results in the output voltage V of the contact 31. Will tend to recover. In the present invention, when the voltage V is restored to a predetermined value or higher, the mode is switched to the mode for supplying the electric power only from the main battery 1 again.

That is, the comparator 6 has a so-called hysteresis characteristic due to the well-known feedback resistor 18, and the reference voltage B when the comparator output is transited to the high level as described above is set to B. = B ₁ , once the output of the comparator 6 becomes high level, the reference voltage B ₂ that becomes the comparison threshold value for making the output 6 transition to low level is B ₂ > B ₁ Can be set to.

For understanding, a concrete value is given. It goes without saying that the battery voltage onboard the vehicle generally drops to the lowest level when the starter is driven. If it is possible, it can be started. Therefore, the first reference voltage B = B ₁ can be selected as 6V by converting it to the voltage V at the contact point 31 before resistance division. On the other hand, if the battery voltage tends to recover and the voltage value exceeds 9V, it is safe to rely on the power generation output of the alternator from then on, so the second reference voltage B ₂ is the same as the resistance component. It can be converted to the voltage V at the contact point 31 before pressure and selected to 9 V. In other words, the value of the feedback resistor 18 can be determined with respect to the resistance values 10 and 11 so that such a threshold value relationship is satisfied.

In this way, as shown in FIG. 2, when the voltage V at the contact point 31 has reached a nominal value of 12V, actually more than 13V, it begins to decrease and falls below 6V. A comparison circuit including the above-mentioned comparator 6 detects a drop in the main battery voltage, operates the relay 5 to close the normally open contact 51, and power is supplied from the auxiliary battery 2. As a result, if the voltage V of the contact 31 tends to rise and eventually exceeds 9 V, the comparison circuit including the comparator 6 turns off the switching element 7 to normally excite the relay 5 when the relay 5 is excited. Since the contact 51 is returned to the steady position, the power supply to the various electric component groups via the contact 31 is again performed only from the main battery 1, and the auxiliary battery 2 is conversely charged via the diode 4 in a chargeable state. Become. As is apparent, in this embodiment, the resistors 10 to 13, the resistor 18, and the comparator 6 form a comparison circuit, and the switching element 7, the relay 5, and the normally open contact 51 form a battery switching circuit. .

However, the hysteresis characteristic as shown in FIG. 2 is a desirable structure, and if only the most basic aspect of the present invention is satisfied, the comparator 6 has a hysteresis characteristic. It is not essential that the first and second threshold values B ₁ and B ₂ described above are equal to each other.

As is apparent, the electronic switch circuit composed of the resistors 14, 15, 16 and the transistors 8, 9 causes the comparator circuit to be powered and turned off only when the key switch 1 is turned on. It is provided to prevent wasteful power consumption from the auxiliary battery 2 when it is in the position. Therefore, in the figure, the power source of the comparator 6 is taken out from the voltage line clamped to a constant voltage by the Zener diode 23.

Of course, the switching element 7 and the like can also be designed by using another semiconductor switching element instead of the illustrated bipolar transistor. And, as is apparent from the above operation, the capacity of the auxiliary battery is sufficient if it can supply a large amount of electric power for a relatively short time in an emergency, and it can be placed in a rechargeable state rather than being normally used. Therefore, a sufficiently small battery is sufficient as compared with the main battery 1. There is ample room for installation even in the existing vehicle space. Further, the capacitors 21 and 22 are for smoothing to stabilize the voltage values A and B against fluctuations in the power supply voltage.

[0019]

[Effect of the device]

 According to the present invention, even when the voltage of the main battery drops and it is not possible to drive the starter by itself, backup from the auxiliary battery can be performed, and the lamps of the vehicle have been forgotten. Therefore, the inconvenience that the engine cannot be started can be reduced. Further, when the battery voltage is restored, the auxiliary battery can be automatically returned to the chargeable state, so that both the main battery and the auxiliary battery can last a long time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part including an embodiment of a power supply device configured according to the present invention.

FIG. 2 is an explanation regarding the operation of the power supply device shown in FIG.

[Explanation of symbols]

 1 main battery, 2 auxiliary battery, 3 key switch, 4 diode, 5 relay, 6 comparator, 7 switching element, 8 switching element, 9 switching element, 23 Zener diode, 31 key switch on contact, 32 key switch start Contact, 51 normally open relay contact, V battery voltage, A battery partial voltage, B reference voltage.

Claims (3)

[Scope of utility model registration request] 1. An electric component group mounted on a vehicle is supplied with electric power through an ON position of a key switch, and a starter is also supplied with electric power through a start position while being driven by an internal combustion engine started by the starter. A power supply device for a vehicle equipped with an internal combustion engine, comprising a battery that can be charged with the power generation output of an alternator; the battery as a main battery; an auxiliary battery provided in addition to the main battery; While being connected so as to be rechargeable via a diode that is in the forward direction when viewed from above, the battery voltage is monitored at the output side of the key switch, and it is detected that the voltage is below a predetermined threshold voltage value. A comparison circuit,
A battery switching circuit that short-circuits the diode based on the output of the comparison circuit and supplies the power from the auxiliary battery through the key switch;
A power supply device for a vehicle equipped with an internal combustion engine. 2. The power supply device according to claim 1, wherein the comparison circuit uses the predetermined threshold value as a first threshold value, and the second threshold value is higher than the first threshold value. A second threshold output is detected when the battery voltage exceeds the second threshold value after detecting that the battery voltage is below the first threshold value; The battery switching circuit, by the second detection output from the comparison circuit,
A power supply device characterized by releasing a short circuit of the diode. 3. The power supply device according to claim 1, wherein an electronic device that supplies operating power to the comparison circuit and the battery switching circuit only when a battery voltage appears on the output side of the key switch. A power supply device having a switch circuit;