JPH06260215A - Battery charger for automobile battery - Google Patents

Abstract

PURPOSE:To perform appropriate charging to which the temperature of a battery is added, by connecting a battery temperature detecting element so that one end of which is in common to the voltage detecting point within a regulator so as to be in parallel to a voltage dividing resistor on the high potential side, and so that the other end of which is connected to + terminal of a battery. CONSTITUTION:A Zener diode Zb as a battery temperature detecting element is connected so that one end of which is in common to a voltage detecting point (a) within a regulator 22 in parallel to a voltage dividing resistor Rv on the high potential side. In that case, since the other end of the Zener diode Zb is connected to + terminal of a battery 25, the temperature of a battery is accurately transmitted through a pole and a voltage is dropped with the rising of the temperature. Therefore, the combined resistance of the resistor Rv and the Zener diode Zb is lowered, the potential at the point (a) is increased, and when the potential exceeds the voltage of a Zener diode Dz, a transistor(Tr) 1 is turned on, and a power transistor(Tr) 24 comes toward the state of being turned off. Thereby, the field current of an alternator 22 is reduced to prevent overcharge, so that appropriate charging may be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device for an automobile storage battery.

[0002]

2. Description of the Related Art Recently, there has been a remarkable increase in performance and specifications of automobiles. For example, even if the same car model was used 10 years ago,
The displacement of 500 to 2000 CC is now 2000 to 3000 CC. In addition, air conditioning equipment and power steering, which were once optional equipment, are now standard equipment. As a result, various equipment is densely packed in the bonnet, and in the past, the location of the storage battery was decided to be the front part of the bonnet,
Today, it is right next to the engine, or at the deepest part of the hood. In such a state, the ventilation in the bonnet is extremely deteriorated, and the storage battery temperature may be as high as never thought in the past. It is well known that storage batteries are adversely affected when exposed to high temperatures. A lead acid battery uses sulfuric acid as an electrolytic solution, but at high temperatures, its oxidizing power becomes remarkably strong, and the electrode plate active material, the grid and the like are corroded, resulting in a short life. Therefore, in order to keep the environment as low temperature as possible, a heat-resistant cover is provided around the storage battery, but if it is left in the idling state for a long time or in the low driving mode state due to traffic congestion, the storage battery temperature will be unavoidable. To rise. In the case of lead-acid batteries, the charging voltage is 3 m
V / ° C decreases. For this reason, the alternator of the car
Charge regulation that takes temperature into consideration is adopted. This regulation is set in the range of -10 ° C to 60 ° C so that the storage battery is charged without excess or deficiency.

[0003]

However, there is a problem that the temperature detection point of the temperature detection sensor incorporated in the alternator and the battery temperature are significantly different. This is because a large difference occurs in the temperature rising tendency due to the difference in specific heat between the storage battery and the alternator. For example, during idling, the temperature of the alternator rises by as much as about 50 ° C. in 30 minutes, whereas that of the storage battery only rises by about 10 ° C. A similar tendency appears when the temperature is further lowered. For example,
When there is a difference of 50 ° C. from the outer peripheral temperature, the storage battery drops only about 10 ° C. in 30 minutes, while the alternator also drops by 40 ° C., and the storage battery temperature and the alternator temperature differ by as much as 30 ° C. When charged in such a state, the storage battery receives a large overcharge. The charging voltage of the storage battery tends to decrease with age. this is,
This is because the antimony eluted from the antimony alloy lattice of the + electrode plate is deposited on the − electrode plate and the charging voltage is lowered. This antimony is likely to elute especially when overcharged. A storage battery at the end of its life is 2V / 6 compared to a storage battery in a normal state.
It may even drop by more than a cell. As described above, maintaining the charge control of the storage battery in the optimum state is affected by many factors such as the temperature condition and the deterioration condition of the storage battery, which is very difficult.

The present invention has been made to solve the above problems, and an object thereof is to provide a charging device for an automobile storage battery capable of performing more appropriate charging.

[0005]

In view of the above, the present invention is connected in parallel to a voltage dividing resistor on the higher potential side of a voltage detection point in a regulator, one end of which is a + terminal of a storage battery and the other end of which is a regulator. The above problem is solved by providing a battery charger for an automobile storage battery, which comprises storage battery temperature detection elements respectively connected to the internal voltage detection points.

[0006]

EXAMPLES The present invention will be described in detail below with reference to specific examples. FIG. 1 is a circuit diagram showing a charging device for an automobile storage battery according to an embodiment of the present invention. The alternator 21 incorporates a regulator 22, and the regulator 22 controls the field current to adjust the output voltage. Point a in the regulator 22 is a voltage detection point, and this voltage value is determined by the voltage dividing resistors Rv and R1. Assuming that the storage battery voltage during charging is VB, the voltage at point a is (VB x R1) /
(Rv + R1). Dividing resistor Rv is on the high potential side, R1
Is the low potential side. When the charging voltage rises, the voltage at the point a rises, and when this voltage becomes higher than the voltage of the Zener diode Dz, the transistor Tr1 is turned on, and the collector voltage of the transistor Tr1 is lowered, and the power transistor 24 is turned off. Therefore, the potential of the collector terminal F increases and the field current decreases. As a result, the potential of the output terminal B of the alternator 22 drops and the charging voltage drops.

In a normal regulator, the Zener diode Dz serves as a temperature detecting element. Since the Zener voltage decreases as the temperature rises, the output power of the alternator is configured to decrease, and the temperature gradient of the regulator is determined by the Zener diode Dz. Since the Zener diode Dz is a small electronic component, it has almost no heat capacity and its temperature change follows the temperature change of the alternator. As mentioned above, the specific heat of the alternator is about 1/5, which is smaller than that of the storage battery. Therefore, the temperature of Dz is often higher during idling, and conversely, the temperature of the storage battery is higher during traveling. In the worst case, the temperature difference between the two is 3
It may be 0 to 50 ° C. Zener diode D
If z is pulled out from the regulator and brought into close contact with the storage battery, accurate temperature detection can be performed, but should the lead wire be disconnected, the transistor will turn off and the F terminal will become OV.
The maximum amount of field current flows, causing not only overcharge of the storage battery but also damage to the vehicle load.

The present invention prevents this by connecting the Zener diode ZB in parallel with the dividing resistor Rv for detecting the temperature of the storage battery. Zener diode Z
Since B is connected to the + terminal of the storage battery, its temperature is accurately transmitted to the Zener diode ZB through the storage battery pole. Zener diode Z due to temperature rise of storage battery
When the temperature of B rises, the voltage of the Zener diode ZB drops and the combined resistance of the resistor R and the Zener diode ZB drops. As a result, the voltage at point a rises, the output voltage of the alternator drops, and overcharge of the storage battery is prevented. The resistor RB in the figure is the resistor Rv and the Zener diode.
It is an adjustment resistor to make the composition with the de ZB a predetermined value,
This is to prevent a short circuit accident even if the plug is disconnected and grounded to the vehicle body. A diode D is inserted between point a and a'on the regulator 22 side. This is to prevent the storage battery from being damaged when the sensor line is grounded at any part of the vehicle body, the detection voltage point a becomes OV, and the output of the alternator 21 rises to the maximum voltage. Therefore, even if some failure occurs in the battery charger for the automobile storage battery, the regulator 22 cannot detect the temperature of the storage battery, but the temperature regulation remains. It will not drop abnormally and discharge the storage battery. In this embodiment, the Zener diode is used as the storage battery temperature detecting element, but another thermistor may be used.

Since the sensor portion consisting of the Zener diode ZB and the resistor RB lacks in strength, it may be fixed by welding to the storage battery + terminal connecting plate and molded with resin. By doing so, it is possible to prevent the element from being damaged by the electrolytic solution scattered from the storage battery.

[0010]

According to the charging device for an automobile storage battery of the present invention, it is possible to change the regulation taking into consideration the actual storage temperature of the storage battery while maintaining the existing charging regulation characteristic, and to perform better charging. . Also,
Since the sensor unit having the temperature detecting element is small, it can be integrally fixed to the + terminal of the storage battery, and since only one sensor line is required, wiring is easy. Further, even if a disconnection of the sensor wire or the like occurs, the output characteristic of the existing alternator can be secured at the minimum, so that the reliability is high.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an automobile storage battery charging device that is an embodiment of the present invention.

[Explanation of symbols]

 21 Alternator 22 Regulator 24 Power Transistor 25 Storage Battery Rv Resistor ZB Zener Diode

Claims (1)

[Claims] 1. A regulator (22) is connected in parallel to a voltage dividing resistor (Rv) on the higher potential side of a voltage detection point (a), one end of which is connected to a + terminal of a storage battery (25) and the other end of which is connected. Are connected to the voltage detection points (a) in the regulator (22) and are connected to the storage battery temperature detection elements (Z
B), a battery charger for an automobile battery.