JPH0672263A - Power source circuit of vehicle - Google Patents

Abstract

PURPOSE:To improve the cutting-off property, the durability, and the like by preventing the generation of an arc discharge of a relay contact when a power source is cut off, in a power source circuit using an ignition switch and an ignition relay. CONSTITUTION:A battery 1 is connected to the coil 3b of an ignition relay 3 through a first switch means 11, while it is connected to a second switch means 12 through the contact 3a of the ignition relay 3 and a load 5. And when an ignition switch 2 is OFF, in particular, the second switch means 12 is turned OFF at first so as to cut off electrically the load 5 or the like which has an indactance, by an ON/OFF detecting means 10, and after a specific time passes, the first switch means 11 is turned OFF, and the ignition relay 3 is turned OFF to prevent the generation of an arc discharge of the ignition relay 3, so as to cut off the power source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for supplying or cutting off a battery power supply to or from a load in a vehicle by an ignition switch or an ignition relay.
Specifically, it relates to measures for preventing contact failure of the ignition relay when the power is cut off.

[0002]

2. Description of the Related Art Generally, in a power supply circuit of a vehicle, a battery is connected to an ignition switch through a coil of an ignition relay, and at the same time, connected to loads such as various control valves and indicators via contacts of the ignition relay. . The coil of the ignition relay is energized or de-energized by turning on / off the ignition switch to turn its contact on or off to supply or cut off the power supply voltage.

According to this structure, when the power is cut off, the coil is de-energized with the contact of the ignition relay turned on, that is, with the power source and the load connected. Therefore, if the load has an inductance, a reverse current flows when the coil is de-excited, causing arc discharge due to back electromotive force at the contacts, resulting in contact failure of the contacts and loss of relay durability. U Therefore, it is desired to configure and control the power supply circuit so that such a back electromotive force is not generated when the power is shut off.

Conventionally, regarding the power supply circuit of the vehicle, there is a prior art disclosed in, for example, JP-A-64-60757.
Here, as a countermeasure when the non-conductor is caught in the relay contact, the voltage applied to the electrical component is detected with the ignition switch turned on, and if the voltage is below the set value, the relay is temporarily turned off. It is shown to be turned off to remove the non-conductor.

[0005]

By the way, in the above-mentioned prior art, since the battery is connected to the contact of the ignition relay and at the same time connected to the ignition switch and the coil of the ignition relay, When the ignition relay is turned off, arc discharge may occur at the contact, resulting in poor contact.

The present invention has been made in view of this point, and in a power supply circuit using an ignition switch and an ignition relay, arc discharge of a relay contact at the time of power-off is prevented to improve cutting performance and durability. The purpose is to do.

[0007]

In order to achieve the above object, the present invention connects a battery to a coil of an ignition relay via a first switch means, and at the same time, connects a contact of the ignition relay to a second side via a load. The ON / OFF detecting means for detecting ON / OFF of the ignition switch outputs the signal when the ignition switch is ON to both switch means at the same time, and the signal when the ignition switch is OFF is In addition to outputting to the second switch means, it is also configured to output to the first switch means after a predetermined delay time has elapsed.

[0008]

According to the above construction, when the ignition switch is turned on, the first switch means is turned on by the ON / OFF detection means and the ignition relay is also turned on, and at the same time, the contact side of the ignition relay is connected by the second switch means. Battery power is supplied to the control unit and the load. Also, when the ignition switch is off, O
First, the second switch means is turned off by the N / OFF detection means.
The load and the like having an inductance are electrically disconnected by FF, and thereafter, the ignition relay is turned off without the occurrence of back electromotive force or arc discharge due to the inductance of the load when the first switch means is turned off.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The configuration of the power supply circuit of the vehicle will be described with reference to FIG. Reference numeral 1 is a battery, and the battery 1 is connected to an ignition switch 2 and a contact 3a of an ignition relay 3. The ignition switch 2 is connected with ON / OFF detecting means 10 for detecting ON and OFF thereof, and the coil 3b of the ignition relay 3 is connected with the battery 1 through the switch means 11. Further, the contact 3a of the ignition relay 3 is connected to another switch means 12 via a load 5 having an inductance of each control valve or the like. In addition, 13 is a timer. The ON / OFF detecting means 10, the switching means 11 and 12, and the timer 13 are integrated as a control unit 4, and the switching means 11 and 12 use electronic elements such as transistors.

When the ON / OFF detecting means 10 detects that the ignition switch 2 is ON, the ON / OFF detecting means 10 outputs an ON signal to the switch means 11 to output the coil 3b of the ignition relay 3.
Is excited, the contact 3a side is connected, and the ignition relay 3 is turned on. On the other hand, the ignition switch 2 is turned on.
The signal is ready to be output to the switch means 12 to receive power from the battery 1, the control unit 4 and the load 5.
Supply power to. Also, the ignition switch 2 O
When the FF is detected, the OFF signal is first sent to the switch means 12
To load 5 is released. Further, at this time, an OFF signal is output to the timer 13, the switch means 11 is turned off after a predetermined delay time T has elapsed, the coil 3b of the ignition relay 3 is de-energized, and the ignition relay 3 is turned off. . In this case, the delay time T of the timer 13 is set according to the magnitude of the inductance of the load 5.

Next, the operation of this embodiment will be described. First, when the engine starts, the ignition switch 2
When turned on, the ON / OFF detection means 10 simultaneously outputs an ON signal to the two switch means 11 and 12
N Therefore, the ignition relay 3 is turned on by contacting the contact 3a when the coil 3b is excited by the power source of the battery 1, whereby the power source of the battery 1 is switched.
It is supplied to the control unit 4 and the load 5 via 2, so that various controls and operations are performed.

A case in which the ignition switch 2 is turned off when the engine is stopped will be described with reference to the flowchart of FIG. First, when it is checked that the ignition switch 2 is OFF in step S1, the process proceeds to step S2. That is, O from the ON / OFF detection means 10
The FF signal is immediately output to the switch means 12 and turned off.
Then, the load 5 having the inductance is disconnected from the ground contact. At this time, since the contact 3a is connected, the arc discharge based on the counter electromotive force due to the inductance of the load 5 does not occur.

Thereafter, the process proceeds to step S3, the count value C of the timer 13 is set, and the count value C is set at step S4.
And the delay time T are compared. When the count value C becomes larger, an OFF signal is output to the switch means 11 to turn it off in step S5. Therefore, at this time, the coil 3b of the ignition relay 3 is de-excited, and the contact 3a thereof is separated and turned off. At this time, the load 5 having the inductance is already electrically disconnected, so that the contact 3a side of the ignition relay 3 is connected to the coil 3
In the case of non-excitation of b, the back electromotive force and the arc discharge accompanying it will not occur. After that, in step S6, the count value C of the timer 13 is cleared and the process ends.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto.

[0015]

As described above, according to the present invention,
In a vehicle power supply circuit that uses an ignition switch or an ignition relay, when the ignition switch is turned off, a load having an inductance or the like is electrically released in advance before turning off the ignition relay. Generates a much smaller back electromotive force than the conventional method even when the power supply voltage is applied to the. Therefore,
It is possible to reliably prevent the occurrence of arc discharge when the ignition relay is turned off. Therefore, the contact failure of the ignition relay is eliminated, and the durability of the contact is improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a power supply circuit for a vehicle according to the present invention.

FIG. 2 is a flow chart showing control when the ignition switch is OFF.

[Explanation of symbols]

 1 Battery 2 Ignition Switch 3 Ignition Relay 3a Contact 3b Coil 4 Control Unit 5 Load 10 ON / OFF Detection Means 11, 12 Switch Means 13 Timer

Claims (2)

[Claims] 1. A battery is connected to a coil of an ignition relay via a first switch means, and at the same time, a contact of the ignition relay is connected to a second switch means via a load to detect ON / OFF of the ignition switch. A signal from the ON / OFF detection means when the ignition switch is ON is simultaneously output to both switch means, and a signal when the ignition switch is OFF is output to the second switch means, and a predetermined delay time has elapsed. A power supply circuit for a vehicle, wherein the power supply circuit is configured to output to the first switch means after the operation. 2. The power supply circuit for a vehicle according to claim 1, wherein the delay time is set by a timer based on the magnitude of the load and its inductance.