JP3228484B2 - Poor contact prevention system for vehicle power relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for preventing a contact failure of a power supply relay for a vehicle, which prevents a contact failure due to a contamination film formed on a relay contact.

[0002]

2. Description of the Related Art In general, many vehicles such as automobiles supply power from a battery to each electric load via a power supply relay which is opened and closed in conjunction with an ignition switch. By installing it, the ignition switch in the vehicle compartment opens and closes a relatively small current, shortens the wiring length from the battery to the load via the power supply relay, and suppresses voltage drop and heat generation due to the increase in wiring length. I have.

[0003] In this case, if a contact failure occurs in the relay contact of the power supply relay, a specified voltage is not supplied to each electric load, which causes a malfunction of the device.
Japanese Patent Application Laid-Open No. 607575 discloses that when a voltage applied to electrical components via a relay is lower than a set value, the relay is temporarily turned off.
There is disclosed a technique for preventing a contact failure by releasing an unconductor (foreign matter) caught in a relay contact by performing an F operation.

[0004]

However, the cause of the contact failure of the relay contact is, in addition to the foreign matter biting,
There is a contaminant film formed on the contact surface. For example, in the engine room of a car, heat containing silicon compounds,
Many rubber products for waterproofing and various plastic products are used. The silicon compound (silicon gas) released by exposure to high temperature atmosphere is changed to silicon oxide by arc discharge etc. between the relay contacts, and it becomes on the contact surface. Adhesion forms a contamination film on the contact surface.

In this case, the generated contaminating film is strong and cannot be removed only by temporarily turning off the relay as in the above-mentioned prior art. Will occur.

The present invention has been made in view of the above circumstances, and it is possible to destroy a contamination film formed on a relay contact of a power supply relay for supplying power to each electric load of a vehicle, thereby preventing contact failure of the contact. It is an object of the present invention to provide a system for preventing poor contact of a power relay for a vehicle.

[0007]

Means for Solving the Problems To achieve the above object,
Therefore, the present invention provides a power supply
Apply a current that is large enough to break the fouling film for a set time, and
Of the power relay by destroying the stain film formed on the
Contact failure prevention system for vehicle power relay to prevent poor contact
System after the ignition switch is turned off.
During the fixed time, the current flows through the relay coil of the power supply relay,
Equipped with an electronic control unit that holds the power supply
Place each actuator on the electrical load side of the relay contact.
Actuator in the drive circuit of the electronic control device via
Data drive power transistors connected in parallel
Each actuator can be controlled by an electronic control unit,
Further, the drive circuit of the electronic control unit has another power drive.
The power relay is equipped with a transistor.
On the load side, connect the relay connection
Through a resistor to allow a large current less than the maximum
Connect the other power transistors in the above drive circuit
The electronic control unit operates when the ignition switch is turned on.
When the engine is in operation,
Switch off to de-energize the resistor, and turn on the ignition switch.
When the switch is turned off, each of the actuator drive
Turn off the power transistor and supply power to each actuator.
And disconnect the other power transformers for the set time.
Turn on the transistor to allow the maximum
Apply a large current less than the capacity current, and then turn off the power relay
It is characterized by shutting off the power holding.

[0008]

According to the present invention , after the ignition switch is turned off,
The current to the relay coil of the power relay for the set time.
It has an electronic control unit that allows the power to flow and self-holds the power. Soshi
Each on the electrical load side of the relay contact of the power relay.
In the drive circuit of the electronic control unit via the actuator
Parallel power transistors for driving the actuator
Each actuator can be controlled by an electronic control unit when connected
Noh. Furthermore, the drive circuit of the electronic control unit has other parameters.
Power transistor and the power of the relay contact of the power relay.
In parallel with each actuator on the air load side,
Drives via a resistor to allow a large current less than the maximum allowable current to flow
Connect other power transistors in the circuit. And
The child control unit has an engine with the ignition switch on.
Turn off other power transistors when
The resistor is de-energized. And the ignition switch
When is turned off, the electronic control unit
Turn off each power transistor to activate each actuator
Disconnect the power supply from the power supply and
-Turn on the transistor and connect it to the relay contact of the power relay.
Apply a large current less than the maximum allowable current and generate it at the relay contact.
After breaking the fouling film, turn off the power relay and hold the power
Cut off.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a flowchart showing a power supply relay control routine, and FIG. 2 is a circuit diagram of an electronic control system.

In FIG. 2, reference numeral 1 denotes an electronic control unit (EC) for performing vehicle control such as fuel injection control and ignition timing control.
U), and the ECU 1 includes a microcomputer 2
Is composed of an input interface (I / F) 3, an analog / digital converter (ADC) 4, an output interface (O / F) 5, a drive circuit 6, a constant voltage circuit 7, and the like.

The I / F 3 includes an intake air amount sensor 8,
Intake pipe pressure sensor 9, water temperature sensor 10, O2 sensor 1
1, various sensors such as a crank angle sensor 12, various switches such as an idle switch 13 and an ignition switch 14, and a plus terminal side of a battery 15 are connected, and amplification, waveform shaping, and noise removal processing of each signal are performed. Perform

The ADC 4 converts an analog signal processed by the I / F 3 into a digital signal at a predetermined timing according to a control signal from the microcomputer 2 and outputs the digital signal to the microcomputer 2.

The microcomputer 2 includes, for example,
A single-chip microcomputer in which a CPU, a ROM, a RAM, a timer, and the like are integrated on a single LSI chip. According to a control program stored in the microcomputer, the ADC 4 converts the signals of sensors into digital signals and the like. A control amount such as a fuel injection amount, an ignition timing, and an idle speed is calculated based on an engine operating state based on a signal of each switch processed by the I / F3, and a corresponding signal is output from an output port.

The O / F 5 generates an input signal to the drive circuit 6 for the microcomputer 2 having a small load driving capability based on a signal output from an output port thereof. The driving circuit 6 includes NPN-type power transistor groups T1,..., Ti,.
It consists of a P-type power transistor TS, and the base of each power transistor is connected to the output terminal of the O / F5.

The above-mentioned NPN type power transistor group T1,
, Ti,..., Tn and TR have their emitters grounded, and actuators such as an injector 16 and an idle speed control valve (ISCV) 17 connected to the collectors of the power transistors T1,..., Ti,. To the collector of the power transistor TR, a resistor 20 having a low resistance value for flowing a large current less than the maximum allowable current to the relay contact is connected to prevent a contact contact failure of the power supply relay 19 described later.

The PNP power transistor T
S has a constant voltage VC supplied from the constant voltage circuit 7 to the emitter, and a collector connected to the battery 15 via the ignition switch 14 via the ignition switch 14.
Diode 18 and power supply relay 1 in the forward direction with respect to the positive electrode of
9 and is connected to a connection point with the relay coil 19c, and according to the output port value GS from the microcomputer 2,
Even after the ignition switch 14 is turned off, a current is applied to the relay coil 19c to turn on the power supply relay 19.
Then, the power supply to the ECU 1 is held, and when a set time has elapsed, the current to the relay coil 19c is cut off to turn off the power supply relay 19, thereby realizing a self-shut function of automatically cutting off the power supply to the ECU 1. It has become.

On the other hand, the power supply relay 19 is connected to the ECU
Relay contact 19a used to supply power to
And two normally open contacts, a relay contact 19b used for supplying power to each electric load mounted on the vehicle, and the other end of the relay coil 19c is grounded.

The constant voltage circuit 7 is connected to the battery 15 via one relay contact 19a, and a battery voltage (for example, 12 V) supplied from the battery 15 is supplied.
V) is stabilized to a predetermined level of a constant voltage VC (for example, 5 V) and supplied to each unit in the ECU 1. further,
The injector 1 is connected via the other relay contact 19b.
6. A power supply terminal of each actuator such as the ISCV 17 and one end of the resistor 20 are connected to the battery 15.

Here, the power supply relay 19 has a value in which a current flowing through each contact in a steady state has a sufficient value with respect to the maximum allowable current, and is installed in an engine room (not shown). In the engine room, various components containing silicon compounds are attached in many respects from the viewpoint of heat resistance and waterproofness. Since silicon compounds are released from these components in a high-temperature atmosphere, each component of the power supply relay 19 is provided. A contamination film may be formed on the relay contacts 19a and 19b.

In general, it is known that there is a correlation between the occurrence of a contact failure due to a contamination film on a contact and the type of a connected load, a current value, a switching voltage value, environmental conditions, and the like. When the current and the voltage have intermediate values, there is a high possibility that a contact failure occurs most. Therefore, in the power supply relay 19, the relay contact 19a having a relatively small current is used.
Therefore, even in the above-described environment in the engine room, a contamination film having a large thickness that causes poor contact is hardly generated, and
The constant voltage circuit 7 to which the relay contact 19a is connected
Has a relatively wide allowable input range, so that even if a thin contaminant film is formed, the effect of the film resistance can be ignored.

On the other hand, in the relay contact 19b of the power supply relay 19, the current and voltage values are in an area where contact failure is likely to occur, and the connected loads are often inductive, so that arcing is not possible. Discharge occurs. This arc discharge does not have enough energy to destroy a thick contaminated film. Conversely, the silicon compound liberated in the engine room changes into silicon oxide (SiO2) between the contacts, and the surface of the relay contact 19b A strong contaminant film is formed. For this reason, in the relay contact 19b, there is a high possibility that a contact contact failure occurs.

Therefore, in the ECU 1, when the ignition switch 14 is turned off, the power relay 1
By flowing a large current through the relay contact 19b for a set time, the contamination film is destroyed, and contact failure of the contact is prevented. Hereinafter, this operation will be described with reference to the flowchart of the power supply relay control routine of FIG.

This power supply relay control routine is executed by the ECU 1
The program is executed every predetermined time while the power is turned on. First, in step S101, it is determined whether or not the ignition switch 14 is OFF.

When the ignition switch 14 is
N, when the engine is operating, the process proceeds from step S101 to step S102, where the output port value GR of the microcomputer 2 with respect to the resistor 20 is set to 0 (GR ← 0), and the power transistor TR of the drive circuit 6 is set to O.
As the FF, the state is cut off so that no current flows from the battery 15 to the resistor 20 via the relay contact 19b of the power supply relay 19, and the process proceeds to step S103.

In step S103, when the count value C1 for measuring the elapsed time after the ignition switch 14 is turned off is cleared (C1 ← 0), step S1 is performed.
Proceeding to 10, the output port value GS of the microcomputer 2 for the power supply relay 19 is set to 0 (GS ← 0), and the routine exits. Thereby, when the ignition switch 14 is turned off, the power transistor T
S is turned on to supply the constant voltage VC to the relay coil 19c of the power supply relay 19.

When the ignition switch 14 is turned off to stop the engine, a constant voltage VC is applied to the relay coil 19c of the power supply relay 19 by the power transistor TS of the drive circuit 6, and the power supply relay 19
Is held, and the ECU 1 keeps the operating state.

Generally, the self-holding voltage that can hold the ON state after the relay is operated from OFF to ON is:
The constant voltage VC is sufficiently lower than the rated voltage of the relay.
Although the voltage value is lower than the battery voltage, the voltage value has a sufficient margin for the self-holding voltage of the power supply relay 19.

Then, the power supply relay control routine is started again, and in step S101, the ignition switch 1 is turned on.
When it is determined that No. 4 is OFF and the process proceeds to step S104, the output port values G1,..., Gi,.
Is set to 0 to disconnect each load from the battery power supply.

Next, the process proceeds to step S105, where the output port value GR of the microcomputer 2 for the resistor 20 is set to 1
Then, the power transistor TR of the drive circuit 6 to which the resistor 20 is connected is turned on. As a result, a large current less than the maximum allowable current flows from the battery 15 through the relay contact 19b of the power supply relay 19 to the resistor 20.

Next, in step S106, the count value C1 is counted up (C ← C + 1), and step S107 is performed.
Then, the count value C is compared with the first set value CS1, and it is determined whether or not a set time has elapsed since a large current was supplied to the relay contact 19b.

As a result, if C1 <CS1, and the set time has not elapsed, the routine exits from the above-described step S107 through the above-described step S110. If C1 ≧ CS1, and the set time has elapsed, Step S1 above
From step 07, the process proceeds to step S108, in which the output port value GR of the microcomputer 2 for the resistor 20 is set to 0, the power transistor TR of the drive circuit 6 is turned off, and the current flowing from the battery 15 through the relay contact 19b of the power supply relay 19 is cut off. I do.

That is, when the ignition switch 14 is turned off, each electric load is disconnected from the battery power supply, and a large current of less than the maximum allowable current flows through the relay contact 19b of the power supply relay 19 for a set time.
Therefore, when the ignition switch 14 is turned on and the engine is started, malfunction of the equipment can be avoided beforehand.

Thereafter, the steps S108 to S1 are performed.
09, the count value C1 is changed to the second set value CS2 (however,
(CS1 <CS2) to determine whether or not a set time has elapsed since the ignition switch 14 was turned off.
If C1 <CS2, and the set time has not elapsed, the routine exits from the step S109 through the above-described step S110. If C1 ≧ CS2, and the set time has elapsed, the steps S109 to S111 Then, the output port value GS of the microcomputer 2 with respect to the relay coil 19c of the power supply relay 19 is set to 1 and the power transistor TS is turned off, thereby turning off the power supply relay 19.
Is set to OFF. As a result, the power supply of the ECU 1 is cut off, and the operation of the ECU 1 is stopped.

[0034]

According to the present invention as described above, according to the present invention, i
After turning off the ignition switch, the power
Apply current to the relay coil of the relay to hold the power supply
Electronic control device. And the relay of the power relay
Each actuator on the electrical load side of the contact
For driving actuators in drive circuits of electronic control units
Power transistors in parallel to create an electronic control unit
Each actuator can be controlled more. Furthermore, electronic
The drive circuit of the control device has other power transistors.
Each actuator on the electrical load side of the relay contact of the power supply relay.
Large current of less than the maximum allowable current
Other power transformers via a resistor for flowing the current
Connect the transistor. And the electronic control unit
When the engine switch is on and the
Turn off the power transistor and de-energize the resistor
When the engine is in operation, a large current is not
In addition to preventing power flow, eliminating power waste
Malfunction of each actuator due to drop in power supply voltage, etc.
Can be eliminated and control reliability can be significantly improved.
You. And the electronic control unit is an ignition switch
When the power is turned off, the power
Turn off the transistor and disconnect each actuator from the power supply.
As well as disconnect other power transistors for the set time.
Turn on the power relay relay contact below the maximum allowable current
High current to destroy the fouling film formed on the relay contacts
After that, turn off the power relay and cut off the power holding,
Engine completely independent of malfunction of each actuator
Immediately after shifting to stop, the maximum
A large current less than the allowable current flows, and the relay contact of the power relay
It is possible to surely destroy the contaminated film adhered to the surface. You
That is, the engine is turned off when the ignition switch is turned off.
Is stopped, and each actuator is
With the power supply completely shut off,
-It is possible to flow a large current less than the maximum allowable current to the contact
To prevent malfunction of the actuator
Poor contact of power relay without adversely affecting control
Can be reliably prevented, and the reliability can be significantly improved.
You. Also, when the engine is running with the ignition switch on.
The ignition switch is turned off from the
Each time the power supply is stopped, the
Strong soiled film grows as damaged soiled film is destroyed
Contact of the relay contacts
Eliminating defects can further improve reliability
You. Then, each actuator and the above-mentioned resistance
After making sure that the load is disconnected from the power supply,
Turn off the power relay and cut off the power holding.
It is possible to eliminate waste of power due to air load and the electronic control device.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a power supply relay control routine.

FIG. 2 is a circuit diagram of an electronic control system.

[Explanation of symbols]

 14 Ignition switch 19 Power supply relay 19b Relay contact CS1 set time

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60R 16/02 650

Claims (1)

(57) [Claims] (1) The relay contact of the power supply relay has a stain on the contact surface.
A current large enough to destroy the damaged film
ー Destroys the fouling film formed on the contacts and contacts the power relay.
Contact failure prevention system for vehicle power relay to prevent failure
Power on for a set time after the ignition switch is turned off.
Supply current to the relay coil of the power supply relay to hold the power supply
Electronic control devices, each of which is located on the electrical load side of the relay contact of the power supply relay.
In the drive circuit of the electronic control unit via the tutor
Parallel power transistors for driving the actuator
Connected and each actuator is controlled by the electronic control unit.
And the drive circuit of the electronic control unit has another power source.
The power relay is equipped with a transistor.
On the load side, connect the relay connection
Through a resistor to allow a large current less than the maximum
Connected to another power transistor of the drive circuit, and the electronic control unit turns on the ignition switch.
When the engine is running, the other power transistors
Switch off to de-energize the above resistor and turn on the ignition switch.
When the switch is turned off, the actuator drive
Turn off the power transistor and power each actuator
From the other power sources for the set time.
Turn on the transistor and apply the maximum
Apply a large current less than the allowable current, and then turn off the power relay.
A contact failure prevention system for a vehicle power relay characterized by shutting off the power supply .