JPH111155A - Switch state detection device for vehicles - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To reduce the power consumption of a battery when an on-vehicle switch is closed when an engine is stopped, and to open / close the on-vehicle switch without being affected by an oxide film formed on a contact point of the on-vehicle switch. An apparatus capable of detecting a state is provided. SOLUTION: Power is always supplied to a key insertion switch 2 which is closed when an ignition key is inserted into a key cylinder via a resistor R1 for supplying a small current and a diode D1 to thereby insert the key. Can be quickly detected by the comparator 50. Also,
If an oxide film is formed on the key insertion switch 2, the key insertion cannot be detected. Therefore, when the ignition switch 3 is turned on, a large current flows through the key insertion switch 2 via the main relay 21, the resistor R0, and the diode D0.
Breaks down oxide film. As a result, the power consumption of the battery 5 when the vehicle is parked with the key inserted in the key cylinder can be suppressed, and the key insertion can be detected without any problem.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch for closing an ignition switch such as a key insertion switch for detecting a state of insertion of an ignition key into a key cylinder and a seating switch for detecting that a vehicle driver is sitting in a driver's seat. The present invention relates to a vehicle switch state detection device that detects an open / close state of an on-vehicle switch whose open / close state is switched before being opened.

[0002]

2. Description of the Related Art Conventionally, an ignition key (hereinafter, referred to as an ignition key)
When the engine is started by rotating the key rotor by simply using the key), the ignition key inserted into the key cylinder is identified as genuine or fake, and the engine is started only if it is genuine. Permitted vehicle anti-theft devices are known.

In this vehicle anti-theft device, the power supply to the code collation device is started after an ignition switch (hereinafter, also simply referred to as an IG switch) is turned on (on state), whereby the code collation device is started. And causes the code collation device to execute communication between the key and the key for collating the password code on the key side with the password code on the vehicle side. Then, according to the matching result,
Allow or prohibit the engine control unit from starting the engine.

However, the conventional vehicle anti-theft device that activates the code collation device after the IG switch is turned on has the following problems.
That is, in order for the code collation device to perform the communication for the collation,
Usually, a time of about 100 to 500 (msec.) Is required. Therefore, if the code collation device is started after the IG switch is turned on, the above-mentioned communication is performed during the operation of the starter when the key operation from the IG switch on to the starter switch on is performed quickly. become. In this case, the communication is performed in a state where the output voltage of the battery is reduced due to the rotation of the starter, and a communication error is highly likely to occur.

Therefore, in order to accurately execute communication between the code collation device and the key, power is supplied to the code collation device before the IG switch is turned on, and the communication is completed when the starter operates. It is desirable to keep.
For this purpose, there is provided a key insertion switch for closing a contact by inserting a key into the key cylinder, and when the switch changes from an open (off) state to a closed (on) state, the key insertion switch is closed. The key insertion may be detected, power supply to the code collation device may be started, and the code collation device may be activated.

FIG. 10 shows an example of a power supply circuit in which a key insertion switch is provided as described above, and power supply to the code collating apparatus is started immediately after a key is inserted into a key cylinder. As shown in FIG. 10, the circuit includes a key insertion switch 72 which is turned on when a key is inserted into a key cylinder, a resistor Ra and a diode which form a power supply path for supplying power from the battery 78 to the key insertion switch 72. An inverting input terminal (-) is connected to the connection point between the resistor Da and the resistor Ra and the diode Da via a resistor Rb, and the power supply voltage from the battery 78 is connected to the non-inverting input terminal (+) with the resistors Rc and Rd. And a comparator 80 to which the reference voltage divided by is applied.

For this reason, when the key insertion switch 72 is off, the power supply voltage from the battery 78 is applied to the inverting input terminal (-) of the comparator 80 via the resistors Ra and Rb. The output from the battery 80 becomes low level, and when the key insertion switch 72 is turned on, the resistor Ra and the diode D
a, The current is flows through the path through the key insertion switch 72 to the ground line, the inverting input terminal (-) of the comparator 80 becomes low near the ground potential, and the output from the comparator 80 becomes high. .

That is, when the key is not inserted into the key cylinder and the key insertion switch 72 is in the off state, the output of the comparator 80 becomes low level, and the key is inserted into the key cylinder, and the key insertion switch is turned off. When 72 is turned on, the output of the comparator 80 goes high.

The output of the comparator 80 is connected to the base of an NPN transistor 82 whose emitter is grounded. The collector of the NPN transistor 82 has its emitter connected to the battery 78 (positive electrode side) via a resistor Re. The base of the connected PNP transistor 84 is connected, and the collector of the PNP transistor 84 is
Main relay 74 for supplying power to code collation device 76
Connected to the coil. The other end of this coil is
It is grounded to the ground of the same potential as the negative side of the battery 78.

Therefore, when a key is inserted into the key cylinder and the output of the comparator 80 becomes high level, NP
The N transistor 82 and the PNP transistor 84 are turned on, a current flows through the coil of the main relay 74, the contacts of the main relay 74 are closed, and power supply to the code collating device 76 is started.

Therefore, in the power supply circuit shown in FIG.
When a key is inserted into the key insertion switch 72, the code collation device 76 can be activated to collate whether the key inserted into the key cylinder is genuine.
The code collating device 76 communicates with a communication circuit provided on the ignition key side to read out a personal identification code registered in advance in a storage device on the ignition key side, and reads the personal identification code and the code collating device. The password is collated with the personal identification code registered on the 76 side, and when these codes match, the engine control device (not shown) is permitted to start the engine.

[0012]

Generally, an oxide film having an insulating effect is formed on the surface of the contact of the key insertion switch 72 with the passage of time. Therefore, when the current flowing through this switch is small, even if the key insertion switch 72 is mechanically closed, electrical connection cannot be secured by the oxide film. Therefore, in the above circuit, when the key insertion switch 72 is turned on,
In order to ensure that the current is flows through the key insertion switch 72, it is necessary to supply a large current sufficient to break through the oxide film. To secure this current is, the resistance Ra forming the current path is required. Must be set to a value as small as possible (for example, 1 KΩ or less).

However, in the above circuit, the current i
Since s flows only when the key is inserted into the key cylinder, if the resistance value of the resistor Ra is reduced and the current is increased (for example, to about 12 mA), for example, the IG switch is turned off to park the vehicle. To stop the engine,
Thereafter, when the vehicle is left with the key inserted in the key cylinder, the battery 78 is continuously discharged at the current is (eg, about 12 mA), and the battery 78 is discharged in a relatively short time (eg, two to three days). Is completely discharged.

That is, in an engine-equipped vehicle, during operation of the engine, the alternator is operated by the rotation of the engine to charge the battery.
There is no problem even if the current is flows through the key insertion switch 72. However, since the battery is not charged while the engine is stopped, when the current is flows, the battery is discharged by the current is. For this reason, for example, when the vehicle is kept in the garage at home for a long time, if the key is kept inserted into the key cylinder, the current i
As a result, the battery 78 is discharged by s, and the engine cannot be started within a few days after parking the vehicle.

Further, such a problem is not limited to the device for detecting the ON / OFF state of the key insertion switch 72. For example, a door switch for detecting the open / closed state of a vehicle door,
A device that detects the open / closed state of an in-vehicle switch, such as a seat switch that detects that the driver is sitting in the driver's seat, that is opened / closed before the IG switch is closed (in other words, when the engine is stopped), Occurs in the same way as

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and is directed to a device for detecting the open / closed state of an on-vehicle switch which is switched between open and closed states before an IG switch is closed. It is an object of the present invention to sufficiently suppress the power consumption of the battery and detect the open / closed state without being affected by the oxide film formed on the contact point of the on-vehicle switch.

[0017]

According to a first aspect of the present invention, there is provided a vehicle switch state detecting device, comprising:
Power is supplied to the in-vehicle switch from the second path, and when the ignition switch is closed, power is supplied to the in-vehicle switch from the first path and the second path.

Therefore, if the on-vehicle switch is closed when the ignition switch is open, the second current limited by the second limiting means flows through the on-vehicle switch, and the on-vehicle switch is closed when the ignition switch is closed. When the switch is in the closed state, a large current obtained by combining the second current limited by the second current limiting means and the first current limited by the first current limiting means flows through the on-vehicle switch.

Since the current flowing when the ignition switch is closed is equal to or more than the first current sufficient to break through the oxide film formed on the contact point of the on-vehicle switch, the on-vehicle switch is closed when the ignition switch is closed. In this state, even if an oxide film is formed on the on-vehicle switch, a current flows through the on-vehicle switch, and the closed state of the on-vehicle switch can be detected by the detection unit. Also, once the current flows through the on-vehicle switch, the oxide film formed on the contact is destroyed, and if the on-vehicle switch is closed, a low-resistance current path is formed. Allows a very small current that cannot penetrate the oxide film to flow.

On the other hand, when the ignition switch is opened, the current flowing through the on-vehicle switch is limited to the second current. Therefore, when the on-vehicle switch is closed when the ignition switch is opened, an oxide film is formed on the on-vehicle switch. If this is done, no current flows in the on-vehicle switch, and the detection means cannot detect the closed state of the on-vehicle switch.

However, when the vehicle is frequently driven, a large current equal to or greater than the first current flows when the vehicle-mounted switch is closed each time the vehicle is driven. When the ignition switch is closed and the on-vehicle switch is closed without the formation of a high-resistance oxide film through which the second current can flow, the detection means quickly switches the on-vehicle switch to the closed state. Can be detected.

Even if the vehicle is left undisturbed for a long period of time and an oxide film that cannot be broken through by the second current is formed on the contact of the vehicle-mounted switch, if the vehicle-mounted switch becomes closed when the ignition switch is closed, Since the oxide film was destroyed by a large current of 1 current or more and current flowed to the on-vehicle switch, the closed state of the on-vehicle switch could be detected by the detection means. Since the second current can be passed to the on-vehicle switch at the time, the closed state of the on-vehicle switch can be detected by the detecting means without any problem.

As described above, according to the present invention, even when the second current flowing through the on-vehicle switch when the ignition switch is opened is set to a current that cannot break through the oxide film formed on the on-vehicle switch, the on-off switch of the on-vehicle switch is opened and closed. Since the state can be detected without any problem, the second current is set to a sufficiently small current value, and the current (so-called dark current) flowing through the on-vehicle switch when the ignition switch is opened (in other words, when the engine is stopped) is set. By reducing the size, discharge from the battery can be suppressed.

Therefore, according to the present invention, when the vehicle is parked while the on-vehicle switch is switched to the closed (on) state, the period until the battery is discharged to such an extent that the engine cannot be started is made sufficiently long. And protect the battery from discharging.

In order to suppress the discharge of the battery when the ignition switch is opened, the second current limiting means is used to reduce the second current flowing from the second current to the on-vehicle switch by one.
It is desirable to configure so as to limit it to mA or less. Here, the current limiting means provided on the first path and the second path only needs to be able to limit the current flowing to the on-vehicle switch via each path to the first current or the second current. For example, a transistor is used for each path. Current limiting circuit may be provided. However, in a current limiting circuit using a transistor, the circuit configuration becomes complicated.
As described in claim 2, each of the current limiting means is constituted by a resistor provided in series in each path, and a resistance value of the first resistor provided in the first path is provided in a second path. The second
What is necessary is just to make it small compared with the resistance value of a resistor. That is, if each current limiting means is configured in this manner, the second current can be limited to a current value smaller than the first current, and
Since it can be realized with only two resistors, the configuration of the device can be extremely simplified.

As the on-vehicle switch, for example, a door switch which is turned on / off by inserting an ignition key into a key cylinder provided on a vehicle door,
The above-described effects can be obtained by applying the present invention to any switch that switches between open and closed states before the ignition switch is closed, such as a seat switch that detects that the driver is sitting on the seat.

For example, if the present invention is applied to a device for detecting the open / closed state of a key insertion switch which is closed when an ignition key is inserted into a key cylinder, as described in claim 3, It is possible to quickly detect that the ignition key has been inserted into the key cylinder before the ignition switch is closed,
By detecting that the driver is trying to start the engine by inserting the ignition key into the key cylinder, it is possible to quickly start the device that executes the predetermined control.

The device according to claim 3 reads the identification code for key authentication from the storage means incorporated in the ignition key as described in claim 4, and the ignition key is read from the identification code by the ignition key. If the ignition key is applied to a vehicle equipped with anti-theft collation means that allows the engine to start when the ignition key is a key for the vehicle, the ignition key is used as a key cylinder. Immediately after the insertion, the collating means can be activated immediately, and the collation of the ignition key inserted into the key cylinder can be executed before the ignition key is closed.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle antitheft device according to an embodiment of the present invention will be described below. The anti-theft device according to the present embodiment has a function as a vehicle switch state detecting device that detects that an ignition key has been inserted into a key cylinder, and determines whether the ignition key is a key for the vehicle. The function as the collation means and the function as the engine control means for controlling the engine are incorporated in one electronic control unit 7 so that the function as the antitheft device can be realized.

FIG. 1 is a block diagram showing the overall configuration of the electronic control unit 7 and peripheral devices connected thereto. FIG. 2 shows the appearance of a key cylinder 31 provided on a steering column portion of the vehicle. FIG. In a key (ignition key) 1 shown in FIG. 1, a storage device (storage means) such as a ROM in which a personal identification code is stored in advance.
And a capacitor in which electric charges are stored in accordance with electric power (radio waves) transmitted from the amplifier 16 via the antenna 17, and read out a personal identification code from a storage device using the electric charges stored in the capacitor as a power supply and transmit the code to the antenna 17. And a built-in transmitter. When the key 1 is inserted into the key cylinder 31 shown in FIG. 2, the key insertion switch 2 shown in FIG. 1 is mechanically closed.

A positive voltage is applied to one contact of the key insertion switch 2 from the main relay control unit 15 via a power supply path 22, and the other contact has the same potential as the negative electrode of the battery 5. Grounded. Therefore, the power supply path 22 of the key insertion switch 2 becomes low level (0 V) when the key insertion switch 2 is closed, and becomes high level when the key insertion switch 2 is opened.

In the key cylinder 31 shown in FIG. 2, when the key 1 is inserted and rotated, and the key rotor 32 is turned to the "ON" position, the IG switch (ignition switch) 3 shown in FIG. Close to. IG
The switch 3 has one contact connected to the positive electrode side of the battery 5 and the other contact connected to a power supply line 23 that supplies power to various parts of the vehicle. Therefore, the power supply line 23
Goes to a high level (battery voltage) when the IG switch 3 is closed, and goes to a low level when the IG switch 3 is opened.

In the key cylinder 31, the key 1
Is further rotated, and the key rotor 32 is moved to the “STA” shown in FIG.
In the "RT" position, the starter switch 4 shown in FIG. 1 is mechanically closed. Then, power is supplied from the battery 5 to the starter 6, and the starter 6 starts.

On the other hand, as shown in FIG. 1, the electronic control unit 7 includes an engine control unit 8, an EEPR0M10,
Third transistors (PNP transistors) 11 to 13,
A power supply control unit 14 and a main relay control unit 15 are provided. The first transistor 11 has an emitter connected to the battery 5.
, The base is connected to the main relay control unit 15, and the collector is connected to the coil 21 a of the main relay 21. Since the other end of the coil 21a is grounded, the first transistor 11
Is turned on, the coil 21a is energized, and the contact 21b of the main relay 21 is closed.

The second transistor 12 has an emitter connected directly to the positive electrode of the battery 5, a base connected to the power supply control unit 14, and a collector connected to the main relay control unit 1.
5 is connected. Also, the third transistor 13
The emitter is connected to one of the contacts 21b of the main relay 21, the base is connected to the power control unit 14, and the collector is connected to the engine control unit 8, the EEPR0M10, the main relay control unit 15, the amplifier 16, and the like. The other of the contacts 21b of the main relay 21 is connected to the positive electrode of the battery 5.

The power supply control unit 14 receives power directly from the battery 5 and is always in operation, and the collector voltages of the second transistor 12 and the third transistor 13 are set to a predetermined voltage (5 V in this embodiment). The base voltage of each of the transistors 12 and 13 is controlled so that Therefore, the main transistor control unit 15
Is always supplied with a voltage of 5 V via a power supply line 28 connected to the collector of the second transistor 12, and the main relay control unit 15 is always in an operating state.

The main relay control unit 15 includes a power supply path 22
Has a function as a detecting means for detecting a key insertion into the key cylinder 31 by determining whether or not a current flows through the key insertion switch 2 via the switch. When the key insertion is detected, the first transistor 11 is turned on. Then, the contact 21b of the main relay 21 is closed. When the main relay 21 is turned on in this manner, power is supplied from the battery 5 to the collector of the third transistor 13, and various parts in the electronic control unit 7 (engine control unit 8, EEPROM 10, and Amplifier 1
For 6), a power supply voltage of 5 V is supplied.

Therefore, in this embodiment, the key cylinder 31
Immediately after the key 1 is inserted and the key insertion switch 2 is closed, the engine control unit 8 is activated. When activated, the engine control unit 8 reads out the password from the key 1 and stores the password and the EEPROM 1
By comparing the key cylinder 3 with the password stored in the key 0 (the password stored in the vehicle), the key cylinder 3
A code collation process is performed as collation means for determining whether or not the key 1 inserted in the key 1 is a key for the vehicle.
8. Engine control processing as engine control means for calculating the fuel injection amount, ignition timing, and the like based on signals from the rotation angle sensor 19 and the like, and driving the injector 20a, the igniter 20b, and the like based on the calculation results. To start. Therefore, in the present embodiment, before the IG switch 3 is closed, the code comparison processing by the engine control unit 8 can be executed. Note that the engine control unit 8
At the time of executing the engine control, a learning value of the engine 20 (for example, a learning value of the air-fuel ratio) is written in the EEPROM 10.

Next, the engine control unit 8 comprises an input / output port 8a, a CPU 8b, a ROM 8c, a RAM 8d and the like. The input / output port 8a has an amplifier 16
The transmission / reception switching port 8a1 for switching the operation mode between a transmission mode for transmitting radio waves from the antenna 17 and a reception mode for receiving a password from the key 1.
Is provided. The transmission / reception switching port 8a1
When a high-level signal is output from the
When the transmission mode is set and the radio wave transmitted to the key 1 via the antenna 17 is modulated and amplified, and a low-level signal is output from the transmission / reception switching port 8a1, the amplifier 16 is set in the reception mode and the key 1 is switched to the reception mode. Demodulates the personal identification code transmitted from.

On the other hand, the CPU 8b retains the above-mentioned EE that retains the stored contents even when the power supply from the battery 5 is cut off.
The PROM 10 is connected. This EEPR0M10
An area 10a for storing a theft determination flag indicating the result of collation of the two security codes, an area 10b for storing the learning value for the engine 20, and an area 10c for storing the vehicle-side security code. Is formed.

Next, the engine control unit 8 (specifically, the CPU
8b) shows a code collation process executed immediately after startup to prevent theft and an interrupt process for permitting or prohibiting the execution of the engine control process according to the result of the code collation process. Description will be given along a flowchart.

First, FIG. 3 shows a code collation process performed only once as an initial routine by the CPU 8b after performing various initial settings immediately after turning on the power. As shown in FIG. 3, when this process is started, it is determined in S100 (S represents a step) whether or not the key insertion switch 2 is closed. When the key insertion switch 2 is inserted into the key cylinder 31 and the engine control unit 8 is started up in a normal operation, the determination is YES, and the process proceeds to S110.

In S110, the error counter in the RAM 8d is cleared (set to 0), and in S115, the output from the transmission / reception switching port 80a1 is output for a predetermined time (for example, 5 seconds).
0 ms) High level. As a result, the amplifier 16 enters the transmission mode, and the electric power (radio wave) amplified by the amplifier 16 continues to be transmitted to the key 1 via the antenna 17 for a predetermined time, and the electric charge is stored in the capacitor in the key 1. Here, the predetermined time is a time sufficient for the amount of electric charge stored in the capacitor of the key 1 to be able to serve as a power source of a transmitter in the key 1.

Next, in S120, the transmission / reception switching port 80
The output from a1 is switched to low level, the amplifier 16 is set to the reception mode, and it is determined whether or not the key 1-side password transmitted from the amplifier 16 has been received. That is, when the amplifier 16 is set to the reception mode, the power supply to the key 1 is cut off, the transmitter in the key 1 transmits the security code, and the amplifier 16 demodulates the security code, and the transmission / reception switching port Since the demodulated personal identification code is transferred to 80a1, it is determined in S120 whether the personal identification code of the key 1 has been received. And key 1
Until the personal identification code is received, the processes of S115 and S120 are repeatedly executed.
It moves to 25.

In S125, area 1 of EEPR0M10
The personal identification code stored in 0c is loaded. And
In the next S130, the password from the key 1 and the EEPR
The password is collated with the security code from the OM 10, and when both security codes match, it is determined that the key 1 inserted into the key cylinder 31 is for the vehicle and that the vehicle has not been stolen. The theft determination flag in the EEPR0M10 is set to 0, and the process ends. That is, the fact that the vehicle was not stolen is stored in the EEPR0M10.

On the other hand, when the passwords do not match, S
The routine proceeds to 135, where the error counter is incremented by one, and in S140, it is determined whether or not this error counter has exceeded a predetermined number (10 in this embodiment). When the error counter does not exceed 10, the process returns to the snub 115, and the above-described processing is repeated. When the error counter exceeds 10, it is determined that the correct password cannot be received, and in the next S150, the theft determination in the EEPROM 10 is performed. The flag is set to 1, the warning lamp 27 shown in FIG. 1 is turned on, and the process is terminated.

FIG. 4 shows an interruption process (interruption routine) executed at predetermined intervals (for example, 4 msec.) In the engine control unit 8 (specifically, the CPU 8b). In this interrupt routine, first, in S300, the EEPR0M1
It is determined whether or not the theft determination flag written to “0” is set to “0”. That is, it is determined whether or not the vehicle has been stolen. When the theft determination flag is set to 0, the fuel injection flag and the ignition flag are set to 1 in S305 and S310, and conversely, when the theft determination flag is set to 1, in S315 and S310.
At 320, the fuel injection flag and the ignition flag are set to 0, and the process ends.

Engine control unit 8 (specifically, CPU 8b)
Performs engine control such as fuel injection and ignition when the IG switch 3 is closed in an engine control process (not shown). In this engine control, if the fuel injection flag is set to 1, the injector 20a
Control to send a fuel injection pulse to the igniter 20b if the ignition flag is set to 1. However, when the fuel injection flag is set to 0, the transmission of the fuel injection pulse to the injector 20a is prohibited, and when the ignition flag is set to 0, the transmission of the ignition pulse to the igniter 20b is prohibited. Ban. That is, when the fuel injection flag and the ignition flag are set to 1, the start of the engine 20 is permitted, and when the fuel injection flag and the ignition flag are set to 0, the start of the engine 20 is prohibited.

Therefore, in the present embodiment, if the code stored in the key 1 matches the code stored in the vehicle as a result of the code collation processing, and the password determined by the theft determination flag is set to 0, Only (that is, only when it is determined that the vehicle has not been stolen), the engine 20 can be started, and theft of the vehicle can be prevented.

Next, the configuration of the main relay control unit 15, which is a main part of the present invention, will be described with reference to FIG.
As shown in FIG. 5, in the main relay control unit 15, a power supply path 22 connected to one contact of the key insertion switch 2.
Is connected to the cathode of the diode D1. The anode of the diode D1 is connected to the resistor R1 and the power supply line 28.
Is connected to the collector of the second transistor 12 via the resistor R2 and to the inverting input terminal (-) of the comparator 50 via the resistor R2. Since the second transistor 12 always outputs 5 V from the collector, the power is always supplied to the key insertion switch 2 via the resistor R1 and the diode D1. Therefore, when the key insertion switch 2 is open, the inverting input terminal (-) of the comparator 50 is at the high level (5 V).
When the key 1 is inserted into the key cylinder 31 and the key insertion switch 2 is electrically closed, the inverting input terminal (-) of the comparator 50 becomes low level (about 0 V).

In this embodiment, the second transistor 12, the power supply line 28, the resistor R
Since power is always supplied to the key insertion switch 2 via the diode 1, the diode D1, and the power supply path 22, the power supply path including these components corresponds to the second path of the present invention. Since the current flowing through the key insertion switch 2 via the path is limited by the resistor R1, the resistor R1 functions as a second current limiting unit. In this embodiment, by setting the resistance value of the resistor R1 to a large value (for example, 51 kΩ), the current flowing through this path when the key insertion switch 2 is closed is 0.1 m.
A small current (second current) of about A is set.

Next, the non-inverting input terminal (+) of the comparator 50 is connected to the connection point of the resistors R3 and R4 for dividing the voltage (5 V) of the power supply line 28, and the potential is
The reference potential (for example, 2.5 V) determined by the resistance ratio of the resistors R3 and R4 is maintained. Therefore, when the key insertion switch 2 is in the open state and the potential of the non-inverting input terminal (-) is at the high level, a low-level signal is output from the comparator 50. Is closed and the potential of the non-inverting input terminal (-) becomes low level, the comparator 50 outputs a high level signal. Note that the comparator 50 is always operated by receiving power supply from the second power supply line 28. In the present embodiment, the comparator 50
0 functions as detecting means for detecting the open / closed state of the key insertion switch 2.

On the other hand, the output terminal of the comparator 50
The timer circuit 51 is connected. The timer circuit 51
The comparator 50 detects the closed state of the key insertion switch 2 and measures the elapsed time from when its output goes to a high level. After the start of the time measurement, the elapsed time reaches a predetermined time (for example, one minute). Until it outputs a high level signal. The output from the timer circuit 51 is
The signal is input to the OR circuit 54. Accordingly, a high-level signal is always output from the OR circuit 54 until a predetermined time (1 minute) elapses after the comparator 50 detects the closed state of the key insertion switch. .
Note that the timer circuit 51 has a second
Power is supplied from a power supply line 28 so that the power supply 28 can always operate.

Next, the output signal from the comparator 52 is input to the OR circuit 54 in addition to the output signal from the timer circuit 51. This comparator 52 has an IG
This is for detecting the open / close state of the switch 3, and a reference voltage divided by the voltage dividing resistors R3 and R4 is applied to the inverting input terminal (-). The non-inverting input terminal (+) of the comparator 52 is connected to the other end of the grounded resistor R5 and the power supply line 23 from the IG switch 3 via the resistor R6.

Therefore, when the IG switch 3 is open, the non-inverting input terminal (+) of the comparator 52 goes low (0 V), and the output from the comparator 52 goes low. When 3 is closed, the non-inverting input terminal (+) of the comparator 52 goes high (battery voltage; 12 to 14 V), and a high-level signal is output from the comparator 52. The comparator 52, like the comparator 50 and the timer circuit 51, receives power supply from the second power supply line 28 and can always operate.

Therefore, the output from the OR circuit 54 is determined not only by the time the predetermined time (one minute) elapses after the closed state of the key insertion switch is detected by the comparator 50 but also by the key operation of the driver. Also when the IG switch 3 is closed, it is at the high level.

Next, the output of the OR circuit 54 is a resistor R
The emitter is connected to the base of a grounded NPN transistor 56 via. The collector of the NPN transistor 56 is connected to the base of the first transistor 11 via the resistor R8. For this reason, NP
The N-transistor 56 and the first transistor 11 operate until a predetermined time (1 minute) elapses after the comparator 50 detects that the key insertion switch 2 is closed, and
When the IG switch 3 is closed, it is turned on. During that time, the contact of the main relay 21 is closed and power is supplied to the engine control unit 8 and the like.

In this embodiment, a resistor R1 is provided in a power supply path (second path) from the power supply line 28 to which the power is always supplied via the second transistor 12 to the key insertion switch 2, and the resistance R1 is provided. By increasing the resistance value of R1, the current (dark current) flowing when the key 1 is inserted into the key insertion switch 2 when the IG switch 3 is opened (in other words, when the engine 20 is stopped) is reduced to 0. A very small current of about 1 mA is set.

For this reason, the amount of power consumption of the battery 5 generated when the vehicle is parked with the key 1 inserted in the key cylinder 31 is suppressed, and the battery 5 is discharged until the engine 20 cannot be started. Although the period can be lengthened, if an oxide film is formed on the contact of the key insertion switch 2, a large current that can break through the oxide film when the key insertion switch 2 is closed cannot flow, The closed state of the key insertion switch 2 cannot be detected by the comparator 50.

Therefore, in this embodiment, the main relay 21
A power supply path (first path) 60 for connecting a power supply line from the power supply line to the third transistor 13 and the power supply path 22 connected to the contact point of the key insertion switch 2 is formed. Even if the diode D0 is provided in series and the current cannot flow from the second path to the key insertion switch 2 due to the oxide film formed on the contact of the key insertion switch 2, A large current that penetrates the oxide film formed on the key insertion switch 2 can be passed.

That is, in this embodiment, the resistance value of the resistor R0 as the first current limiting means provided in the power supply path 60 is reduced (for example, 1 kΩ) so that the main relay 21 is closed. The current flowing through the key insertion switch 2 is determined by the resistance value of the resistor R0 and the battery voltage (12 to
14V), the current is limited to a large current (first current) of about 12 to 14 mA, and an oxide film formed on the key insertion switch 2 can be broken by this large current.

The diode D0 provided in the power supply path 60 has an anode connected to the main relay 2 via a resistor R0.
1, and the cathode is connected to the contact of the key insertion switch 2 via the power supply path 22. And
The diode D0 on the first path side and the diode D1 on the second path side each function as backflow prevention means for preventing backflow of current from the other path.

In the vehicular anti-theft device of the present embodiment configured as described above, as shown in FIG. 6, when the oxide film is not formed on the contact of the key insertion switch 2, the key cylinder 31 When the key 1 is inserted and the key insertion switch 2 is turned on (closed) (time t1), a minute current (second current) flows through the key insertion switch 2 and the comparator 50 turns on the key insertion switch 2. Is detected, and the main relay 21 is turned on (closed). For this reason, the engine control unit 8 can be started immediately after the key 1 is inserted into the key cylinder 31, and then the IG switch 3 is turned on (closed) by the key operation of the driver, and the starter is further driven. In the meantime, the engine control unit 8 can check whether the ignition key inserted into the key cylinder 31 is genuine.

Further, the IG switch 3 is turned off (closed),
After the key insertion switch 2 is pulled out of the key cylinder 31 (time point t2), the key insertion switch 2 is left for a long time (for example, about one month) to form an oxide film on the contact of the key insertion switch 2. 1 is inserted,
Even if the key insertion switch 2 is turned on (time t
3), a small current (second current) cannot flow through the key insertion switch 2, and the comparator 50 cannot detect the ON state of the key insertion switch 2; However, after that, when the IG switch 3 is turned on (time t4),
Since the main relay 21 is turned on and the engine control unit 8 is started, the ignition key verification may not be completed before the starter is driven, but the engine 20 can be started without any problem. .

Once the main relay 21 is turned on, a large current (first current) flows through the key insertion switch 2 and the oxide film formed on the contact is broken. It is turned off (closed) and the key insertion switch 2 is removed from the key cylinder 31 (at time t).
5) Unless an oxide film that cannot allow a small current to flow through the key insertion switch 2 before the engine 20 is started next time, the key 1 is inserted into the key cylinder 31 to start the engine 20. At this time (time t6), the ON state of the key insertion switch 2 is immediately detected by the comparator 50. Further, for example, even if the key 1 is not removed from the key cylinder 31 after the IG switch 3 is closed (time t7) and the engine 20 is stopped, and the key insertion switch 2 is kept on,
When the switch 3 is turned off, the main relay 21 is also turned off, so that the current flowing through the key insertion switch 2 is switched from a large current that can destroy the oxide film to a small current (second current). For this reason, the power consumption of the battery 5 when the vehicle is parked with the key 1 inserted into the key cylinder 31 can be suppressed, and the battery 5 is discharged to such an extent that the engine 20 cannot be started during the parking period. The period up to can be lengthened.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various embodiments can be adopted. For example, in the above embodiment, the power supply path 60 as the first path is connected to the main relay 2
Although the power supply path is directly received from the battery 5 via the power supply line 1, the power supply path 60 allows a large current (first current) to flow to the key insertion switch 2 when the IG switch 3 is turned on. As shown in FIG. 7, the power supply path 60 is connected to the power supply line 23 directly connected to the battery 5 via the IG switch 3, and power is supplied to the power supply path 60 only when the IG switch 3 is turned on. It may be configured to be supplied.

Then, when the IG switch 3 cannot be turned on after the key 1 is inserted into the key insertion switch 2 as in the above embodiment, a large current ( There is no need to provide a timer circuit 51 for preventing the first current) from continuing to flow,
Since the output from the comparator 50 may be directly input to the OR circuit 54, the configuration of the main relay control unit 15 can be simplified as compared with the above embodiment.

The power supply path 60 as the first path is
For example, as shown in FIG. 8, a resistor R1 forming a second path for always supplying power to the key insertion switch 2 is formed in parallel with the resistor R1. A switching element (PNP transistor) 62 for conducting and blocking the path 60 is provided, and the output of the comparator 52 is input to the base of the PNP transistor 62 via the inverter 64 so that the IG switch 3 is turned on by the comparator 52. Only when a state is detected, the PNP transistor 62 may be turned on to make the power supply path 60 conductive. That is, even with such a configuration, a large current can flow through the key insertion switch 2 only when the IG switch 3 is turned on, and the same effect as that shown in FIG. 7 can be obtained.

In FIG. 8, the power supply path 60 is
The PNP transistor 62 to be cut off has the collector R
IG switch 3 is connected to the anode of diode D1 (extendedly, the contact of key insertion switch 2) via a line 0, the emitter is connected to power supply line 28 that is always supplied with power via second transistor 12, and Is turned on, and the signal from the comparator 52 goes to a high level, the base potential is switched to a low level by the operation of the inverter 64 to be turned on.

The power supply path 60 as the first path is
For example, as shown in FIG. 9, an NPN having a collector connected to the positive electrode side of the battery and an emitter connected to the resistor R0.
The NPN transistor 66 is controlled by the engine control unit 8 to control the IG
The switch 3 may be turned on only when the switch 3 is turned on.

That is, when the power supply path 60 is configured as shown in FIG. 9, when a high-level signal is input to the base of the NPN transistor 66, the NPN transistor 66 is turned on, and the NPN transistor 66 and the resistor Power is supplied to the key insertion switch 2 through R 0, the diode D 0, and the power supply path 22, and a large current (first current) flows through the key insertion switch 2. NPN transistor 66
Is turned on only when the IG switch 3 is turned on, the same effect as that shown in FIGS. 7 and 8 can be obtained.

On the other hand, in the above embodiment, the case where the present invention is applied to the open / closed state detecting device of the key insertion switch 2 in the vehicle antitheft device has been described.
The same effect as in the above embodiment can be obtained as long as the switch detects the open / closed state of the on-vehicle switch whose open / close state is switched before the G switch 3 is closed. That is, for example, an IG such as a door switch that is turned on / off by inserting a key into a key cylinder provided on a vehicle door, a seat switch that detects that a driver is sitting on a seat, or the like.
Even when the present invention is applied to a device that detects the on / off state (open / closed state) of a switch in which the switch state changes before the switch is closed, the same effect as in the above embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an overall configuration of a vehicle antitheft device according to an embodiment.

FIG. 2 is an explanatory diagram illustrating a key insertion portion of a key cylinder.

FIG. 3 is a flowchart illustrating a code collation process executed as an initial routine by an engine control unit.

FIG. 4 is a flowchart illustrating an interrupt process executed by an engine control unit.

FIG. 5 is an electric circuit diagram illustrating a configuration of a main relay control unit.

FIG. 6 is a time chart illustrating an operation of a main relay control unit.

FIG. 7 is an electric circuit diagram illustrating a second configuration example of the main relay control section.

FIG. 8 is an electric circuit diagram illustrating a third configuration example of the main relay control unit.

FIG. 9 is an electric circuit diagram illustrating a fourth configuration example of the main relay control unit.

FIG. 10 is an electric circuit diagram showing a conventional circuit configuration example for detecting the open / close state of a key insertion switch.

[Description of Signs] 2 ... Key insertion switch 3 ... IG switch (ignition switch) 7 ... Electronic control unit 8 ... Engine control unit 15
... Main relay control unit 20 ... Engine 21 ... Main relay 31 ... Key cylinder 50 ... Comparator (detection means) R0 ... Resistor (first
Current control means) R1 ... resistance (second current control means)

Claims (4)

[Claims] 1. A power supply path for supplying power to an in-vehicle switch whose opening / closing state is switched before an ignition switch is closed so that a current flows when the in-vehicle switch is closed; And a detecting means for detecting a closed state of the on-vehicle switch when a current flows through the on-vehicle switch, wherein a power supply is performed when the ignition switch is closed as the power supply path. A first path and a second path for constantly supplying power regardless of the open / closed state of the ignition switch.
A first current limiting means for flowing a first current sufficient to break through an oxide film formed at a contact point of the on-vehicle switch when the on-vehicle switch is closed; 2
The vehicle switch state detection device, wherein a second current limiting means for supplying a second current smaller than the first current when the on-vehicle switch is closed is provided on the path. 2. Each of the current limiting means includes a resistor provided in series with each of the paths, and a resistance value of a first resistor provided on the first path is equal to a resistance value of a first resistor provided on the second path. 2
2. The method according to claim 1, wherein the resistance is smaller than a resistance value of the resistance.
2. The vehicle switch state detecting device according to claim 1. 3. The switch state for a vehicle according to claim 1, wherein the on-vehicle switch is a key insertion switch that closes when the ignition key is inserted into a key cylinder. Detection device. 4. A vehicle, comprising: an engine control means for starting an engine when the ignition switch is closed to control the engine; and reading a key identification code from a storage means in an ignition key inserted into the key cylinder. Determining whether the ignition key inserted into the key cylinder is a key for the vehicle from the code, and when the ignition key is a key for the vehicle, the engine control means 4. The vehicle according to claim 3, further comprising: anti-theft checking means for permitting the start, and wherein the detecting means activates the checking means when detecting the closed state of the key insertion switch. Switch state detector.