JPH06270764A - Burglarproof device for vehicle - Google Patents

Abstract

PURPOSE:To connect a key detecting circuit and an engine control circuit to each other by plural communication wires to detect the cause of the disconnection of the communication wires. CONSTITUTION:In a vehicular robbery preventing device provided with a key unit 1, a key detecting circuit 2 and an engine control circuit 3, plural communication wires are provided between the key detecting circuit 2 and the engine control circuit 3. The key detecting circuit 2 sends out engine start permission signals to all the communication wires in the case of a key code from the key unit 1 coinciding with the set code, and the engine control circuit 3 starts an engine when the engine start permission signal is inputted to either communication wire. The engine control circuit 3 also detects whether the communication wire is disconnected, and in the case of plural communication wires are disconnected, clocks the disconnected time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle antitheft device for detecting the code set in a key to determine whether or not to permit engine start to prevent the vehicle from being stolen.

[0002]

2. Description of the Related Art Since a vehicle such as an automobile may be unlocked illegally for the purpose of theft, a vehicle antitheft device has been proposed for the purpose of preventing theft due to illegal unlocking. For example, in Japanese Patent Laid-Open No. 63-93649, a primary coil wound around an annular core provided on a lock and a secondary coil wound around an axial core provided on a key are magnetically coupled, and the magnetic coupling is performed by the magnetic coupling. There is disclosed a vehicle antitheft device that detects a flowing current value and determines whether or not a correct key is inserted.

FIG. 4 shows an antitheft device for a vehicle of this type, in which the key 11 is inserted by inserting the key 10 into the lock 11.
The primary coil (not shown) and the secondary coil (not shown) of the key 10 are magnetically coupled to each other, and the resonance circuit provided inside the key 10 resonates only when the frequency of the oscillator of the lock 11 has a certain value. The current flowing through the primary coil increases sharply. When it is detected that the frequency of the oscillator when the current rapidly increases matches the frequency preset in the lock 11, the key detection circuit 20 allows the engine control circuit 30 to start the engine.

[0004]

In such a conventional vehicle antitheft device, since the key detection circuit 20 and the engine control circuit 30 are connected by one communication line L10, this communication line L10 is connected. When the wire is broken, the key detection circuit 20
Cannot output engine start information from the engine control circuit 30. Therefore, the engine control circuit 30 cannot determine whether the engine start permission state or the engine start prohibition state is reached, and if the engine start permission state is mistakenly determined, the theft prevention function does not work.
When it is determined that the engine start is prohibited, there is a problem that the engine cannot be started.

An object of the present invention is to determine whether or not a disconnection is due to theft by communicating key information using a plurality of communication lines and measuring a time interval at which each communication line is disconnected. Another object of the present invention is to provide a more reliable vehicle antitheft device.

[0006]

The present invention will be described with reference to FIG. 1 showing an embodiment. In the present invention, the information detecting means 2 for detecting the information set in a key and outputting a detection signal.
And an engine control means 3 for determining whether to permit engine start by a detection signal sent from the information detection means 2 through a communication line, and applied to a vehicle antitheft device, and between the information detection means 2 and the engine control means 3. Are connected by a plurality of communication lines L1 and L2, the detection signal is received by the engine control means 3 through the plurality of communication lines, and the engine control means 3 is disconnected by one or more communication lines among the plurality of communication lines. Disconnection detecting means for detecting that the communication line has been disconnected, measuring means for measuring the time interval at which each communication line has been disconnected, and prohibiting means for prohibiting engine start when the measured time interval is shorter than a predetermined time. By doing so, the above object is achieved.

[0007]

The information detecting means 2 detects the information set in the key and inputs this detection signal to the engine control means 3 through the plurality of communication lines L1 and L2. When two or more communication lines among the plurality of communication lines are disconnected, the disconnection detection means detects the disconnection and the time interval of each disconnection is measured by the measurement means, and the time interval is shorter than the predetermined time. For example, the engine control means 3 prohibits engine starting.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0009]

1 is a block diagram of a vehicle antitheft device according to the present invention. Reference numeral 1 denotes a key unit composed of a key 10 and a lock 11. Inside the key 10, there is a secondary coil L2 connected in series, a coil L21 forming a resonance circuit with the secondary coil L2, and a capacitor C. Is provided. The lock 11 has primary coils L11 and L12 connected in series and having the same number of turns but wound in opposite directions, a resistor R, and a variable frequency oscillator 1 for continuously varying the frequency.
2 is provided, and when the key 10 is inserted into the lock 11, the primary coils L11 and L12 are magnetically coupled with the secondary coil L2 of the key 10, and a current flows in the series circuit of the lock 11. Further, the lock 11 has a current detection circuit 13 for detecting a current flowing through the series circuit, and the current detection circuit 12
And an A / D converter 14 for converting the signal amplified and rectified by the above into a digital signal.

Reference numeral 2 denotes a key detection circuit, which is used when the key 10 is inserted into the lock 11 and the ignition ON position (hereinafter referred to as IGN-
When it is set to the ON position), the digital signal indicating the key code from the key unit 1 is compared with the setting code preset in the key detecting circuit 2 to judge whether or not the correct key is inserted. . The key detection circuit 2 and the engine control circuit 3 are connected by two communication lines L1 and L2, and the same signal is sent to both communication lines. That is, when it is determined that the correct key is inserted, an engine start permission signal is output, and when it is determined that the wrong key is inserted, an engine start prohibition signal is output.
Input to the engine control circuit 3 through 1 and L2. Therefore, the engine control circuit 3 starts the engine when the engine start permission signal is input to either of the two communication lines. In FIG. 1, the port of the key detection circuit 2 of the communication line L1 is A, the port of the corresponding engine control circuit 3 is C, the port of the key detection circuit 2 of the communication line L2 is B, and the port of the corresponding engine control circuit 3 is The port is D. In addition, the key detection circuit 2 and the engine control circuit 3 are
By a signal line (not shown), the key 10 is in the IGN-ON position or the ignition OFF position (hereinafter IGN-OF
A signal indicating which of the F positions) is input from the key unit 1.

FIG. 2 is a flow chart showing the operation of the key detection circuit 2. In the flow chart of Fig. 2, the key is IG
The operation starts when it is operated from the N-OFF position to the IGN-ON position. In step S1, it is detected whether the key code matches the set code. Ie key 1
It is detected whether or not the key code obtained by converting the current value flowing when 0 and the lock 11 are magnetically coupled into each other into a digital signal and the setting code match. If the key codes match, the process proceeds to step S2, from the A port to C of the engine control circuit 3.
Output an engine start permission signal to the port. Next, in step S3, from the B port to the D of the engine control circuit 3
An engine start permission signal is output to the port, and the process ends. If the key codes do not match in step S1, the process proceeds to step S4, the engine start prohibition signal is output from the A port to the C port of the engine control circuit 3, and then the B port outputs D of the engine control circuit 3 in step S5. An engine start permission signal is output to the port, and the process ends.

FIG. 3 is a flow chart showing the operation of the engine control circuit 3. The flowchart of FIG. 3 starts the operation when the key is operated from the IGN-OFF position to the IGN-ON position. In step S10, the input signal of the port C is read, and the process proceeds to step S11.
It is detected whether or not is disconnected. Specifically, when the level of the signal input from the port C is fixed and does not change for a certain period of time, it is determined that the wire is disconnected. If the wire is not broken, the process proceeds to step S12 to detect whether or not the engine start permission signal is input to the port C. If the engine start permission signal is input, the engine is allowed to start in step S13, the process proceeds to step S32, the timer is reset, and the process ends. If the engine start permission signal is not input in step S12, the process proceeds to step 14, the engine is prohibited from starting, and the process proceeds to step S32.

If it is determined in step S11 that the port C is disconnected, the process proceeds to step S15, and it is detected whether the flag FLAG2 indicating the disconnection of the port D is set (the flag is set to 1). . Flag FLAG2
If stands, the process proceeds to step S16, and it is detected whether or not the disconnection interval (time from disconnection of port D to disconnection of port C) is short, for example, less than 15 minutes. If it is less than 15 minutes, the process proceeds to step S17, the engine is prohibited, the alarm is sounded to notify theft, the process proceeds to step S32, the timer is reset, and the process ends. It should be noted that the reason for setting 15 minutes is that most of the time, when disconnecting a plurality of communication lines for the purpose of theft, it is generally performed in a short time. If the disconnection interval is 15 minutes or more, the reason is other than theft. This is because it is considered that the wire is broken.

If it is determined in step S16 that the disconnection interval is 15 minutes or more, the engine is allowed to start in step S18, the process proceeds to step S32, the timer is reset, and the process ends. If port D is not disconnected, step S15 is denied and the process proceeds to step S19, where port C
The flag FLAG1 indicating that the wire has been disconnected is set to 1, and the process proceeds to step S20. In step S20, a timer is started to measure the disconnection time interval, and the process proceeds to step S21. In step S21, the input signal of the port D is read, and in step S22, it is detected whether or not the port D is disconnected. If the port D is not broken, the process proceeds to step S23 to detect whether the engine start permission signal is input to the port D. When the engine start permission signal is input, the engine is allowed to start in step S24, the process proceeds to step S32, the timer is reset, and the process ends. If the engine start permission signal is not input, the engine is prohibited from starting in step S25, the process proceeds to step S32, the timer is reset, and the process ends.

If it is determined in step S22 that the port D is disconnected, the flow advances to step S26 to detect whether the flag FLAG1 indicating the disconnection of the port C is set (the flag is set to 1). . If the flag is set, the process proceeds to step S27, and it is detected whether the disconnection interval (the time from the disconnection of port C to the disconnection of port D) is less than 15 minutes. If less than 15 minutes, step S28
In step S32, the engine is prohibited from starting, an alarm is sounded to notify theft, the process proceeds to step S32, the timer is reset, and the process ends. If the disconnection interval is 15 minutes or more in step S27, the process proceeds to step S29, the engine is allowed to start, the process proceeds to step S32, the timer is reset, and the process ends. When it is determined in step S26 that the port C is not disconnected, step S30
And the flag FLAG indicating that the port D is disconnected.
Set 2 to 1 and proceed to step S31. In step S31, a timer is started to measure the time interval of disconnection, and the process ends. According to the above flow chart, when the engine is in the start permission state, the engine is started by setting the key to the start position, but when the engine is in the start prohibition state, the engine is not started even if the key is set in the start position.

When the key 10 is thus set to the IGN-ON position, the CPU of the engine control circuit 3 always checks the signal states of the two ports, so that the communication line of either port is disconnected. However, the engine can be started. Further, since the flag is set in the case of disconnection, the number of disconnected lines can be easily detected, and the time interval in which each communication line is disconnected can be easily measured. Then, it is determined whether the communication line is intentionally disconnected from the length of the disconnection time interval, and if the disconnection time interval is short, it is determined to be disconnection for the purpose of theft and the engine start is prohibited. If it is long, the engine start is permitted as if the engine was disconnected due to a cause other than theft, so that the reliability of the antitheft device can be improved.

In the above embodiment, an example in which two communication lines are connected has been shown, but there may be three or more communication lines. For example, if there are three communication lines, an alarm may be issued to prohibit the engine from starting when two of them are disconnected for a short time, or all three may be connected for a short time. It is also possible to issue an alarm and put the engine in the start prohibited state only when the engine is disconnected. Further, although the short time is set to 15 minutes in the above embodiment, this time may be set by switching with a dip switch or the like. By doing so, it is possible to provide a vehicle anti-theft device that suits the usage condition of the vehicle. Further, when the engine control circuit 3 detects that the communication line is broken, the disconnection may be displayed as a warning at a predetermined location in the driver's seat.

In the key unit of the above embodiment, the key and the lock are magnetically coupled by inserting the key into the lock, and the magnetic information is detected to determine whether or not the correct key is inserted. However, the key unit is not limited to such an electromagnetic type. For example, Japanese Patent Laid-Open No. 2-2078
As disclosed in Japanese Patent Laid-Open No. 1-2003, information is exchanged by optical coupling between a lock having a light emitting portion and a light receiving portion and a key having a built-in light guide member, and the information set in the key is on the lock side. The present invention can be applied by using an optical key unit that permits the engine to start only when the setting information matches.

In the embodiment thus constructed, the key detecting circuit 2 corresponds to the information detecting means and the engine control circuit 3 corresponds to the engine controlling means.

[0020]

As described in detail above, according to the present invention, since a plurality of communication lines are provided between the information detecting means and the engine control means, even if some of the communication lines are disconnected, it continues. Communication can be performed. Therefore, by wiring the plurality of communication lines at different places of the vehicle body, it is possible to effectively prevent disconnection for the purpose of theft. In addition, when multiple communication lines are broken, it is possible to determine whether the broken lines are due to theft by measuring the time interval when each communication line is broken. An antitheft device can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a vehicle antitheft device according to the present invention.

FIG. 2 is a flowchart showing an operation of a key detection circuit of the vehicle antitheft device of FIG.

FIG. 3 is a flowchart showing an operation of an engine control circuit of the vehicle antitheft device of FIG.

FIG. 4 is a configuration diagram of a conventional vehicle antitheft device.

[Explanation of symbols]

 1 key unit 2 key detection circuit 3 engine control circuit

Claims (1)

[Claims] 1. An information detection means for detecting information set in a key and outputting a detection signal, and an engine control means for deciding whether or not to start an engine based on the detection signal sent from the information detection means through a communication line. In an anti-theft device for a vehicle, the information detecting means and the engine control means are connected by a plurality of the communication lines, and the detection signal is received by the engine control means through the plurality of communication lines. The engine control means detects disconnection of two or more communication lines of the plurality of communication lines;
An anti-theft device for a vehicle, comprising: measuring means for measuring a time interval in which each communication line is broken; and prohibiting means for prohibiting engine start when the measured time interval is shorter than a predetermined time. .