JP2003157101A - Load controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load controller which prevents malfunction due to a drop in source voltage. SOLUTION: The load controller is equipped with a plurality of loads 8 and 11, a plurality of instruction input means 3 and 7 which each instruct the driving of a specified plurality of loads between the plurality of loads 8 and 11, a control means 2 which reads in instruction input from the plurality of instruction input means 3 and 7 and drives the corresponding loads 8 and 11, and monitor means 2 and 12 which monitor the state of a source voltage. When the monitor means 2 and 12 detect an abnormal drop of the source voltage during the driving of the specified load 8 corresponding to the specified instruction input means 3 according to the instruction input from the specified instruction input means 3 between the instruction input means, the control means 2 holds keeps on reading in the instruction input from the specified instruction input means 3 and switches the driving of the load 11 other than the load 8 corresponding to the specified instruction input means 3 to the safe side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device, and more particularly to fail-safe control of a load against erroneous reading of an input switch when a power supply voltage drops.

[0002]

2. Description of the Related Art FIG. 3 is a circuit diagram showing an example of a conventional load control device. In FIG. 3, an ECU (electronic control unit) 1 has a communication function for controlling a load such as a starter motor in an automatic vehicle, for example.

The ECU 1 has a built-in CPU (central processing unit). At the input port P1 of the CPU2,
A reverse switch 3 which is one of shift switches of an automatic transmission connected to a battery power source + B is connected via a voltage dividing circuit of resistors 4, 5 and 6, and a starter motor drive request signal is communicated to an input port P2. The communication unit 7 is connected via a communication interface (I / F) circuit 14. Note that C
A shift switch other than the reverse switch 3 is connected to the PU 2, but it is not shown here.

A solenoid 8 is connected to an output port P4 of the CPU 2 via an output interface (I / F) circuit 13, and a base of a switching transistor 9 is connected to the output port P5. The emitter of the switching transistor 9 is grounded, and the collector is connected to the battery power source + B via the exciting coil 10a of the relay 10.
It is connected to the. The relay contact 10b of the relay 10 is
One end is connected to the battery power source + B, and the other end is grounded via the starter motor 11.

In the above configuration, the reverse switch 3
Is turned on, a high-level signal is input to the input port P1, so that the CPU 2 reads that there is a reverse drive instruction input, and outputs the output interface (I / F) circuit 13 from the output port P4. Through
A high-level drive signal is output to drive the solenoid 8 and the transmission is switched to reverse.

A starter motor drive request signal is sent from the communication unit 7 to the communication interface (I / F) circuit 1.
When it is input to the input port P2 via
Controls to output a high level drive signal from the output port P5, whereby the switching transistor 9 is turned on, a current flows from the battery power source + B to the exciting coil 10a of the relay 10, and the relay contact 10b is turned on. Then, current flows from the battery power source + B to the starter motor 11 via the relay contact 10b, and the starter motor 1
1 is driven.

While the reverse switch 3 is on, C
Even if the starter motor drive request signal from the communication unit 7 is input to the input port P2 via the communication interface (I / F) circuit 14, the PU2 prohibits the output signal P5 from outputting a high level drive signal. , Control to prevent dangerous operating conditions.

[0008]

In the load control device having the above-described configuration, whether the input switch, that is, the reverse switch 3 is on or off (that is, whether it is at a high level) regardless of the state of the power source voltage of the battery power source + B. Reading low level). In this case, as shown in FIG. 4, if the power supply voltage of the battery power supply + B drops below the erroneous reading occurrence level Vth of the CPU 2 for some reason, even if the reverse switch 3 is turned on,
Since the input voltage of the input port P1 decreases as the power supply voltage decreases, the CPU 2 recognizes the high level of the reverse switch 3 in the period A until the power supply voltage reaches the erroneous reading occurrence level Vth. In the period B when the voltage becomes equal to or lower than the erroneous reading occurrence level Vth, the reverse switch 3 may not be recognized as ON (high level) and may be erroneously recognized as OFF (low level).

Then, the CPU 2 uses the reverse switch 3
When the starter motor drive request signal is input from the communication unit 7 to the input port P2 in the state in which it is erroneously recognized that the switch is on the off (low level) side, an on (high level) drive signal is output to the output port P5. There is a malfunction that the output is made and the starter motor 11 is driven. That is, there is a danger that the starter motor will be driven when the transmission is in reverse.

In view of the above-mentioned conventional problems, an object of the present invention is to provide a load control device which prevents malfunction due to a decrease in power supply voltage.

[0011]

The invention according to claim 1 made in order to solve the above-mentioned problems, includes a plurality of loads, and a plurality of instructions for instructing driving of a specific load among the plurality of loads. The input means, the control means for reading the instruction input from the plurality of instruction input means, and controlling so as to drive the corresponding load, the monitoring means for monitoring the state of the power supply voltage, the control means, Based on an instruction input by a specific instruction input means of the instruction input means, while the specific load corresponding to the specific instruction input means is being driven, it is detected by the monitoring means that the power supply voltage has abnormally dropped. In this case, the control means keeps reading the instruction input from the specific instruction input means and switches the driving of loads other than the load corresponding to the specific instruction input means to the safe side. Gosuru it consists in a load control device according to claim.

According to another aspect of the present invention, the load control device includes a plurality of loads, a plurality of instruction input means for instructing driving of a specific load among the plurality of loads, and a plurality of instruction input means. Of the instruction input, and a control means for controlling to drive the corresponding load, a monitoring means for monitoring the state of the power supply voltage, and a control means for instructing by a specific instruction input means of the plurality of instruction input means. When the monitoring means detects that the power supply voltage has abnormally dropped while driving the specific load corresponding to the specific instruction input means based on the input, the control means instructs the specific instruction input means. The reading of the input is held and the driving of loads other than the load corresponding to the specific instruction input means is controlled to be switched to the safe side.

As a result, when the power supply voltage is abnormally lowered, the fail-safe control is performed in the switch state on the safe side set by the system to prevent a dangerous malfunction.
The adverse effect on the user can be reduced.

The present invention as set forth in claim 2 made in order to solve the above-mentioned problems, is present in the load control device as set forth in claim 1, characterized in that the instruction input means includes a high-side or low-side input switch. .

According to another aspect of the invention, the instruction input means includes a high side or low side input switch. Accordingly, it is possible to prevent the ON state of the high-side or low-side input switch from being erroneously read as the OFF state or the OFF state from being erroneously read as the ON state.

The invention according to claim 3 made to solve the above-mentioned problems resides in the load control device according to claim 1, characterized in that the instruction input means includes a communication unit.

According to another aspect of the invention, the instruction input means includes a communication unit.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a load control device according to the present invention. In FIG. 1, E
The CU (electronic control unit) 1 has a communication function for controlling a load such as a starter motor in an automatic vehicle, for example.

The ECU 1 has a built-in CPU (central processing unit) 2 as a control means. A reverse switch 3 as one of instruction input means, which is a high side input switch connected to a battery power source + B, is connected to an input port P1 of the CPU 2 through a voltage dividing circuit of resistors 4, 5 and 6. A communication unit 7 as another instruction input unit for communicating a starter motor drive request signal is connected to the input port P2 via a communication interface (I / F) circuit 14. The CPU 2
Although a shift switch other than the reverse switch 3 is also connected as another instruction input means, it is not shown here.

Further, the input port P3 of the CPU 2 has
A power supply voltage input interface (I / F) circuit 12 connected to the battery power supply + B and acting as part of the monitoring means.
Are connected. At the input port P6, the CPU 2 receives the input voltage from the power supply voltage input I / F circuit 12 as A /
By detecting as a digital value via a D conversion unit (not shown), it functions as a part of the monitoring means and measures / monitors the power supply voltage of the battery power supply + B.

Further, the solenoid 8 is connected to the output port P4 of the CPU 2 through the output interface (I / F) circuit 13, and the base of the switching transistor 9 is connected to the output port P5. The emitter of the switching transistor 9 is grounded, and the collector is connected to the battery power source + B via the exciting coil 10a of the relay 10.
It is connected to the. The relay contact 10b of the relay 10 is
One end is connected to the battery power source + B, and the other end is grounded via the starter motor 11.

In the above structure, when it is detected that the power supply voltage of the battery power supply + B is not lowered at the input port P3, the normal operation is performed as follows.

That is, when the reverse switch 3 is turned on, a high level signal is input to the input port P1, so that the CPU 2 reads that there is a reverse drive instruction input and outputs it from the output port P4. A high-level drive signal is output via the interface (I / F) circuit 13 to drive the solenoid 8 to switch the transmission to the reverse.

Further, the starter motor drive request signal is sent from the communication unit 7 to the communication interface (I / F) circuit 1.
When it is input to the input port P2 via
Controls to output a high level drive signal from the output port P5, whereby the switching transistor 9 is turned on, a current flows from the battery power source + B to the exciting coil 10a of the relay 10, and the relay contact 10b is turned on. Then, current flows from the battery power source + B to the starter motor 11 via the relay contact 10b, and the starter motor 1
1 is driven.

While the reverse switch 3 is on, C
Even if the starter motor drive request signal from the communication unit 7 is input to the input port P2 via the communication interface (I / F) circuit 14, the PU2 prohibits the output signal P5 from outputting a high level drive signal. , Control to prevent dangerous operating conditions.

On the other hand, if it is detected at the input port P3 that the power source voltage of the battery power source + B has dropped abnormally, the fail safe operation is performed as follows.

That is, as shown in FIG. 2, when the power source voltage of the battery power source + B drops below the erroneous reading occurrence level Vth of the CPU 2 for some reason while the reverse switch 3 is on, the CPU 2 determines that the input port The digital value obtained by A / D converting the input voltage from the power supply voltage input I / F circuit 12 at P3 detects that the power supply voltage has abnormally dropped below the erroneous reading occurrence level.

The power source voltage of the battery power source + B is
Occurrence level V of erroneous reading of CPU 2 for some reason
When the voltage is abnormally decreased to th or less, even if the reverse switch 3 is turned on, the input voltage of the input port P1 decreases with the decrease of the power supply voltage, but the CPU 2 detects the abnormal decrease of the power supply voltage at the input port P3. Based on the detection, an internal process is performed so that the input read at the input port P1 is held in the read state immediately before the detection.

Therefore, the CPU 2 has a period A until the power source voltage reaches the erroneous reading occurrence level Vth and a period B when the power source voltage becomes the erroneous reading occurrence level Vth or less.
Also continues to hold the read (high level) reading of the reverse switch 3, and in this state, the starter motor drive request signal is input from the communication unit 7 to the input port P2 via the communication interface (I / F) circuit 14. Even if it is done, the CPU 2 prohibits the output signal of ON (high level) from being output to the output port P5 and keeps it OFF (low level).

As described above, when the CPU 2 has a voltage equal to or lower than the power supply voltage at which the input switch is erroneously read, the read value is not used for control, and fail-safe control is performed with the switch state on the safe side set by the system. As a result, it is possible to prevent dangerous malfunctions and reduce adverse effects on the user.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications and applications are possible.

For example, in the above-mentioned embodiment, the high side input switch is used as the instruction input means, but the low side input switch may be used.

Further, in the above-mentioned embodiment, at the output port P5, when the abnormality of the power supply voltage is detected, the fail-safe control is performed so as to change from the off (low level) state before the detection to the off (low level) state after the detection. Although it is switched to the safe side by doing, depending on the type of load to be driven, it will be from the off (low level) state before detection to the on (high level) state after detection, or the on (high level) state before detection. It is also possible to perform fail-safe control from ON to the ON (high level) state after detection, or from the ON (high level) state before detection to the OFF (low level) state after detection.

[0034]

According to the first aspect of the present invention, when the power supply voltage is abnormally lowered, fail-safe control is performed in the switch state on the safe side set by the system, thereby preventing a dangerous malfunction and preventing the user from operating the switch. Can be less adversely affected.

According to the second aspect of the present invention, it is possible to prevent the ON state of the high-side or low-side input switch from being erroneously read as an OFF state or the OFF state from being erroneously read as an ON state.

The instruction input means may include a communication unit as in the invention of claim 3.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a load control device according to the present invention.

FIG. 2 is a signal timing chart of each unit in the load control device of FIG.

FIG. 3 is a circuit diagram showing an example of a conventional load control device.

FIG. 4 is a signal timing chart of each unit in the load control device of FIG.

[Explanation of symbols]

1 ECU 2 CPU (control means; part of monitoring means) 3 Reverse switch (instruction input means) 7 Communication unit (instruction input means) 8 solenoids (load) 9 switching transistors 10 relays 11 Starter motor (load) 12 Power supply voltage input I / F circuit (part of monitoring means) 13 Output interface (I / F) circuit 14 Communication interface (I / F) circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H209 AA10 BB18 CC09 CC11 DD14                       GG14 HH04                 5K048 AA09 BA42 EB02 FC01 GA09                       HA34

Claims (3)

[Claims] 1. A plurality of loads, a plurality of instruction input means for instructing driving of a specific load among the plurality of loads, and an instruction input from the plurality of instruction input means, and reading the corresponding loads. Control means for controlling to drive, monitoring means for monitoring the state of the power supply voltage, and the control means, based on an instruction input by a specific instruction input means of the plurality of instruction input means, the specific instruction When the monitoring means detects that the power supply voltage has abnormally dropped while driving a specific load corresponding to the input means, the control means reads the instruction input from the specific instruction input means. A load control device, which holds and controls so that driving of loads other than the load corresponding to the specific instruction input means is switched to a safe side. 2. The load control device according to claim 1, wherein the instruction input means includes a high side or low side input switch. 3. The load control device according to claim 1, wherein the instruction input means includes a communication unit.