JPH0222573A - Load controller equipped with self-diagnosing function - Google Patents

Abstract

PURPOSE:To obtain the small-sized load controller with superior reliability by turning off the power source automatically in the case of short-circuiting and securely preventing the normally open state of a solenoid valve. CONSTITUTION:A power transistor (TR) 18 drives the solenoid valve 13 and a Hall element (detecting means) 15 detects an exciting current which flows to the solenoid valve 3. The 1st control means of a control circuit 2 outputs an operation signals SG1 for turning on the TR 18 and a diagnostic signal SG2 for turning off the TR 18 momentarily at constant intervals of time. A decision means (AND circuit) 22 decides the short-circuit state of the TR 18 according to the output signal of the TR 18, the operation signal SG1, and diagnostic signal SG2. The 2nd control means of the control circuit 2 turns off the power source of the TR 18 according to the output of the decision means 22. Consequently, while a load is driven, the occurrence state of the short-circuiting and breakage of an output element such as the TR 18, the wire breaking of a circuit, etc., is detected.

Description

[Detailed Description of the Invention] Purpose of the Invention [Field of Industrial Application] 1. The present invention is capable of detecting the presence or absence of failures such as short circuits or damage to output elements such as power transistors, or disconnection of circuits while driving a load. The present invention relates to a load control device.

[Prior Art] Conventionally, solenoid valves that open and close fuel gas in gas appliances such as water heaters and boilers are driven based on the main drive current from a load III control device. In such a load control device, when a power transistor is used as a driving element of a solenoid valve, the power transistor is destroyed by heat or external surge and becomes constantly in a conductive state or in a non-conductive state, resulting in a lack of reliability. In particular, if the electromagnetic valve is always in the conductive state and the solenoid valve is always in the open state, there is a risk that a gas leakage accident will occur. Therefore, we used a contact relay that is unlikely to be constantly conductive to connect the solenoid valve to 1Flr.
It has also been proposed to do n.

[Problem to be Solved by the Invention 1] However, when the above-mentioned contact relay is used, the load 1i11 control device becomes large and the life of the contact of the contact relay is short. There was a problem in that it needed to be replaced every period. The purpose of this invention is to improve reliability by using a power transistor as an output element to drive a load such as a solenoid valve, and by automatically cutting off the power supply when the transistor is short-circuited and reliably preventing the solenoid valve from being constantly open. The object of the present invention is to provide an excellent and compact load control device.

Structure of the Invention [Means for Solving the Problems 1] In order to solve the above-mentioned problems, the present invention provides i! A power transistor that drives a solenoid valve, a detection means that detects an excitation current flowing through the solenoid valve, an operation signal that turns on the power transistor, and a diagnostic signal that turns off the power transistor momentarily at regular intervals. a first control means for outputting a first control means; a determination means for determining a short-circuit state of the power transistor based on the output signal of the detection means, an operation signal, and a diagnostic signal; and a determination means for determining the short circuit state of the power transistor based on the output of the determination means and a second control means for shutting off.

[Operation] When a short-circuit state of the power transistor is detected by the above means based on the output signal, operation signal, and diagnostic signal of the detection means, the power to the power transistor is cut off, and the MF
The drive of valve 41 is stopped.

[Embodiment] Hereinafter, an example of an actual Ih embodying the present invention will be described with reference to the drawings.The load control device 1 shown in FIG. It is possible to drive a gas opening/closing solenoid valve 3 connected as a load. The electromagnetic valve 3 will be explained according to FIG. 2. A gas communication hole 5 is formed in the main body 4. A core 6 is fixed to the upper part of the main body 4, and a plunger 7 is attached to the core 6.
is supported to be movable up and down, and a spring receiver 8 and a valve seat 9 are fitted to the lower end of the plunger 7.

A return spring 10 is disposed between the spring receiver 8 and the core 6, and its urging force normally causes the plunger 7 to descend and the valve seat 9 to close the communication hole 5.

A coil 11 is disposed around the plunger 7, and when an excitation current is supplied through a power line 12 connected to the control circuit 2, the coil 11 is excited and the plunger 7 is pulled upward. Therefore, when the coil 11 is excited, the valve seat 9 is moved upward as the plunger 7 is moved, so that the communication hole 5 is opened.

A magnetic core 13 is fitted onto the core 6 above the plunger 7. An auxiliary core 14 is attached to the upper part of the core 6, and a Hall element 15 is attached between the auxiliary core 14 and the magnetic core 13. The power line 12 is branched and connected to the Hall element 15 to supply power, and a signal line 16 is also connected thereto. When the coil 11 is excited while power is being supplied to the Hall element 15 and the magnetic flux generated in the coil 11 is shunted from the auxiliary core 74 to the magnetic core 13, a voltage corresponding to the magnetic flux density is applied from the Hall element 15. The signal line 16 is output in red.

The power supply line 17 of the load control device 1 has a power supply voltage VC.
C is supplied, and its power supply line 17 and load control! 4 stomachs 1
The coil 11 is connected in series via a power supply line 12 to the collector terminal of a power transistor 18 constituting the final output stage. The emitter terminal of the power transistor 18 is grounded, and the base terminal is connected to the control circuit 2 via a resistor R1, and receives the input signal SG1 shown in FIG. 3(a).

The collector terminal of a diagnostic transistor 19 for outputting a pulse signal for failure diagnosis to the base terminal of the power transistor 18 is connected to the base terminal of the power transistor 18, and the emitter terminal of the diagnostic transistor 19 is grounded. The base terminal is connected to the control circuit 2 via a resistor R2. The control circuit 2 outputs a diagnostic signal SG2 to the diagnostic transistor 19 in the form of a pulse signal with a constant period as shown in FIG. 3(b).

The signal line 16 of the Hall element 15 is connected to an amplifier 20 in the load control device 1, and the output signal of the Hall element 15 is amplified by the amplifier 20, and the output signal of the amplifier 20 is connected to the non-inverting input terminal of the comparator 21. is output to. The inverting input terminal of the comparator 21 has a base tI! set in advance by resistors R3 and R4 and a variable resistor VR. Voltage is being input. Therefore, when the output voltage of the amplifier 20 becomes higher than the base Q' lightning voltage, that is, when the power transistor 18 is turned on and the coil 11 is excited,
Outputs the torque signal. The output signal of the comparator 21 is output to the first AND circuit 22 and also to the second AND circuit 24 via the inversion circuit 23.

The operating signal SG1 outputted from the control circuit 2 to the power transistor 18 is also outputted to the first and second AND circuits 22.24, and the diagnostic signal SG2 outputted to the diagnostic transistor 19 is outputted to the first AND circuit 22. At the same time, it is outputted to the second AND circuit 24 via the inversion circuit 25. In addition, the first and second AND circuits 22 and 24
The output signal of each is outputted to each self-holding circuit 26.27, and each self-holding circuit 26.27 is outputted to each AND circuit 22.27.
After the torque output signal is output from the controller 24, the torque output signal continues to be output to the control circuit 2.

The control circuit 2 includes at least one self-holding circuit 2.
6.27) - When the signal of the 1-level signal is output, the supply of power to the power supply line 17 is stopped.

Next, the operation of the load control device 1 configured as described above will be explained.

Now, when the control circuit 2 outputs the operation signal SG1 shown in FIG. 3(a) to the power transistor 18 of the load control device 1, the power transistor 18 is turned on and the solenoid valve 3
An excitation current flows through the coil 11, and the plunger Y is moved upward to open the communication hole 5. When the coil 11 is excited, the Hall probe 15 outputs a signal voltage, and the comparator 21 outputs a trubel signal based on the signal voltage.

When the diagnostic signal SG2 shown in FIG. 3(b) is output from the control circuit 2 together with the operating signal SG1 at regular intervals, the diagnostic transistor 19 is turned on at regular intervals. When the diagnostic transistor 19 is turned on, the base voltage of the power transistor 18 decreases, so the power transistor 18 is temporarily turned off, and at this time the coil 11
Since no excitation current flows through , the output signal of the comparator 21 becomes L-level. Therefore, the output signal of the comparator 21 becomes the output signal SG3 which has the opposite phase to the diagnostic signal SG2 as shown in FIG. Since at least one of the 22 input signals becomes a trubel, 11
The output signal of the -th AN1) circuit 22 never becomes a torque level. Similarly, when the power transistor 18 is operating normally, at least one of the input signals of the second AND circuit 24 becomes a torque signal, so the second
The output signal of the D circuit 24 never becomes a torque level.

On the other hand, if the power transistor 18 is short-circuited,
Even when the diagnostic signal SG2 is output and the diagnostic transistor 19 is turned on, the collector current continues to flow through the power transistor 18 and the coil 11 continues to be excited. 21 output signal S
G3 continues to be in the torque state even if the diagnostic signal SG2 is in the torque state. Then, since all the input signals of the first AND circuit 22 become torubel, the output signal SG4 of the first AND circuit 22 becomes torubel as shown in FIG. 3(C). Then, based on the output signal SG4, the self-holding circuit 26 outputs the output signal SG5 shown in FIG. 3(e) to the control circuit 2, and the control circuit 2 outputs the output signal SG5.
The power supply voltage VCC is cut off based on this. Therefore, when the power transistor 18 is short-circuited, the power supply voltage vCC of the load control device 1 is automatically cut off by the control circuit 2. Therefore, even when the power transistor 18 is short-circuited, the excitation current does not continue to flow through the coil 11. do not have.

Furthermore, if the power transistor 18 becomes unable to conduct or a disconnection occurs in the load control device 1, even if the operating signal SG1 is at the 1'' level and the diagnostic signal SG2 is at the L level, as shown in FIG. Since the output signal SG3 of the comparator 21 becomes L level as shown in FIG. The output signal SG6 of the circuit 24 is []
level. Then, based on the output signal SG6, the self-holding circuit 27 outputs an output signal SG7 at the level T().

As described above, in this load control device 1, when the power transistor 18 is short-circuited, the control circuit 2 automatically cuts off the power supply voltage VCC. This prevents problems such as gas leakage from occurring even when the solenoid valve 3 is used as an on-off valve in a gas combustion system. Also, when the power transistor 18 becomes unable to conduct, or when a disconnection occurs in the load control device 1, the power supply voltage VCC is cut off, and the solenoid valve 3
operation is stopped.

Therefore, while this load control device 1 uses the power transistor 18 as an output element for driving the solenoid valve 3, it can automatically cut off the power supply in the event of a failure to prevent the solenoid valve 3 from malfunctioning.

Effects of the Invention As detailed above, the present invention uses a power transistor as an output element to drive a load such as a solenoid valve, and when the transistor is short-circuited, the power is automatically cut off to ensure that the solenoid valve is always open. By preventing this, it is possible to provide an excellent effect of providing a highly reliable and compact load control tiIl device.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a load control S1 position embodying the present invention, Fig. 2 is a sectional view showing a solenoid valve, and Figs. 3 and 4 are timing charts showing the operation of the load control device. .

Claims (1)

[Claims] 1. A power transistor (18) that drives a solenoid valve (3).
), a detection means (15) for detecting the excitation current flowing through the solenoid valve (3), an operation signal (SG1) for turning on the power transistor (18), and a detection means (15) for detecting the excitation current flowing through the solenoid valve (3);
) is turned off momentarily at regular intervals (SG2
); and an output signal of the detection means (15) and an operation signal (SG1).
and the power transistor (
18); and a second control means (2) for cutting off the power to the power transistor (18) based on the output of the determining means (22). Load control device with functions.