JP7146475B2 - Fan heater control circuit - Google Patents

Description

The present invention relates to a fan heater control circuit.

The pot-type liquid fuel fan heater is provided with a fuel pump, a vaporizer, a blower fan, a combustion pot, a fuel heater, and a control circuit (fan heater control circuit) for controlling the electrical configuration. Liquid fuel (hereinafter referred to as petroleum) is introduced into a carburetor by a fuel pump, and vaporized fine particle components of the petroleum vaporized here turn into gaseous fuel and leave the carburetor. This gaseous fuel is mixed with the air introduced by the blower fan and adjusted to a suitable mixture for combustion. This air-fuel mixture is combusted by a fuel-ignited heater located in the combustion kettle.

Also, the control circuit is equipped with a microcomputer and appropriately controls the fuel pump and the blower fan. For this control, an appropriate signal is output from a microcomputer (hereinafter referred to as a microcomputer), and various actuators including a fuel pump actuator (solenoid type plunger drive mechanism) are controlled accordingly. In particular, in Cited Document 1, various signals are input to the microcomputer described above, and the microcomputer collectively executes processing and outputs various control signals.

JP-A-63-116021

However, depending on the malfunction of the microcomputer, there may be a failure mode in which the fuel ignition heater and the fuel pump are driven while the blower motor is turned off. In this case, in the carburetor of the oil fan heater, the oil continues to be drawn and a highly concentrated air-fuel mixture is formed, so in the failure mode where the blower motor is turned off, white smoke is generated from the fan heater. This creates a dangerous situation in which combustible gases continue to leak into the atmosphere.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fan heater control circuit that can avoid white smoke caused by unexpected malfunction of a blower motor.

In order to solve the above problems, the liquid fuel fan heater control circuit of the present invention is configured as follows. That is, a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal, and a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation. a drive permission circuit for outputting a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; and a drive circuit for driving the second actuator based on the drive permission signal. and
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board.
Let the said 1st actuator be the motor for blowers provided in the blower apparatus. The second actuator is a pump actuator provided in a fuel pump device. The first input signal has a pulse waveform corresponding to the cycle of the driving operation when the first actuator is driven.

a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board.
Let the said 1st actuator be the motor for blowers provided in the blower apparatus. The second actuator is a pump actuator provided in a fuel pump device. The first input signal is a signal output from a Hall IC provided in the blower motor.

The first actuator operation detection circuit is wired so as to be interposed between a signal output section of a Hall IC provided in the blower motor and a signal input section of the drive permission circuit.

a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board.
Let the said 1st actuator be the motor for blowers provided in the blower apparatus. The second actuator is a pump actuator provided in a fuel pump device. The drive permitting circuit satisfies both a first condition in which the external command signal has a pulse waveform and a second condition in which the operation confirmation signal indicates that the first actuator is in operation. When the conditions are satisfied, the drive permission signal is output.

a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board.
Let the said 1st actuator be the motor for blowers provided in the blower apparatus. The second actuator is a pump actuator provided in a fuel pump device. The drive permission signal is assumed to have a pulse waveform.

Preferably, the pulse-shaped waveform of the drive enable signal is formed according to the periodic component of the external command signal that is the pulse waveform .

According to the fan heater control circuit of the present invention, a circuit for confirming the operation of the blower motor is provided, and after confirming the operation of the blower motor, the fuel pump is operated. Therefore, in such a control circuit, the fuel pump cannot be driven when only the blower motor fails, so that the generation of dangerous white smoke due to vaporized fuel can be prevented.

Further, even if the microcomputer stops the blower motor due to a runaway operation, or if the blower motor is stopped due to a problem other than the microcomputer, the control circuit can operate the fuel pump based on the driving fact of the blower motor. Driving permission is determined. That is, the control circuit can prevent unnecessary fuel supply to the carburetor system regardless of the failure mode.

2 is a diagram showing the circuit configuration of a fan heater control circuit according to the embodiment; FIG. FIG. 4 is a flow chart showing a pump operation sequence according to the embodiment;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be specifically described with reference to the drawings. A liquid fuel fan heater (hereinafter referred to as a petroleum fan heater) according to the present embodiment is a pot-type combustion device, and as shown in FIG. A control circuit 100 is provided for controlling the device driven by the power generator, the combustion kettle, and other electrical arrangements. It should be noted that there are cases where structural names that are not given reference numerals are not described on the drawings.

The fuel pump P has a sliding mechanism for a plunger, and a solenoid coil is provided so as to surround the housing pipe of the plunger. The plunger is provided with a mechanism for opening the check valve when moving toward the primary side and closing the check valve when moving toward the secondary side when the plunger slides in the housing pipe in the axial direction. . As a result, the plunger continuously discharges a certain amount of fuel oil from the secondary side at the timing of moving from the primary side to the secondary side. Fuel oil is stored on the secondary side and a magnetic body magnetized to a predetermined polarity is arranged in the plunger. This plunger responds to the energization/interruption operation of the solenoid coil to give the fuel oil discharge action. A mechanism composed of a plunger, a magnetic body (permanent magnet, etc.), and a solenoid coil is hereinafter referred to as a second actuator.

The fuel pump P is provided between the fuel tank and the fuel vaporizer 120 via piping. The fuel pump P is driven and controlled by a second actuator, and appropriately adjusts the amount of petroleum supplied from the fuel tank.

The fuel vaporization device has a vaporization sheet at the bottom of the combustion pot, and an appropriate amount of fuel supplied by the fuel pump P is dripped onto this sheet. This vaporization sheet vaporizes the supplied fuel and directs it to the ignition heater 121 .

A bimetal energization switching device 122 (overheat prevention function unit 122) is provided near the combustion pot. The bimetal type energization switching device 122 detects a predetermined temperature and switches energization by a structure in which metals having different temperature characteristics are laminated. The bimetal type energization switching device 122 maintains the energized state when the temperature of the combustion pot is maintained at a temperature in a safe state, and is de-energized when the temperature of the combustion pot deviates from the safe state. That is, the bimetal type energization switching device 122 has a bimetal deformation adapted to the critical temperature of the combustion pot, and cuts off the power supply from the power source Va when the critical temperature is reached.

A blower fan (blower device) functions to guide outside air into the device through a duct in the oil fan heater. The blower fan is axially attached to the shaft of the blower motor Mf (first actuator), and rotates in conjunction with the motor Mf. That is, the blower fan controls the amount of external air supplied according to the operation of the blower motor Mf. This outside air is introduced into a combustion pot, which will be described later, and mixed with the particulate petroleum fuel described above. This air-fuel mixture is adjusted to an air-fuel ratio suitable for combustion, and a combustion state with less NOx or CO is realized.

The combustion pot is provided with an ignition heater 121 in the air-fuel mixture passage, and the heat energy provided by the ignition heater 121 ignites the air-fuel mixture to achieve continuous combustion. The air-fuel mixture that has reached the combustion state reaches complete combustion while passing through the combustion pot, and the surface of the combustion pot radiates a large amount of heat received from the air-fuel mixture to the outside.

As described above, the kerosene fan heater according to the present embodiment includes a fuel supply system (fuel tank → fuel pump → fuel vaporizer), a fuel combustion system (fuel vaporizer → combustion kettle), a ventilation system (duct → fuel vaporizer) → Combustion pot) is systemized, and the entire device provides the heat generated by the combustion of petroleum fuel to the outside of the device.

The fan heater control circuit 100 includes a microcomputer 110, an ignition heater 121, a bimetal energization switching device 122, a command signal detection circuit 150, a blower motor operation detection circuit 170 (first actuator operation detection circuit 170), and a drive circuit. It comprises a permission circuit 130, a drive circuit 180, a blower motor Mf and its Hall IC 160, a fuel pump P and a pump actuator (second actuator).

The functions of the microcomputer 110 will be described in detail later, but the general configuration will be described here for convenience of description. As shown, the microcomputer 110 has a power input port P1, a GND port P2, signal output ports P3 and P6, and signal input ports P5 and P7. Further, the microcomputer 110 includes an arithmetic processing circuit CPU, various conversion circuits AD for performing AD conversion and DA conversion, a memory circuit Me for recording digital information, and a clock circuit (illustrated) for providing clock timing to the bus system. None) etc. are built in.

The microcomputer 110 constructs a desired functional unit and exerts the function by the cooperative functioning of hardware resources and software resources. Specifically, by processing the software written in the memory circuit Me in sequence order, desired result information is created, and if necessary, the information is recorded in the memory circuit Me, or if necessary, it is appropriately recorded. signal. In this operation, the signal input to the microcomputer 110 is applied to the input port and converted into digital information by the AD conversion circuit.

The ignition heater 121 is electrically connected to the output port P3 of the microcomputer 110, and is supplied with an H/L binarized output signal SGh. In the present embodiment, when the output signal SGh is High, current is applied to the ignition heater 121 to apply ignition energy to the vaporized fuel guided from the fuel vaporizer 120 .

In addition, although not shown, a thermistor is arranged in the vicinity of the combustion kettle. The information detected by this thermistor is used by the microcomputer 110 for appropriate processing based on the temperature information.

A signal SGx is input to the input port P5 of the microcomputer 110 via a signal line. At this time, the microcomputer 110 determines whether or not the bimetal energization switching device 122 is actually in the parallel-off state (overheat prevention determination processing S01). When the potential of the signal SGx is in the Low state, the overheat prevention determination process S01 recognizes that the bimetal energization switching device 122 is not energized, and determines that the combustion kettle has reached a dangerous temperature (high temperature). On the other hand, when the potential of the signal SGx is high, the process recognizes that the bimetal energization switching device 122 is energized, and determines that the combustion pot is in a safe temperature range.

When the microcomputer 110 recognizes that the temperature condition of the combustion pot is dangerous, it sets an error flag (S05). This error flag is a flag that defines that even if a retry operation is input, it will be rejected and the operation will not be permitted until the conditions for starting operation are met. The external command signal stop processing S06 does not output the signal SG1 as the external command signal when the error flag is set. In the case of this embodiment, the stoppage of the output of the external command signal means that the waveform of the signal SG1 stabilizes at a constant value, and the output state of the external command signal means that the waveform of the signal SG1 is a periodic waveform (for example, a pulse waveform). ).

A synchronous motor is used as the blower motor Mf, and the rotational position (phase) of the rotor is detected by the Hall IC 160 . The Hall IC 160 outputs a detection signal at an appropriate timing in order to report the rotational position of the stator. That is, when the rotor rotates, the Hall IC 160 outputs a pulse signal according to the operation. This pulse signal is used as the detection signal SG4, and the period of the pulse waveform changes according to the rotational speed.

As shown, the signal output section of the Hall IC 160 is branched from one wiring, one of which is electrically connected to the input port P7 of the microcomputer 110, and the other is electrically connected to the signal input section of the blower operation detection circuit 170. properly connected. Therefore, the detection signal SG4 output from the Hall IC 160 is transmitted to both the input port P7 and the blower operation detection circuit 170. FIG.

The microcomputer 110 determines whether or not the bimetal energization switching device 122 is energized by the signal SGx (process S01), and then detects whether the blower motor Mf has reached a sufficient rotational speed (process S02). . Then, when both of these conditions are met, a periodic pulse-shaped external command signal SG1 is output from the output port P6 (process S03, process S04).

In this embodiment, the output of the pulsed external command signal SG1 is permitted only when the blower motor Mf is rotating. However, in the present embodiment, a blower motor operation detection circuit 170 (first actuator operation detection circuit 170), which will be described later, is provided to determine whether or not the blower motor Mf is rotating. be. In this sense, the blower motor rotation determination on the microcomputer side is positioned as a backup function.

When the command signal detection circuit 150 receives the external command signal SG1, it outputs it as a signal SG2 to the subsequent circuit. That is, it can be said that the external command signal SG1 and the signal SG2 are substantially the same signal. That is, the pulse-like external command signal SG1 is indirectly input as one input to the drive permission circuit 130, which is a subsequent circuit.

In the pump actuator, a drive circuit 180 is connected to a solenoid coil, and sliding control of the plunger is performed by ON/OFF operation of a built-in transistor Tr4. Thereby, the pump actuator adjusts the fuel feed rate per unit time, that is, the flow rate of the fuel in the pipe.

The blower motor operation detection circuit 170, as shown in FIG. 1, comprises a high-pass filter comprising resistors R7 and R9 and a capacitor C1, a rectifying circuit comprising diodes D1 and D2, and a smoothing circuit comprising a resistor R8 and a capacitor C2. . When the signal SG4 is input to the blower motor drive detection circuit 170, the potential state of the point A becomes a steep sawtooth waveform corresponding to the rotation speed of the blower motor Mf. When this electrical state is transferred to point B, the electrical state at point B is a sawtooth wave with the waveform at point A being smoothed and gently decaying. This sawtooth wave (operation confirmation signal SG3) has a waveform with a high level (potential) at the bottom of the waveform when the number of rotations of the blower motor Mf is high, and a low level (potential) at the bottom of the waveform when the number of rotations is low. ). That is, the sawtooth wave shifts upward (high potential) or downward (low potential) as a whole, depending on the number of revolutions of the motor.

In this embodiment, the blower motor is controlled so that the threshold potential of the transistor Tr5 (MOSFET) and the potential of the operation check signal SG3, which corresponds to the minimum allowable number of rotations of the blower motor Mf during pump operation, substantially coincide with each other. The circuit elements of the motion detection circuit 170 are set. Therefore, if the blower motor Mf has not reached the minimum allowable rotational speed, the blower motor operation detection circuit 170 sets the operation confirmation signal SG3 to a low potential, and at this time the transistor Tr5 is in a non-energized state. On the other hand, if the blower motor Mf has reached the minimum allowable number of rotations, the operation confirmation signal SG3 is set to a high potential enough to form a gate channel, and at this time the transistor Tr5 is energized.

The drive permission circuit 130 is composed of transistors Tr2, Tr3, Tr5, and resistor elements R1 to R4. Among them, the transistor Tr5 is an n-channel MOSFET, and the other transistors are pnp type bipolar transistors. The transistor Tr2 has an emitter connected to the bimetal energization switching device 122, and a voltage dividing point of the resistance elements R1 and R2 connected to the base. The common contact of the resistor element R3 and the emitter of the transistor Tr3 is connected to the collector of the transistor Tr2. be done. The transistor Tr5 has a drain connected to the resistance element R4 and a source connected to GND.

When the external command signal SG1 (pulse wave) is given from the output port P6 of the microcomputer, the drive permission circuit 130 causes the transistor Tr2 to change the waveform of the external command signal SG1 if the potential of the subsequent stage of its collector is lowered. Repeat the energization/interruption in the reversed state. At this time, the transistor Tr3 outputs a pulse waveform according to the operation of the transistor Tr2. Hereinafter, the signal in this waveform state will be referred to as drive permission signal SG5.

In the description so far, it is assumed that the potential of the post-collector stage of the transistor Tr2 is low. In this case, in a safe situation where the overheat prevention function does not work, a signal (drive enable signal SG5) obtained by inverting the pulse waveform of the external command signal SG1 is output from the collector terminal of the transistor Tr3. On the other hand, in a dangerous situation where the overheat prevention function is activated, the transistors Tr2 and Tr3 are switched to the non-energized state, and the drive permission signal SG5 is not output.

However, the drive permission circuit 130 is provided with another condition that defines the output of the drive permission signal SG5. The condition is given by the operating state of the blower motor operation detection circuit 170 . More specifically, in the blower motor operation detection circuit 170, as described above, when the blower motor Mf reaches a predetermined number of rotations, the potential difference between the gate and the source of the transistor Tr5 increases, and Tr5 is turned on. It is said that In this situation, if the pulse-shaped signal SG2 is input to the blower motor operation detection circuit 170, the drive enable signal SG5 also becomes an intermittent output current in response to this.

On the other hand, in the blower motor operation detection circuit 170, when the blower motor Mf is less than the predetermined rotational speed, the potential difference between the gate and the source of the transistor Tr5 decreases, and the transistor Tr5 returns to the non-energized state. In this situation, the blower motor operation detection circuit 170 does not output the drive enable signal SG5 even if the pulse signal SG2 is input, because the transistor Tr3 is rendered non-conductive.

That is, the drive permission circuit 130 outputs the drive permission signal SG5 based on the signal states of both the external command signal SG1 (SG2) and the operation confirmation signal SG3. Specifically, the drive permission circuit 130 outputs the drive permission signal SG5 only when the overheat prevention function is in a safe state and the blower motor Mf is operating at a predetermined number of revolutions or higher. output. In other words, the drive permission circuit 130 outputs the drive permission signal SG5 according to the AND condition of the external command signal SG1 and the operation confirmation signal SG3.

A drive circuit 180 provided at the subsequent stage is composed of a transistor Tr4, a resistance element R5 provided at the base of the transistor Tr4, and a resistance element R6 provided between the base and the emitter. The drive circuit 180 remains in a non-conducting state because the base-emitter is not energized unless the drive enable signal SG5 is input to the transistor Tr4. On the other hand, when the drive enable signal SG5 is input to the base of the transistor Tr4, the energization between the base and the emitter is intermittently performed, and a conductive state is formed accordingly.

Thus, when the drive permission signal SG5 is input, the transistor Tr4 performs the piston operation of the pump actuator accordingly. In the pump actuator, the plunger is driven according to the energization operation of the transistor Tr4, thereby realizing the fuel supply operation. That is, unless both the external command signal SG1 (SG2) and the operation confirmation signal SG3 meet the predetermined conditions, the drive permission signal SG5 is not output. Therefore, in the control circuit 100 according to the present embodiment, when only the blower motor Mf fails and stops, the fuel pump P cannot be driven, so that the generation of dangerous white smoke due to vaporized fuel can be prevented. .

In the circuit configuration described above, the blower motor operation detection circuit 170 is external to the microcomputer 110, and is appropriately mounted on the circuit board. A signal SG4 indicating the operation of the blower motor Mf is sent directly to the blower motor operation detection circuit 170 without going through the microcomputer 110 . Therefore, even if the microcomputer 110 stops the blower motor due to a runaway operation, or if the blower motor Mf is stopped due to a problem other than the microcomputer, the control circuit 100 can control the operation of the blower motor Mf based on the fact that the blower motor Mf is driven. Fuel pump operation is permitted. That is, the control circuit can ensure the safety of the evaporator system regardless of the failure mode.

100 liquid fuel fan heater control circuit (control circuit), 110 microcomputer (microcomputer), 121 ignition heater, 122 bimetal energization switching device (overheat prevention function unit), 130 drive permission circuit, 150 command signal detection circuit, 160 hall IC , 170 blower motor operation detection circuit (first actuator operation detection circuit), 180 drive circuit, Mf blower motor, P fuel pump.

Claims (6)

a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board ,
The first actuator is a blower motor provided in a blower device,
The second actuator is a pump actuator provided in a fuel pump device,
A fan heater control circuit according to claim 1, wherein said first input signal has a pulse waveform corresponding to a period of said driving operation when said first actuator is being driven . a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board,
The first actuator is a blower motor provided in a blower device,
The second actuator is a pump actuator provided in a fuel pump device ,
A fan heater control circuit, wherein the first input signal is a signal output from a Hall IC provided in the blower motor. a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board,
The first actuator is a blower motor provided in a blower device,
The second actuator is a pump actuator provided in a fuel pump device ,
The drive permitting circuit satisfies both a first condition in which the external command signal has a pulse waveform and a second condition in which the operation confirmation signal indicates that the first actuator is in operation. A fan heater control circuit that outputs the drive permission signal when the conditions are satisfied. a microcomputer that outputs an external command signal based on the states of both the first input signal and the second input signal; a first actuator operation detection circuit that outputs an operation confirmation signal when the first actuator is in operation; a drive permission circuit that outputs a drive permission signal for the second actuator based on the signal states of both the external command signal and the operation confirmation signal; a drive circuit that operates the second actuator based on the drive permission signal; with
The first actuator operation detection circuit is provided outside the microcomputer and mounted on a circuit board,
The first actuator is a blower motor provided in a blower device,
The second actuator is a pump actuator provided in a fuel pump device ,
The fan heater control circuit, wherein the drive enable signal has a pulse waveform. The first actuator operation detection circuit is wired so as to be interposed between a signal output section of a Hall IC provided in the blower motor and a signal input section of the drive permission circuit. 3. The fan heater control circuit according to claim 1 or 2 . 5. The fan heater control circuit according to claim 4, wherein the pulse-like waveform of said drive enable signal is formed according to the periodic component of said external command signal which is made into a pulse waveform .

Images