JPH01319811A - Proportionate valve driving circuit - Google Patents

Abstract

PURPOSE:To improve the opening characteristic of a proportionate valve and to reduce the energy consumption of a conducting element by energizing a proportionate control valve with the output amplitude-modulated to the oscillation frequency of an oscillating circuit formed by a positive feedback circuit. CONSTITUTION:The control voltage from a microcomputer inputted from a terminal 64 is inputted to a positive input terminal 61a of an operational amplifier 61a by a proportionate valve circuit 60. To a negative input terminal 61b of the operational amplifier 61, the voltage of a connecting point 69 is negative- fed back by a conductor 70, further, the voltage of the connecting point 69 is differentiated and positive-fed back by a capacitor 68 to the positive input terminal 61a and by the proportionate valve circuit 60, an oscillating circuit is formed and oscillation is executed. Consequently, the output voltage in accordance with the control voltage from the microcomputer is amplitude-modulated by the formed oscillating circuit and the amplitude-modulated current is supplied at a proportionate valve 23. Thus, the opening characteristic can be improved and the electric power for energizing can be reduced.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is used to adjust the amount of fluid passing through, and drives a proportional control valve whose opening degree corresponds to an energized current in accordance with a control voltage. This invention relates to a proportional valve drive circuit.

[Prior Art] For example, in a combustion device, a proportional control valve that adjusts the amount of fuel supplied to a burner is energized by a drive circuit that outputs a direct current according to a control voltage from a control circuit, and the valve body receives the current. The opening degree corresponds to the value.

In this case, the force for driving the valve body and adjusting the flow rate of the fluid is generated against the pressure exerted on the valve body by the passing fluid, and the valve body is supported by an elastic body such as rubber. .

[Problem to be solved by the invention] For this reason, even if the same current value is given when the opening of the proportional valve is changed and made larger, and when the opening is changed and made smaller, the proportional There are differences in the degree of opening exhibited by the valves. Therefore, the secondary pressure regulated by the proportional valve will have hysteresis characteristics as shown in FIG.
There is a problem in that the flow rate of the passing fluid cannot be accurately obtained. Further, since direct current proportional to the control voltage is constantly applied to the proportional valve, there is a problem in that the energizing circuit of the proportional valve consumes a lot of power and the energizing element generates a large amount of heat.

An object of the present invention is to reduce the hysteresis characteristic of a proportional valve to improve its opening degree characteristic, and to reduce the power consumption of an energizing element that energizes the proportional valve to suppress the amount of heat generated.

[Means for Solving the Problems] The present invention provides a proportional valve drive circuit that drives a proportional control valve whose opening degree corresponds to an energized current in accordance with a control voltage. Equipped with a negative input terminal,
a differential amplifier circuit that outputs a voltage according to the voltage difference between the positive input terminal and the negative input terminal; and a proportional valve energization circuit that energizes the proportional control valve with a current that corresponds to the output voltage of the differential amplifier circuit. a voltage drop detection means for detecting a voltage drop due to the proportional control valve; a negative feedback circuit that negatively feeds back the voltage drop to the negative input terminal; and a negative feedback circuit that differentiates the voltage drop and feeds it back positively to the positive input terminal. The technical means is to provide a positive feedback circuit.

[Operation] In the proportional valve drive circuit of the present invention, when the control voltage is input to the positive input terminal of the differential amplifier circuit, the differential amplifier circuit outputs a voltage according to the voltage difference with the negative input terminal. In the proportional valve energizing circuit, the proportional control valve is energized with a current value that corresponds to the output voltage of the differential amplifier circuit.

A voltage drop due to the proportional control valve when the proportional control valve is energized is detected by the voltage drop detection means, and the voltage drop is negatively fed back to the negative input terminal of the differential amplifier circuit by the negative feedback circuit. Further, the voltage drop is differentiated by a positive feedback circuit and positively fed back to the positive input terminal, and the differentiated voltage drop is added to the control voltage. Then, in the differential amplifier circuit, an oscillation circuit is formed by the positive feedback circuit. Therefore, the output voltage differentially amplified according to the voltage difference between the control voltage and the dropped voltage is amplitude-modulated to the oscillation frequency of the formed oscillation circuit and output to the proportional valve energization circuit.

The proportional control valve is energized by the proportional valve energization circuit in accordance with the output voltage amplitude modulated by the differential amplifier circuit.

[Effects of the Invention] In the present invention, the proportional control valve is energized with an output that is amplitude-modulated to the oscillation frequency of the oscillation circuit formed by the positive feedback circuit. At this time, the valve body of the proportional control valve cannot follow changes in the applied current due to its mechanical structure, and vibrates with a minute amplitude. Furthermore, the proportional control valve exhibits an opening degree that corresponds to the effective value of the supplied current. Therefore, the degree of opening does not differ between when the control voltage is increased and when it is decreased. Therefore, the opening characteristic can be improved and the hysteresis characteristic can be eliminated.

In addition, the opening degree of the proportional control valve is determined by the effective value of the energized current due to its mechanical structure, so that the electric power for energization can be reduced, and the amount of heat generated can be reduced.

[Example] Next, an example in which the proportional valve drive circuit of the present invention is used in a gas water heater will be described based on the drawings.

The gas water heater of this embodiment, which is schematically shown in FIG. 2, has a combustor 1
0, a fuel pipe 20, a water pipe 30, and a control device 40.

The combustor 10 is provided in the water heater case 1 and includes a burner group 11 in which a plurality of ribbon burners are arranged in two rows, and a combustion fan 12 that supplies combustion air. Fuel gas is supplied to the burner group 11 from the nozzle 13, and the combustion fan 1
Combustion is carried out by the combustion air supplied by 2,
Combustion gas generated by combustion is exhausted from the exhaust port 2.

Above near the burner group 11 is a sparker 14 of the ignition device.
, a flame rod 15 for flame detection is provided.

The fuel pipe 20 supplies fuel gas to the nozzle 13, and is provided with a main solenoid valve 21, a main solenoid valve 22, and a proportional valve 23 in order from the upstream side, and downstream of the ratio side valve 23, a main solenoid valve 21, a main solenoid valve 22, and a proportional valve 23 are provided. The fuel pipe 20 is branched to supply fuel gas to each station, and one of the branched fuel pipes 20
is equipped with a switching valve 24 in order to stop combustion in one of the burner groups 11 arranged in two rows.

The proportional valve 23 adjusts the supply pressure of the fuel gas supplied from the nozzle 13 to the burner group 11 in proportion to the applied current.

The water pipe 30 includes a supply pipe 31 and a hot water supply pipe 31a connected to a water supply source and a hot water supply port (not shown), respectively, and a heat exchanger 32 and a bypass pipe 3 provided to communicate these.
It consists of 2a. Heat exchanger 32 and bypass pipe 32a
A bypass valve 33 is provided at the merging section on the downstream side. A portion of the water supplied from the supply pipe 31 is transferred to the heat exchanger 3
2, the remaining portion is led to the hot water supply pipe 31a via the bypass pipe 32a, and the water heated by the heat exchanger 32 and the water directly passed through the bypass pipe 32a are:
The ratio is adjusted by the bypass valve 33.

On the other hand, a water flow control valve 34, a water flow sensor 35, and an inlet water temperature thermistor 36 are installed in the supply pipe 31 from the upstream side.
A is provided with a hot water temperature thermistor 38, respectively.

As shown in FIG. 3, the control device 40 includes a microcomputer 42 serving as the center of the control device 40 and having an interface with an input/output circuit 50, a safety circuit 43 for ensuring safety, and a solenoid valve energizing relay circuit 44. It consists of a power supply unit 45 that supplies power to all of these, and each circuit of the input/output circuit 50, and a controller 46 that operates the operation of the gas water heater, and a microcomputer 42 that controls the type of gas used and the operating mode. A mode setting circuit 47 is provided to set the mode in advance at the time of shipment from the factory or when installing the gas water heater, depending on the presence or absence of water heater, hot water supply capacity, exhaust equipment, etc.

The safety circuit 43 sends a power stop signal to the microcomputer power supply 45 to stop power supply to the microcomputer 42 when a combustion stop signal is input from the microcomputer 42, the flame detection circuit 58, and the water flow circuit 59, respectively.
Output to a.

The solenoid valve energizing relay circuit 44 is a relay circuit for energizing the original solenoid valve 21, the main solenoid valve 22, and the switching valve 24, respectively, in response to a control signal from the microcomputer 42.

When a plug (not shown) is inserted into an outlet, the power supply section 45 converts the electric power for operating each circuit of the control device 40 into the voltage necessary for each circuit and constantly supplies it.
In this embodiment, a microcomputer power supply 45a that supplies power to the microcomputer 42 and a solenoid valve energizing relay circuit 4 are used.
The relay circuit power supply 45b that supplies power to the relay circuit 45b has a switching function that stops the power supply in response to a combustion stop signal, and stops the operation of the microcomputer 42 and stops energizing each electromagnetic valve to stop the fuel supply. Stop supply.

The input/output circuit 50 is a circuit for exchanging signals with each of the above-mentioned parts provided in the gas water heater. The input/output circuit 50 includes a sparker circuit 51 that generates a high voltage to cause a spark discharge to the sparker 14 and detects the spark discharge in the sparker 14, and a sparker circuit 51 that detects the spark discharge in the sparker 14, and determines the temperature from the resistance value of each thermistor arranged in the water tube 30. a water temperature detection circuit 53 for obtaining a signal; a fan circuit 55 for driving the combustion fan 12 based on a control signal from the microcomputer 42 and outputting a pulse signal for detecting the rotation speed of the combustion fan 12; A pulse signal from the water flow sensor 35 generated in accordance with the amount of water passing through the water pipe 30 is transmitted to the microcomputer 42, and when the amount of water passing through the wood pipe 30 falls below a certain level, power supply is cut off. The switching signal for relay circuit power supply 45b of power supply section 45
and five water flow circuits transmitting to the safety circuit 43 and the proportional valve port passage 60.

The proportional valve circuit 60 is a proportional valve drive circuit of the present invention that energizes the proportional valve 23 that adjusts the fuel gas, and as shown in FIG.
The proportional valve 23
energize.

The terminal 64 is connected to the positive input terminal 61a of the operational amplifier 61.

The operational amplifier 61 has a positive input terminal 61a and a negative input terminal 61.
The base of a transistor 62 is connected to the output of the operational amplifier 61 through a resistor 65.

The transistor 62 is an NPN transistor whose emitter is grounded, and outputs a current amplified according to the output voltage of the operational amplifier 61 to drive the transistor 63. The base of a transistor 63 is connected to the collector of the transistor 2 through a resistor 66.

The transistor 63 is a high-power PNP1-transistor provided for energizing the proportional valve 23, and its emitter is connected to the proportional valve power source 45c that supplies electric power.
The output current of the transistor 62 is amplified to drive the proportional valve 23 connected to the collector.

The proportional valve 23 is grounded through a resistor 67.

The resistor 67 is provided to control the voltage difference between both ends of the drive coil of the proportional valve 23 according to the control voltage of the microcomputer 42, and the connection point 69 between the resistor 67 and the proportional valve 23 is connected to the feedback circuit. A negative input terminal 61b of the operational amplifier 61 is connected to the negative input terminal 61b of the operational amplifier 61 by a conducting wire 70 forming a negative feedback circuit, and a voltage dropped by the proportional valve 23 is input to the negative input terminal 61b.

A capacitor 68 forming a differential circuit is connected between the negative input terminal 61b and the positive input terminal 61a. The capacitor 68 differentiates the voltage drop fed back to the negative input terminal 61b and inputs the differentiated voltage to the positive input terminal 61a.

Therefore, in the proportional valve passage 60, the conductor 70 and the capacitor 6
8 forms an oscillation circuit, and when a control voltage is input to the terminal 64, the operational amplifier 61 and the transistor 62.
In this embodiment, the oscillation frequency is approximately iok++z, which oscillates at a frequency determined by each current amplification factor of 3 and the capacitance of the capacitor 68.

In the proportional valve circuit 60, the operational amplifier 61 is operated by power supplied from a constant voltage power supply (not shown) of the power supply section 45, and the transistors 62 and 63 are operated by power supplied from the proportional valve power supply section 45c.

The proportional valve power supply section 45c includes a transformer 48 having a primary coil (not shown), and a bridge diode 49 connected to the secondary coil 48a for full-wave rectification of the output voltage of the secondary coil 48a of the transformer 48. The alternating current power from the power source is appropriately converted into voltage, subjected to full-wave rectification, and then supplied directly to the emitter of the transistor 63.

The gas water heater of this embodiment having the above configuration operates as follows.

When the user turns on the operation switch using the controller 46, sets the hot water temperature, and operates a faucet (not shown), the water supplied through the supply pipe 31 passes through the water flow control valve 34 and the water flow sensor 35, and heats up. The water flows into the exchanger 32 and the bypass pipe 32a, the respective outflow amounts are adjusted by the bypass valve 33, and flows out from the hot water supply port (not shown) via the hot water supply pipe 31a.

When a predetermined number or more of pulse signals corresponding to the water flow from the water flow sensor 35 are detected, a spark discharge is performed to the sparker 14 as an ignition operation of the combustor 10.

When spark discharge at the sparker 14 is detected, the former solenoid valve 2
1 and the main solenoid valve 22 are energized, fuel gas is ejected from the nozzle 13, mixed with combustion air, supplied to the burner group 11, and ignited by the sparker 14.

When the ignition occurs within a certain period of time and is detected by the flame rod 15, the microcomputer 42 uses the detection signals from the inlet water temperature thermistor 36, the outlet water temperature thermistor 38, and the water flow sensor 35, and the setting signal of the controller 46 to determine the necessary The combustion fan 12, the proportional valve 23, the switching valve 24, the bypass valve 33, and the water flow control valve 34 are controlled based on the calculation results.

At this time, the proportional valve 23 is driven by the proportional valve port path 60 in accordance with the control voltage from the microcomputer 42 .

In the proportional valve circuit 60, the control voltage from the microcomputer 42 inputted from the terminal 64 is inputted to the positive input terminal 61a of the operational amplifier 61.

Further, a conductor 70 is connected to the negative input terminal 61b of the operational amplifier 61.
The voltage at the connection point 69 is negatively fed back, and furthermore, the voltage at the six connection points is differentiated by the capacitor 68 and made positive (i'rM), and the voltage at the connection point 69 is input to the positive input terminal 61a.
Now, the oscillation circuit is formed and oscillates.

Therefore, the output voltage corresponding to the control voltage from the microcomputer 42 is amplitude-modulated by the formed oscillation circuit as shown by the solid line A in FIG. 4, and the proportional valve 23 is energized with an amplitude-modulated current. .

In this case, if the control voltage from the microcomputer 42 differs, the amplitude will change depending on the control voltage, but the oscillation frequency will not change.

Since the proportional valve 23 cannot follow changes in the applied current, the valve body of the proportional valve 23 exhibits an opening corresponding to the effective value of the applied current while making slight vibrations, thereby causing the fuel pipe 20
The fuel gas passing through is regulated.

Thereafter, when there is a change in the hot water tap temperature or the set temperature, the control voltage of the proportional valve 23 is changed in accordance with the change, and the combustion amount is changed.

In this way, the valve body of the proportional valve 23 does not displace according to the waveform of the applied current, but exhibits an opening corresponding to the effective value of the applied current while making slight vibrations, so that the valve body does not displace according to the waveform of the applied current. Secondary pressure corresponding to the control voltage can be obtained immediately.

The control characteristics of the proportional valve 23 by the proportional valve port path 60 of this embodiment are shown by the solid line C in FIG. As is clear here, according to this embodiment, the hysteresis is greatly reduced compared to the characteristics of the conventional drive circuit shown by the solid line in FIG.

In addition, in FIG. 5, since the entire opening degree changeable range of the proportional valve 23 is shown one after the other, hysteresis appears in the portion where the opening degree is large, but excluding the range where this hysteresis occurs. If you drive the proportional valve,
Characteristics with almost no hysteresis can be obtained.

In addition, due to its mechanical structure, the opening degree of a proportional control valve is determined by the effective value of the energizing current, so it is possible to reduce the power required for energizing, and the amount of heat generated by the transistors used to drive the proportional valve can be reduced. can be reduced.

In addition, the proportional valve power supply section 45c only needs to perform full-wave rectification of the power supplied to the proportional valve 23, and there is no need to particularly provide a smoothing circuit after rectification, which simplifies the configuration.

Although this embodiment shows an example of a proportional valve used for fuel adjustment in a water heater, similar effects can be obtained with any device that uses fluid.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a proportional valve circuit of a gas water heater using the present invention, Fig. 2 is a configuration diagram showing an outline of the gas water heater of this embodiment, and Fig. 3 is a gas water heater of this embodiment. 4 is a waveform diagram showing the current flowing to the proportional valve in the control device of this embodiment, and FIG. 5 is a characteristic diagram showing the opening degree of the proportional valve with respect to the control voltage in this embodiment. , 6th
The figure is a characteristic diagram showing the opening degree of the proportional valve with respect to the control voltage in a conventional drive circuit. In the figure, 23... proportional valve (proportional control valve), 60... proportional valve circuit (proportional valve drive circuit), 61... operational amplifier (
differential amplifier circuit), 61a... positive input terminal, 61b...
・Negative input terminal, 63...Transistor (proportional valve energizing circuit), 67...Resistor (drop voltage detection means), 68...
- Capacitor (positive feedback circuit), 70... conductor (negative feedback circuit).

Claims (1)

[Scope of Claims] 1) A proportional valve drive circuit that drives a proportional control valve whose opening degree corresponds to an energized current according to a control voltage, comprising a positive input terminal and a negative input terminal into which the control voltage is input. , a differential amplifier circuit that outputs a voltage according to the voltage difference between the positive input terminal and the negative input terminal, and a proportional valve energization that energizes the proportional control valve with a current that corresponds to the output voltage of the differential amplifier circuit. a circuit, a voltage drop detection means for detecting a voltage drop due to the proportional control valve, a negative feedback circuit that negatively feeds back the voltage drop to the negative input terminal, and a differential of the voltage drop and positive feedback to the positive input terminal. What is claimed is: 1. A proportional valve drive circuit comprising: a positive feedback circuit;