JPS5823534B2 - temperature control circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control circuit used in gas cooking appliances, and a maximum combustion amount supply electric current device that adjusts the gas amount of a solenoid valve to the maximum rated combustion amount of a combustor.

The present invention provides a temperature control circuit that can suppress the above unnecessary current.

An embodiment of the present invention will be described below based on the drawings.

First, the internal temperature control of a gas cooking appliance will be explained using ρU, with reference to FIG.

Reference numeral 1 indicates the inside of the cooking chamber of the gas cooking appliance, and the temperature inside the chamber is detected by a temperature sensing element 2, the signal is amplified by a comparison amplifier 3, and the gas control valve 4 is driven to control the gas sent from the gas supply pipe 5. The amount of combustion in the gas burner 6 is controlled to keep the interior of the cooking chamber at a constant desired temperature.

The simple structure and operation of the gas control valve will be explained using an electromagnetic proportional control valve as an example with reference to FIG.

7 is an electromagnetic proportional control valve. 8 is an outer body which has an inlet 9 and an outlet 10 for the fluid on both sides, and further has an intermediate opening 12 with a valve seat 11 in the passage leading from the inlet 9 to the outlet 10.

The coil 14 is wound around the cylindrical bobbin 13, and the coil 14 is wound around the bobbin 1.
3 is supported by a magnetic washer 15, and a magnetic circuit is formed via an outer body 8.

A magnetic plunger 16 is housed in the middle of the bobbin 13, and has a valve 17 at one end for opening and closing the intermediate port 12 in correspondence with the valve seat 11, and a non-magnetic member 18 at the other end.

A leaf spring 19 has one end fixed to the outside of the body 8 and the other end attached to the plunger 16 and the non-magnetic body part 18.

Next, the operation of the control valve will be explained.

When no current flows through the coil 14, the leaf spring 19
always presses the valve 17 against the valve seat 11 and prevents the plunger 16 from swinging left and right and coming into contact with the bobbin 13.

Next, when a current flows through the coil 14, an electromagnetic force is generated, which acts to pull the plunger 16 upward.

When this force overcomes the force of the leaf spring 19 pressing the valve 17 against the valve seat 11, the plunger 16 is pulled up and the valve 17 leaves the valve seat 11 and comes to rest at a position where the electromagnetic force and the force of the leaf spring 19 are balanced. do.

The opening degree of the valve 17 is determined by the electric current flowing through the coil 14. proportional to the size of the flow.

This characteristic is used to control the internal temperature of gas cooking appliances.

Next, referring to FIG. 3, a specific example of the circuit configuration of the refrigerator internal temperature support will be explained.

2 is the temperature sensing element, which is determined by resistors 20, 21, and 22, and is compared with the reference value by a differential amplifier consisting of transistors 24, 25, emitter resistance 23, and collector resistance 26 of the transistors. A signal proportional to the difference in temperature signals is amplified by a valve driving transistor 27, and the current in the coil 14 of the electromagnetic proportional control valve 7 is changed.

The temperature inside the refrigerator is controlled by changing the amount of gas.

28 is an emitter resistor of the transistor 27, and 30 is a diode for absorbing surge generated from the coil 14.

FIG. 4 shows the relationship between the coil current of the valve and the controlled gas amount Q, where the coil current varies.

When , the maximum rated combustion amount Q of the combustor.

flows, and in the case shown, the coil current is in the region A of 1° or more.
In this case, the gas amount is limited by the gas passage resistance of the combustor piping, etc.
Said Q.

It shows characteristics that do not change. In addition to this column, the maximum rated combustion amount Q of the combustor is determined by the electromagnetic proportional control valve 7 itself.

In some cases, the coil current is limited to I.

When the gas amount increases from the above maximum rated combustion amount Q.

increase more. In the above characteristics, not only is it completely useless even if a current of 10 or more is passed through the coil 14, but in some cases, the maximum rated combustion amount Q of the combustor.

There is a risk of supplying more gas.

Furthermore, a large current flows through the coil 14 due to fluctuations in the power supply voltage, which is also undesirable in terms of temperature rise.

Also, in the valve, when a large current exceeding a certain value flows through the coil 14, the plunger 16 is attracted to the bobbin 13, and the coil current is interrupted.

There are some valve bodies in which the valve body does not operate proportionally even if it enters the control region B below.

In the above sense, the single maximum current flowing through the coil 14 is the current generator that supplies the maximum rated combustion amount of the combustor.

Or, it may be designed to a value 11 higher than that to prevent unnecessary coil current from flowing.

FIG. 5 shows the relationship between the resistance value R2 of the temperature sensing element 2 and the current {circle around (2)} flowing through the coil 14, in short, the circuit characteristics of FIG. 3.

The present invention provides a maximum current 1 flowing through the coil 14 as described above.
One work.

It is intended to limit the number to 11 or more.

Next, the operation of the circuit shown in FIG. 3 will be explained.

The current flowing through the coil 14 is the transistor 2 for driving the valve 1.
It is determined by the voltage generated across the emitter resistor 28 of 7 and the resistance value of 28.

Further, the voltage of the resistor 28 is the same as that of the valve driving transistor 27.
When the collector-emitter voltage of the transistor 25, which is a signal source, is saturated, it is determined by the ratio of the values of the emitter resistance 23 and the collector resistance 26 of the transistor 25.

Therefore, the maximum coil current E is the resistance 23.26.28
So I.

Or it can be kept down to ■1.

This method will be explained according to FIG.

FIG. 6 shows a circuit in which a constant voltage diode 32 is connected in parallel with the resistor 26 in the circuit of FIG.
By regulating the voltage of the resistor 28, the maximum coil current can be set to one.

It is limited to 11 or more.

FIG. 7 shows another method, in which a series resistor 33.34 is connected in parallel with the power supply 31 in the circuit of FIG. 3, and a cathode is connected to the midpoint of the two resistors 33.34. A diode 35 whose anode is connected to one end of the resistor 26 on the power source side is added.

The midpoint potential is determined by the size of the resistors 33 and 34, and when the potential of the resistor 26 exceeds the midpoint potential, the maximum base potential of the valve driving transistor 27 is regulated by bypassing the current through the diode 35. Then, calculate the maximum coil current.

Or it can be limited to more than ■1.

It is clear that even if the resistor 34 is replaced with a constant voltage diode, the coil current can be limited as described above.

FIG. 8 shows a transistor 3 in place of the diode in FIG.
6 was used.

The operation of the control circuit shown in FIGS. 6 to 8 above is such that no matter what state the temperature sensing element 2 is in, the valve driving transistor 2
This can be confirmed by the fact that 7 never saturates.

Note that the present invention is not limited to the above embodiments.

As described above, according to the present invention, a fully open electrician is provided.

The above unnecessary current can be kept to a minimum, leading to energy savings.

Further, the temperature rise of the coil itself can be kept to a minimum, which is advantageous in terms of use of the coil.

Furthermore, by limiting the emitter resistance of the valve driving transistor and the emitter resistance and collector resistance of the signal transistor serving as the signal source, it can be easily implemented without increasing the number of parts.

Further, by using a constant voltage diode, the base potential of the valve driving transistor can be determined accurately, so that the maximum current can be reliably limited.

Moreover, if two series resistors connected in parallel with the power supply and a diode or a transistor are used instead of the constant voltage diode, an inexpensive circuit configuration can be achieved.

[Brief explanation of the drawing]

Figure 4 is a diagram of the automatic temperature control system for gas cooking appliances.
Figure 3 shows the configuration of the electromagnetic proportional control valve, Figure 3 shows the specific temperature control circuit, Figure 4 shows the relationship between the coil current and control gas flow rate, and Figure 5 shows the relationship between the resistance value of the temperature sensing element and the coil current. FIG. 6 is a temperature control circuit diagram showing one embodiment of the present invention, and FIGS. 7 and 8 are temperature control circuit diagrams showing other embodiments. 2... Temperature sensing element, 4... Gas control valve, 7... Electromagnetic proportional control valve, 14... Coil, 17... Valve, 25
... Signal transistor, 23.26 ... Collector and emitter resistance, 27 ... Valve drive transistor, 28 ... Emitter resistance, 32 ... Constant voltage diode, 33° 34 ... Series resistance , 35...diode, 36... transistor.

Claims (1)

[Scope of Claims] 1. In a temperature control circuit using a temperature sensing element that detects the temperature of a heated limb part and an electromagnetic valve that controls the amount of combustion based on a signal from the element, the maximum current flowing through the coil of the valve is 1. A temperature control circuit comprising: a circuit that limits current to a certain value greater than a coil current value that supplies the maximum rated combustion amount of a combustor, and prevents a coil current exceeding the certain value from flowing. 2 A transistor for driving a solenoid valve and another signal transistor as a signal source for the valve driving transistor, and an output side emitter resistance and a collector resistance of the signal transistor, and an output side emitter resistance and a collector resistance of the valve driving transistor. 2. The temperature control circuit according to claim 1, wherein a maximum coil current of said valve is limited by an emitter resistor. 3. It has a transistor that drives a solenoid valve, and a constant voltage diode provided in the signal source of the valve driving transistor, and the diode suppresses input or output fluctuations to a certain value to limit the maximum coil current of the valve. A temperature control circuit according to claim 1, characterized in that the temperature control circuit is configured as follows. 4 A transistor that drives a solenoid valve, two series resistors connected in parallel with the power supply provided in the signal source of the valve drive transistor, and a diode or pace connected to a cand at the midpoint of the two resistors. claim 1, wherein the clipper circuit is configured to suppress input or output fluctuations to a certain value to limit the maximum coil current of the valve. Temperature control circuit as described.