JPS6047604B2 - temperature control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device, and relates to a temperature control device in which a voltage comparator and a resistor for setting the voltage of an input terminal are provided in separate units and combined to form one temperature control device. .

A conventional configuration will be explained with reference to FIG.

The following describes a case where the present invention is used in a combustion control device for controlling a burner in a water heater or the like according to the temperature of the load. 1
is a power supply, 2 is a negative characteristic thermistor that detects the temperature of the burner load, for example, hot water temperature, 3 is a voltage comparison circuit, 4, 5,
6 is a voltage setting resistor, 7 is a hysteresis resistor, and 8 is a resistor, which constitute a temperature detection circuit.

Reference numeral 9 denotes a combustion control circuit that controls the combustion of the burner based on the temperature signal input from the terminal 9a, and a timer that controls the timing of an ignition circuit, a flame detection circuit, a pre-purge, etc.
It consists of a control circuit that controls the blower, fuel valve, etc. according to the sequence.

In the above, the voltage applied to the input terminal + of the voltage comparison circuit 3 is a reference voltage determined by the resistors 4, 5, and 7, and the voltage applied to the input terminal - is determined by the resistance 6 and the resistance of the negative characteristic thermistor 2.

When the load is low temperature, the resistance of the negative characteristic thermistor 2 is large, so the voltage applied to the input terminal of the voltage comparator circuit 3 is
The output is at the L level, the combustion control circuit 9 starts the combustion operation, and the burner starts combustion. When the load temperature rises and reaches the set temperature, the resistance value of the negative characteristic thermistor becomes smaller, and the voltage applied to the input terminal of the voltage comparison circuit 3 becomes higher on the 1st side than on the 1st side, the output becomes H level, and the combustion operation is stopped. let Among the above components, the power supply 1, voltage comparison circuit 3, resistors 4 and 8, and combustion control circuit 9 are arranged on the main board.

On the other hand, the resistors 5, 6, and 7 are arranged on the sub-board 10, and are detachably attached to the main board via connectors 11a to 11d. Furthermore, since the negative characteristic thermistor 2 is located far away from the combustion control device, it is generally
, 12b are connected to the main board. The reason why the resistors 5, 6, and 7 for setting the reference voltage, that is, the resistors 5, 6, and 7 for setting the operating temperature are provided on a sub-board different from the main board is that even if the combustion control sequence and pre-purge timing are the same, the hot water If the purpose of the heat exchanger or the configuration of the heat exchanger is different, the combustion start temperature and combustion stop temperature may differ.
It is convenient to provide common parts on the main board as shown in Figure 1, and provide resistances for setting different operating temperatures for each product on the sub-board so that they can be integrated into one when configuring the combustion control device. It is meant to be.

Here, the resistor 4 is provided on the main board because the resistor 5,
Since the set value can be changed by changing the minimum number of resistors 6 and 7, resistors 4 having a common resistance value are provided on the main board. Now, if you forget to connect the sub-board 10, which has a resistance for setting the operating temperature, to the main board, the voltage comparator circuit 3
No bias is applied to each input terminal from the power supply, and each input terminal is approximately 0V.

Therefore, the state of its output is determined by the input bias current of the voltage comparison circuit 3 and the value of the resistor thermistor 2,
When the load is low temperature (the resistance value of the negative characteristic thermistor 2 is large), the output power becomes the L level and combustion starts. Combustion will stop if the load becomes too hot, but this situation is both inconvenient and extremely dangerous. The present invention has been made to improve these drawbacks.

In other words, if the resistance for setting the operating temperature is not connected,
A resistor is provided at the input terminal of the voltage comparator circuit on the main board side so that the output of the voltage comparator circuit becomes an operation stop signal.
The present invention will be explained below using an embodiment shown in FIG.

15 is a resistor that applies voltage to the input terminal + of the voltage comparator circuit 3 when the sub-board 10 is forgotten to be connected;
Located on the main board.

This resistor 15 is designed to ensure that the voltage applied to the input terminal + of the voltage comparator 3 is higher than the voltage applied to the input terminal - when the sub-board 10 is not connected and the load is at a low temperature.
Moreover, the resistance value is so high that the operating temperature does not change even if the sub-board 10 is connected normally. According to this configuration, even if the sub-board is forgotten to connect, a voltage is applied to the input terminal + through the necessary resistor 15, so the output of the voltage comparator circuit 3 is always at the H level, and combustion does not occur. .

On the other hand, if the connection is normal, the resistance value will be high and the resistance 5
Because it is connected in parallel with the It is also conceivable that the above-mentioned resistor for preventing the connection being forgotten may be provided between point a and point b, if it matches well with the operating temperature during normal operation.

Furthermore, it can also be used in a cooling device that performs cooling in addition to heating.

In this specification, a heating device or a cooling device is referred to as a heat source.
As described above, in the present invention, a voltage setting resistor is detachably provided in the voltage comparison circuit, and even if the resistor is forgotten to be connected, the heat source can be prevented from operating.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional temperature control device, and FIG. 2 is a circuit diagram of a temperature control device according to an embodiment of the present invention. 1... Negative characteristic thermistor, 3... Voltage comparison circuit, 9
... Combustion control circuit, 10... Sub board, 11, 12.
··connector.

Claims (1)

[Claims] 1. A voltage comparison circuit that compares a reference voltage with a voltage to be compared using a temperature detection element whose resistance changes depending on the temperature of the load, and a connection to the ground side of the reference voltage side input terminal of the voltage comparison circuit. The main board has a common component consisting of a voltage setting resistor and a heat source control circuit operated by the output of the voltage comparator circuit, and is connected to the input terminal of the voltage comparator circuit, and has different operating temperature settings for each product. A resistor is provided on the sub-board, and the sub-board is detachably provided on the main board, and when the sub-board is not connected, the output of the voltage comparator circuit serves as a signal to stop the operation of the heat source. So that
A temperature control device further comprising another resistor connected to the reference voltage input terminal of the voltage comparison circuit and provided in the main body. 2. In claim 1, the another resistor is
A temperature control device in which a resistor having a high resistance value is provided in parallel with a voltage setting resistor of the detachable sub-board at the reference voltage input terminal. 3 In claim 2, the resistance value of the high resistance is higher than the reference voltage input terminal to which the high resistance is connected, which is determined by the resistance value of the temperature detection element at low temperature. Temperature control device installed at a resistance value where the voltage increases.