JPS5827294Y2 - Differential temperature thermostat - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a temperature control thermostat that operates by detecting a temperature difference.

Generally, in central heating, the indoor temperature is compared with the outside air temperature, etc., and the indoor temperature is set to be higher than the outside air temperature by a predetermined amount, or the temperature difference between the outside air temperature and the outside air temperature is changed in proportion to the outside air temperature. However, this control is done by switching the strength of the indoor fan coil unit, and the circulation pump that circulates hot water to each room is operated continuously regardless of this temperature control. When the fan coil unit runs slowly or stops,
Since more heat than necessary is constantly circulating in the pipes, there is a disadvantage that fuel and electricity are wasted.

The present invention was made in view of the above drawbacks, and the control target,
For example, temperature-sensing elements with the same characteristics placed at the inlet and outlet of the boiler are connected to adjacent sides of the signal circuit bridge, and the temperature difference between the boiler outlet and inlet is sensed to operate the circulation pump. It also provides a differential temperature thermostat that controls shutdown and provides ideal central heating that saves electricity.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

As shown in FIG. 1, the temperature control thermostat 1 of the present invention is comprised of a power supply circuit 2, a signal circuit 3, a control circuit 4, and an output circuit 5.

The power supply circuit 2 is constructed by combining a power transformer 6, a diode 7, and a smoothing capacitor 8 connected to an AC power source.

The signal circuit 3 also includes two thermistors 9, 10, a correction resistor 11. A resistor 12 and a semi-fixed resistor 13 are connected to form a bridge.

The control circuit 4 includes an integrated circuit 14 for temperature control, differential resistors 15 and 16 for the outside lights, and a noise prevention capacitor 17.

Although not shown, the integrated circuit 14 includes a differential amplifier and a Schmitt circuit therein.

The signal output of the previous stage signal circuit 3 is then transmitted to the integrated circuit 14.
The differential amplifier in is connected to the bases of two built-in transistors, respectively.

The output circuit 5 includes a relay coil 18, a reverse starting force absorbing diode 20, and a relay contact 19.

One end of this relay contact 19 is connected to the circulation pump 22 of the outlet pipe of the boiler 21, and the other end is connected to an AC power source, and the circulation pump 22 is controlled by opening and closing the contact 19 by turning on and off the coil 18.

Now, the two thermistors 10 and 9 described above have the same negative characteristic, and are disposed in the inlet pipe 23 and outlet pipe 24 of the boiler 21, respectively, as shown in FIG.

Next, the operation of this embodiment will be explained.

If the thermistors 9 and 10 are now at the same ambient temperature, there is no signal output and the final stage transistor of the integrated circuit 14 is non-conducting, so the relay coil 1
8 is in the off state and the relay contact 19 is open, so the pump 22 is stopped.

Then, when the ambient temperature of the thermistor 9 rises from this state, that is, the resistance value decreases, a signal output appears in the signal circuit 3 due to the imbalance of the bridge, and the final stage transistor of the integrated circuit 14 becomes conductive. Coil 18 is turned on, contact 19 is closed, and pump 22 is operated.

The thermistor correction resistor 11 is used to finely adjust the variations in the two thermistors 9.degree. 10 to have the same characteristics.

Here, the signal circuit 3 is set to the third position by adjusting the semi-fixed resistor 13.
Assume that the setting is made at point P1 in the figure.

Of course, in this case, when the thermistor 10 increases due to a change in temperature t, the resistance value decreases, and the relay coil 1
8 is in an off state, and when the temperature decreases, the resistance value increases and the relay coil 18 is in an on state.

Then, when the temperature inside the outlet pipe 24 is T1, that is, the temperature of the thermistor 9 is T1, the pump 22 is activated by the other thermistor 10.
is controlled by changes in the temperature t.

That is, the pump 22 is controlled to stop at the temperature t1Jt and operate at the temperature t1-Jt' at the temperature T1.

However, it is assumed that the temperature changes At and It' are Jt'>Jt, and there is a relationship T>t between the temperatures T and t.

Moreover, at point P2, since thermistors with the same characteristics are used, the resistance values of thermistors 9 and 10 increase at the same rate as the temperature changes from T1 to T2, so the changes in temperature J t and J t' There is no change in the pump 22, the pump 22 is turned off at the temperature T2Jt, and the pump 22 is turned off at the temperature T2It'.
is controlled so that it is turned on.

This relationship is also the same at point P3.

In this way, the pump 22 as a controlled object maintains a constant ratio between one temperature T and the other temperature t, regardless of the temperature of the hot water in the detection part, that is, the inlet pipe 23 and the outlet pipe 24, and detects the temperature difference. Therefore, if the user determines the set temperature of boiler 21, boiler 2
When the temperature difference between the hot water temperature in the inlet pipe 23 and the outlet pipe 24 becomes smaller, the pump 22 will stop, thereby making it possible to save electricity. Since the temperature can reach the target value quickly, fuel can be saved.

According to the present invention, the circulation pump can be operated only when the temperature difference between the inlet and outlet of the boiler exceeds a certain level, that is, when the room temperature drops and heating operation is required.
Energy saving can be achieved by preventing excessive heat from circulating in the pipes when heating operation is stopped.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram showing an embodiment of the differential temperature thermostat of the present invention, FIG. 2 is a system diagram when used in the same boiler, and FIG. 3 is a characteristic diagram of the present invention. 1... Differential temperature thermostat, 3... Signal circuit, 5... Output circuit, 9, 10...
- Thermistor as a temperature sensing element, 21... Boiler, 22... Circulation pump.

Claims (1)

[Scope of utility model registration request] In a system in which a heat medium is heated in a boiler and this heat medium is circulated by a circulation pump, temperature sensing elements having the same characteristics arranged at the inlet and outlet of the boiler are respectively connected to adjacent sides of the bridge. A differential temperature thermostat comprising: a signal circuit that outputs a signal when the bridge becomes unbalanced due to a temperature difference between the inlet and outlet of the boiler; and an output circuit that operates the circulation pump by the output of the signal circuit. .