JPH026409B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention <Field of Industrial Application> The present invention mainly relates to a combustion safety device for a forced air gas instantaneous hot water heater.

<Conventional technology> Conventionally, gas instantaneous water heaters detect the set temperature, water supply temperature, hot water supply temperature, and water supply temperature, calculate the amount of combustion to obtain the optimal hot water supply characteristics, and control the amount of gas to be combusted. ing. Figure 2 is a block diagram of a conventional combustion control device, where 1 is a temperature sensing element that detects the temperature of water supply, 2 is a temperature sensing element that detects the temperature of hot water, 3 is a flow rate sensor that detects the amount of water supply, and 4 is combustion control. In the circuit, a combustion control circuit 4 receives signals from the temperature sensors 1 and 2 and the flow rate sensor 3, calculates the amount of combustion,
It is output to the proportional valve drive circuit 7 that drives the proportional valve 8. Reference numeral 9 denotes a proportional valve current detection circuit 9 that detects the current of the proportional valve 8 and converts it back into a combustion amount signal. Feedback will be provided to
Here, the proportional valve drive circuit 7 also has the role of comparing the signals obtained by the combustion control circuit 4 and the proportional valve current detection circuit 9, and performing feedback control so that the deviation is eliminated.

<Problems to be Solved> However, if the proportional valve 8 or its drive circuit 7 breaks down or the gas amount fluctuates due to an abnormality in the gas piping (not shown), feedback control will not be performed normally and the amount of gas required for combustion will change. This can lead to misfires, incomplete combustion, etc., which can lead to serious accidents.

(2) Structure of the invention <Means for solving the problem> A temperature sensing element that detects the temperature of water supply and the temperature of hot water;
In a device that calculates the amount of combustion based on a signal from a flow rate sensor that detects the amount of water supplied, and provides the calculated output to a gas proportional valve to control the amount of gas according to the amount of combustion, the proportional valve detects the proportional valve current. A valve current detection circuit, means for comparing the current signal obtained by the proportional valve current detection circuit and a set current signal calculated according to the combustion amount, and is activated when the compared deviation exceeds a certain value. It is characterized by a timer.

<Function> During combustion, the comparison means compares the current signal from the proportional valve current detection circuit and the set current signal calculated according to the combustion amount. When combustion is occurring normally, the deviation between the current signal from the detection circuit and the set current signal is small, but as described above, when a failure or abnormality occurs, the deviation becomes large. The comparison means gives an output signal to the timer when the deviation exceeds a certain value, and when the timer times up, the timer outputs an alarm signal and stops the combustion of the equipment.

<Example> Fig. 1 shows an embodiment of the present invention, and the basic combustion circuit is the same as the conventional example shown in Fig. 2 described above, so components with the same functions are given the same reference numerals. The explanation will be omitted.

The proportional valve current detection circuit 9 outputs the aforementioned inversely converted proportional valve current signal to the comparison circuit 6 in addition to outputting it to the proportional valve drive circuit 7 for feedback control.

Further, the combustion control circuit 4 outputs a set current signal obtained by calculating the combustion amount based on the signals received from the temperature sensing elements 1 and 2 and the flow rate sensor 3 to the proportional valve drive circuit 7 as well as to the comparison circuit 6.

The comparison circuit 6 compares the proportional valve current signal and the set current signal, and if the deviation exceeds a certain predetermined value, it is determined that there is an abnormality and provides an output signal to the timer circuit 5.

The timer circuit 5 operates the timer when a signal is input from the comparator circuit, and resets the timer when no signal is input.

Therefore, when the timer circuit 5 receives an output signal from the comparator circuit 6, it operates the timer, and if the comparator circuit continues to give an output signal to the timer due to a large deviation until the timer times up, the timer will not operate due to the time up. Then, an alarm signal is output to the combustion control circuit 4 to stop the combustion of the equipment. Also, even if the timer circuit receives an output signal from the comparator circuit and operates the timer, if the deviation compared by the comparator circuit becomes small before the timer times up, the output signal from the comparator circuit will stop. Reset and wait.

(3) Effects As described above, according to the present invention, even if the proportional valve or its drive circuit breaks down or an abnormality occurs in the gas piping line and the gas amount fluctuates, combustion can be stopped and accidents can be prevented. It can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a block diagram of a conventional combustion device, in which 1 and 2 are temperature sensing elements, 3 is a flow rate sensor, 4 is a combustion control circuit, 5 is a timer circuit, 6 is a comparison circuit, 7 is a proportional valve drive circuit, 8 is a proportional valve, and 9 is a proportional valve current detection circuit.

Claims (1)

[Claims] 1. The combustion amount is calculated based on the signals from the temperature sensing element that detects the water supply temperature and the water supply temperature, and the flow rate sensor that detects the amount of water supply, and the calculation output is given to the gas proportional valve to start the combustion. In a device that controls a gas amount according to a combustion amount, the proportional valve current detection circuit detects the proportional valve current, a current signal obtained by the proportional valve current detection circuit, and a set current signal calculated according to the combustion amount. and a timer that is activated by the comparison means when the compared deviation exceeds a certain value, and combustion is stopped when the timer times up. .