JP3191368B2 - Safety devices for heating appliances - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a heating appliance such as a water heater, a cooking appliance, a heater, etc., which safely stops operation when an abnormality is detected in the appliance.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a safety device of this type includes a safety device 3 (for example,
If the device is in an abnormal state (for example, abnormally high temperature), the wiring between the power supply 1 and the control circuit 2 is cut off (for example, the thermal fuse 3a or the bimetal switch 3b). The operation of the device has been stopped by fusing the 3a or turning off the contact of the bimetal switch 3b).

[0003]

However, in the conventional configuration, when the safety device 3 is actuated and the service person happens to not prepare a replacement part, the both ends of the connector 5 are short-circuited as indicated by broken lines. As a result, the power supply 1 and the control circuit 2 are often connected so that the device can be operated immediately. Then, if the device becomes abnormal again in this state, the safety device 3 does not work, so the device continues to operate in the abnormal state, resulting in a burn or a fire or a very dangerous condition. Was.

Accordingly, a first object of the present invention is to invalidate an emergency operation even if the connection terminals of wiring provided with a safety device are simply short-circuited.

Further, in addition to the above-mentioned short-circuit treatment, even if the current detector of the safety device is short-circuited, the emergency operation is invalidated.
The purpose of.

[0006]

In order to achieve the above-mentioned first object, a first means of a safety device for a heating device according to the present invention comprises a control device for controlling the operation of the device and a drive current for the control device. A control circuit that outputs power to the control circuit, a power supply that supplies power to the control circuit, an intermediate wiring and a terminal wiring connected between the control circuit and the power supply via a connection terminal on the way, and an intermediate circuit that detects abnormal use of the control means. A safety device for interrupting the current of the wiring, and an energization detector provided on the intermediate wiring to detect the presence or absence of energization, and a non-energization detection signal of the energization detector even if the safety device short-circuits the connection terminal after the energization is interrupted. Thus, the control circuit stops outputting the drive current.

In order to achieve the above-mentioned second object, a second means of the present invention provides a current detector as an energization detector for outputting an energization detection signal in a predetermined range to a control circuit via a specific resistance. And a signal line to be transmitted, and a connection terminal for a control circuit of the signal line, and the connection terminal and the connection terminal between the intermediate wiring and the terminal wiring are short-circuited by a short-circuit line having a small resistance value after energization of the safety device is cut off. Also, the control circuit receives a signal different from the detection signal of the current detector and stops outputting the drive current.

[0008]

According to the above-mentioned first means, the heating device safety device of the present invention provides a heating device safety device which detects an abnormality in the control means and shuts off the power supply to the control circuit when the safety device detects an abnormality in the control means. Even if the connection terminals provided on the intermediate circuit are short-circuited and an attempt is made to recover the interruption of the energization of the intermediate wiring by the safety device, the energization detector detects the non-energization of the intermediate wiring. The control circuit that has received the detection signal stops the drive current of the control means, and can prevent unsafe emergency operation in which the safety device does not operate normally.

According to the second means, even if the connection terminal of the signal line is short-circuited by a short-circuit line having a smaller resistance value in addition to the above-mentioned short-circuit treatment, the current detector detects an energization exceeding a predetermined range. However, the control circuit stops the drive current output, thereby preventing the emergency operation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a safety device for a heating device according to the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 shows a gas water heater according to one embodiment of the present invention, in which water supplied to a heat exchanger 10 is heated by a burner 11 to increase the temperature. Burner 11 feeds fuel gas to proportional valve 12
, And supply it to the burner 11. The control means 13 including the heat exchanger 10, the burner 11, and the proportional valve 12
The heat exchanger 10 is overheated to a high temperature due to the incomplete combustion or the like, and the heat exchanger 10 is deteriorated and damaged by high-temperature oxidation.

A thermal fuse 14 as a safety device is connected to the intermediate wiring 16 at a connection point 15, detects an abnormal use of the heat exchanger 10, blows it at a predetermined temperature, and cuts off the current supply to the intermediate wiring 16. A current detector 19 having a diode 17 and a transistor 18 is similarly connected to the intermediate wiring 16. A signal line 20 is connected to the transistor 17, and the other end of the signal line 20 is screwed into connection terminals 22 and 23 provided on a terminal board 21.
4 is screwed into the screw hole 25 for connection. Connection terminal 22,
23 is fixedly connected to a signal line 26, and the other end of the signal line 26 is connected to a control circuit 28. Both ends of the intermediate wiring 16 are connected to connection terminals 29 and 30, and terminal wirings 31 and 32 are connected to the connection terminals 29 and 30. The other ends of the terminal wires 31 and 32 are connected to a power supply 34 and a control circuit 28. The control circuit 28 is connected by another wiring 35 for supplying power from a power supply 34 and outputs a drive current for the proportional valve 12.

Next, the operation when the thermal fuse 14 detects an abnormality due to overheating of the control means 13 based on the above configuration will be described.

When the temperature fuse 14 is detected as abnormal and blows, the intermediate wiring 16 is cut off the current, one of the power supply lines 36 composed of the terminal wiring 31, the intermediate wiring 16 and the terminal wiring 32 becomes unconductive, and the control circuit 28 The power supply of the power supply 34 is cut off. The control circuit 28 controls the proportional valve 1
2 cannot output the drive current, the combustion of the burner 11 stops, and the abnormal operation is stopped. If it becomes impossible to supply hot water due to the stoppage of operation, a failure repair operation is performed.

Then, as in the prior art, the connection terminals 29, 3
The intermediate wiring 16 is removed by loosening the screw 24 of No. 0, and the connection terminals 29, 30 are connected by short-circuit wires 37 such as lead wires as shown by broken lines.
Is short-circuited, and an emergency treatment is performed so that the power supply 34 and the control circuit 28 can be energized. With this measure, the power is instantaneously supplied from the power supply 34 to the control circuit 28. However, since the intermediate wiring 15 is not energized, the current detector 19 does not input an energization detection signal to the control circuit 28. Therefore, the control circuit 28 does not output a drive signal to the proportional valve 12 and does not restart the operation.

The installation of the current detector 19 also serves to prohibit emergency treatment. The current detector 19 rectifies the current of the intermediate wiring 16 by the diode 17, and turns on the transistor 18 when the rectified DC current becomes a predetermined value or more. Signal line 20,
26 is applied with a voltage from the control circuit 28, and the transistor 1
8 turns on, the signal lines 20 and 26 are connected to the transistor 18
The current flows through. This current becomes a small current having a predetermined width due to the large resistance of the transistor 18, and the control circuit 28 outputs a drive current to the control means 13 when receiving the current of the predetermined width. And the connection terminal 2
Since the short-circuiting of the terminals 9 and 30 is invalid, the connection terminals 22 and
As shown by the broken line, it can be sufficiently predicted that a short-circuiting operation is immediately performed with a short-circuiting line 38 such as a lead wire having a small resistance value between the two.

However, at this time, power is also supplied to the control circuit 28 temporarily from the power supply line 36. However, the resistance of the short-circuit line 38 is extremely smaller than the resistance of the transistor 18, so that the signal lines 20, 26 A large current flows through.
Then, the control circuit 28 determines that the current does not coincide with the small current having the predetermined width, stops the output of the drive current, invalidates the countermeasure, and can prevent the reoccurrence of the abnormality due to the dangerous emergency operation.

The safety device is not limited to the thermal fuse 14, but a bimetal may be used as a temperature detector, and the same effect can be obtained when the abnormality is detected by using the power supply current, the pressure of gas or liquid, the humidity, and the like. . Even if the current detector 19 is simply energized by a relay or the like, the short circuit between the connection terminals 29 and 30 can be invalidated.

[0019]

As is apparent from the above description, in the first aspect of the safety device for a heating device according to the present invention, the safety device detects abnormal use of the device and supplies power from the power supply to the control circuit. Even if the connection terminals of the wiring of the safety device are short-circuited immediately after the interruption, the energization detector detects the non-energization of the wiring and stops the drive current output of the control circuit. Driving can be prevented.

According to a second aspect of the present invention, in addition to the short-circuit treatment of the connection terminal, the connection terminal of the wiring of the current detector as the conduction detector is further short-circuited by a short-circuit line having a small resistance value.
The control circuit that has received a signal different from the energization detection signal of the current detector stops the drive current output, thereby preventing a dangerous operation in which the safety device cannot operate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a heating device safety device according to the present invention.

FIG. 2 is a configuration diagram showing a conventional heating device safety device.

[Explanation of symbols]

 14 Thermal fuse 19 Current detector 22, 23, 29, 30 Connection terminal 28 Control circuit 37, 38 Short circuit wire

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H02H 3/00-3/07 H02H 7/00

Claims (2)

(57) [Claims] 1. A control means for controlling the operation of a device, a control circuit for controlling and outputting a drive current of the control means, a power supply for supplying power to the control circuit, and a connection terminal between the control circuit and the power supply via a connection terminal. The intermediate wiring and the terminal wiring connected to each other, a safety device that detects abnormal use of the control means and shuts off the current of the intermediate wiring, and an energization detector that is provided in the intermediate wiring and detects the presence or absence of energization. A safety device for a heating appliance wherein a control circuit stops outputting a drive current in response to a non-energization detection signal of the energization detector even if the connection terminal is short-circuited after energization is cut off. A current detector for outputting an energization detection signal in a predetermined range to the control circuit through a specific resistance, a signal line for transmission, and a connection terminal for the signal line control circuit; Even if the connection terminal and the connection terminal between the intermediate wiring and the terminal wiring are short-circuited by a short-circuit line having a small resistance value after the energization of the safety device is cut off, the control circuit receives a signal different from the detection signal of the current detector and drives the drive current. The safety device for a heating appliance according to claim 1, wherein the output of the heating device is stopped.