GB1570771A - Water heater with automatic gas ignition control - Google Patents

Description

(54) WATER HEATER WITH AUTOMATIC GAS IGNITION CONTROL (71) I, TU WU-HENG, of 33, sec. 3, Ming-Teng Road, Jui-Fang Chen, Taipei Hsien, Taiwan, a citizen of Taiwan, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a water heater with automatic gas ignition.

In the conventional water heater using gas as fuel the user is required first manually to ignite an auxiliary (pilot) burner.

The main gas valve is then opened and only then can hot water be obtained. This is a very inconvenient procedure.

Additionally, the conventional method of igniting the pilot burner can be very dangerous. Also, gas leakage may take place from time to time through the carelessness of the user. More importantly, it may cause a gas explosion if the main gas valve is opened before ignition of the pilot burner takes place.

In another respect, many components are used in the construction of conventional automatic gas water heaters, thereby making the assembly complex and the manufacture cost, therefore, high.

According to the invention there is provided a gas water heater with automatic gas ignition control comprising: A. a water level sensor, micro switch, and gas flow controller for regulating the gas flow in accordance with changes in water level above a predetermined water level, said micro switch changing states when the water falls below said predetermined level; B. an alarm mechanism including gas pressure-responsive means, said mechanism indicating when the gas pressure upstream of said controller is below a predetermined level; C. automatic gas control apparatus for controlling a pilot burner and a main burner connected to said gas flow controller; D. a high voltage electric ignition circuit for igniting said pilot burner; E. an electric ignition circuit for igniting said main burner: and wherein said automatic gas control apparatus for producing a pilot burner flame and a main burner flame, comprises: a. a gas inlet port and a gas outlet port for gas flow; b. an electromagnetic coil to produce magnetic force; c. an armature with a rubber diaphragm fixed thereon to be moved by the attraction of magnetic force produced by said electromagnetic coil, said diaphragm selectively allowing communication between said inlet port and said outlet port; and d. a spring to restore said armature back to its initial position blocking said communication when said magnetic coil ceases to function; to thereby automatically control the gas flow in accordance with an electric current in said coil.

The invention will be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a block diagram of a water heater with automatic gas ignition embodying the present invention: Figure 2 is a vertical sectional view of water pressure sensor, micro switch, and gas flow controller in the water heater of Figure 1; Figure 3A and 3B are vertical sectional views of an alarm in the water heater of Figure 1; Figures 4A and 4B are vertical sectional views of means for automatic gas control of a pilot burner and a main burner in the water heater of Figure 1; Figure 5 illustrates the gas ignition cir cuit for the pilot burner in the water heater of Figure 1; Figure 6 illustrates the high voltage ignition circuit for the pilot burner; in the water heater of Figure 1; Figure 7 illustrates the gas ignition circuit for the main burner: and Figure 8 is an electrical circuit diagram of the water heater of Figure 1.

Referring to Figure 1, a water level or pressure sensor 1 controls a micro-switch 2 to cause it to close or open according to the water level or pressure. Also, the water level or pressure sensor 1 can directly control the gas flow rate in the gas flow controller 3.

An alarm 5 operates when the gas pressure from a gas source and main valve 4 falls below a certain value.

The automatic gas ignition means for a pilot burner 6 together with a high voltage electric ignition circuit 7 starts to function when the micro-switch 2 closes (that is to say, completes an electrical circuit). Also, the gas from pilot burner nozzle 8 is ignited. The automatic gas ignition means for the main burner, together with its electric ignition circuit 9 starts to operate when the micro switch 2 is closed and the pilot burner has ignited.

The gas from the main burner nozzle 10 will be then be ignited by the operation of the gas ignition circuit 9 through gas flow controller 3.

A timer circuit 11 opens the circuits 6 and 9 if the gas is not ignited after a predetermined time.

The water heater of Figure 1 will complete the automatic gas ignition function successfully and safely with the user only opening the main gas valve, so long as there is sufficient water level or pressure.

Fig. 2 shows the preferred construction of water level or pressure sensor 1, microswitch 2 and gas flow controller 3. A water level detector 110 comprises a plate 111 to sense the water level change. A vertical rod 112 moves upward or downward due to the change in water level.

A switch button 120 of a micro switch 12 is cammed into a closed position by sloping sides of a recess 113.

The gas flow controller 3 comprises a gas inlet port 130, a gas outlet port 131, a diaphragm 133 fixed on the rod 112, and a tension spring 132. The extent of the upward movement of the rod 112 influenced by the water level will control the gas flow rate. It can be seen that the rod 112 will be pushed to its initial position by the tension force of the spring 132 when the water level falls and pushed upwardly against spring 132 when the water level rises. Thus, no gas flows if the water level falls below a safe limit; The construction of the alarm is shown in Fig. 3. If the gas pressure from the gas source is too low (Fig. 3A) a contact plate 142 of an alarm device 14 will come into contact with a limit switch 141 to complete an electric circuit to a buzzer alarm.Under normal condition, referring to Fig. 3B, the force due to the gas pressure is greater than the force of a spring 144, and gas will flow from the inlet port 140 to the outlet port 143 giving a normal gas supply.

The construction of the automatic gas control means 15 both for the pilot burner and the main burner is shown in Fig. 4.

This automatic control means 15 comprises a gas inlet port 150, gas outlet port 151, electromagnetic coil 152, armature 153, rubber diaphragm 154 and spring 155. When the micro switch 12 in Fig. 2 is closed the electromagnetic coil 152 will then be excited to produce a magnetic flux attracting the armature 153 to move it downwardly. Gas can then flow from the inlet port 150 to the outlet port 151, providing a normal gas supply (see Fig. 4B0.

The high voltage electric ignition circuits for the pilot burner are shown in Figs. 5 and 6. When micro switch 12 in Fig. 2 is closed, the ignition circuit in Fig. 5 is energised. It firstly controls an automatic gas control means to supply gas for the pilot burner by the method stated before in connection with Figure 4.

Contact points A and B of a relay RL1 are normally closed i.e. when relay RL1 is de-energised. Initially, when micro switch 12 is open, the photoresistor CDS 1 has a high resistance because it is not illuminated. When micro switch 12 is closed, transistor TR 1 is therefore nonconducting R 2 having been adjusted for ensuring that TR 1 is non conducting i.e.

"off", with switch 12 closed and no light impinging on CDS 1. In this condition transistor TR 2 is forward biased between its base P1 and its emitter which is tied to B+. Then the relay RL1 becomes energized and closes contact points B and C.

Referring to Fig. 6 due to the function of a high voltage circuit HV, the ignitor IGR will thus ignite the pilot burner.

After ignition of the pilot burner, the resistance of CDS 1 will decrease because of the illumination thereof by the pilot burner. Then transistor TR1 starts to forward conduct causing transistor TR2 to become reverse biased between its base and emitter. Since no more current flows in the relay RL 1, it will de-energize and recover to its normal state with contacts A, B closed. The high voltage ignition circuit will then cease to function, due to contact points B and C being open.

The gas ignition circuit for the main burner is shown in Fig. 7. When the micro switch 12 in Fig. 2 is closed and before the pilot burner has been ignited no current flows in the relay RL 2 with contact points D and E normally closed. In this state R 4 is adjusted so that transistor TR3 is conducting, but the resistance of CDS 2 is high enough to maintain TR 4 in the nonconducting i.e. "off" condition.

Once the pilot burner is ignited, CDS 2 is illuminated and the resistance of photoresistor CDS 2 will decrease to make transistor TR 4 become forward biased between its base and emitter. Then current flows through relay RL 2, causing contact points E and F to be closed. This will, in turn actuate an automatic gas control apparatus for the main burner to provide a normal main burner gas supply by the method of producing magnetic flux to attract the armature therein as described in connection with Fig. 4. When the main burner gas is jetted from its gas nozzle it will be ignited by the pilot burner immediately.

If the water pressure decreases below a predetermined level, the rod 112 in Fig. 2 will move downward and the micro switch 12 will open. Once the micro switch 12 is open, both ignition circuits for the pilot and main burners will be in the nonoperative state. Further, the automatic gas control, apparatus for the pilot burner and the main burner will cease to supply gas as described.

Referring to Fig. 8, AC is supplied via micro switch 12 to a transformer T1, the output of which is rectified by a rectifier D1. The timer circuit 11 is provided to act as a timing controller to the gas ignition circuits for the pilot and main burners.

The timer circuit 11 is constructed with capacitors C1, C2, C3 and resistors R8, R9 for predetermining an RC time constant, to control the bias between the base and emitter of the transistor TR5. Contact points G and H of a relay RL3 are normally closed, i.e. when relay RL3 is deenergized. The gas ignition circuit for the pilot burner is supplied with DC to start an ignition operation. If the pilot burner is not ignited after a predetermined time, transistor TR5 will conduct so that relay RL3 becomes energized and closes contact points H and J. Therefore the gas ignition circuits will cease to operate and the alarm 5 is energized.

The water heater described above is very safe and convenient because: firstly, if the system is not supplied with an adequate amount of gas, the alarm will give an early warning; secondly if any electric components in the ignition circuits are damaged or become inoperative, the circuits will cease to function and gas will flow in neither the main burner nor the pilot burner; and thirdly with only the opening of the main burner gas nozzle and igniting of the pilot burner will a proper main burner flame be automatically obtained.

WHAT I CLAIM IS: 1. A gas water heater with automatic gas ignition control comprising: A. a water level sensor, micro switch, and gas flow controller for regulating the gas now in accordance with changes in water level above a predetermined water level, said micro switch changing states when the water falls below said predetermined level; B. an alarm mechanism including gas pressure-responsive means, said mechanism indicating when the gas pressure upstream of said controller is below a predetermined level; C. automatic gas control apparatus for controlling a pilot burner and a main burner connected to said gas flow controller; D. a high voltage electric ignition circuit for igniting said pilot burner E. an electric ignition circuit for igniting said main burner and wherein said automatic gas control apparatus for producing a pilot burner flame and a main burner flame comprises: a. a gas inlet port and a gas outlet port for gas flow; b. an electromagnetic coil to produce magnetic force; c. an armature with a rubber diaphragm fixed thereon to be moved by the attraction of magnetic force produced by said electromagnetic coil, said diaphragm selectively allowing communication between said inlet port and said outlet port; and d. a spring to restore said armature back to its initial position blocking said communication when said magnetic coil ceases to function; to thereby automatically control the gas flow in accordance with an electric current in said coil.

2. A water heater according to Claim 1, wherein said armature with said rubber diaphragm fixed thereon is operable to control gas supply and gas cut-off by the electromagnetic energization or deenergization of said coil.

3. A water heater according to Claim 1, wherein said high voltage electric ignition circuits for igniting the pilot burner comprises: a switch, a first transistor and a relay in circuit with a source of electric power; a second transistor in circuit with the base of said first transistor; and a photoresistor in circuit with the base of said second transistor.

4. A water heater according to Claim

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. switch 12 in Fig. 2 is closed and before the pilot burner has been ignited no current flows in the relay RL 2 with contact points D and E normally closed. In this state R 4 is adjusted so that transistor TR3 is conducting, but the resistance of CDS 2 is high enough to maintain TR 4 in the nonconducting i.e. "off" condition. Once the pilot burner is ignited, CDS 2 is illuminated and the resistance of photoresistor CDS 2 will decrease to make transistor TR 4 become forward biased between its base and emitter. Then current flows through relay RL 2, causing contact points E and F to be closed. This will, in turn actuate an automatic gas control apparatus for the main burner to provide a normal main burner gas supply by the method of producing magnetic flux to attract the armature therein as described in connection with Fig. 4. When the main burner gas is jetted from its gas nozzle it will be ignited by the pilot burner immediately. If the water pressure decreases below a predetermined level, the rod 112 in Fig. 2 will move downward and the micro switch 12 will open. Once the micro switch 12 is open, both ignition circuits for the pilot and main burners will be in the nonoperative state. Further, the automatic gas control, apparatus for the pilot burner and the main burner will cease to supply gas as described. Referring to Fig. 8, AC is supplied via micro switch 12 to a transformer T1, the output of which is rectified by a rectifier D1. The timer circuit 11 is provided to act as a timing controller to the gas ignition circuits for the pilot and main burners. The timer circuit 11 is constructed with capacitors C1, C2, C3 and resistors R8, R9 for predetermining an RC time constant, to control the bias between the base and emitter of the transistor TR5. Contact points G and H of a relay RL3 are normally closed, i.e. when relay RL3 is deenergized. The gas ignition circuit for the pilot burner is supplied with DC to start an ignition operation. If the pilot burner is not ignited after a predetermined time, transistor TR5 will conduct so that relay RL3 becomes energized and closes contact points H and J. Therefore the gas ignition circuits will cease to operate and the alarm 5 is energized. The water heater described above is very safe and convenient because: firstly, if the system is not supplied with an adequate amount of gas, the alarm will give an early warning; secondly if any electric components in the ignition circuits are damaged or become inoperative, the circuits will cease to function and gas will flow in neither the main burner nor the pilot burner; and thirdly with only the opening of the main burner gas nozzle and igniting of the pilot burner will a proper main burner flame be automatically obtained. WHAT I CLAIM IS:

1. A gas water heater with automatic gas ignition control comprising: A. a water level sensor, micro switch, and gas flow controller for regulating the gas now in accordance with changes in water level above a predetermined water level, said micro switch changing states when the water falls below said predetermined level; B. an alarm mechanism including gas pressure-responsive means, said mechanism indicating when the gas pressure upstream of said controller is below a predetermined level; C. automatic gas control apparatus for controlling a pilot burner and a main burner connected to said gas flow controller; D. a high voltage electric ignition circuit for igniting said pilot burner E. an electric ignition circuit for igniting said main burner and wherein said automatic gas control apparatus for producing a pilot burner flame and a main burner flame comprises: a. a gas inlet port and a gas outlet port for gas flow; b. an electromagnetic coil to produce magnetic force; c. an armature with a rubber diaphragm fixed thereon to be moved by the attraction of magnetic force produced by said electromagnetic coil, said diaphragm selectively allowing communication between said inlet port and said outlet port; and d. a spring to restore said armature back to its initial position blocking said communication when said magnetic coil ceases to function; to thereby automatically control the gas flow in accordance with an electric current in said coil.

2. A water heater according to Claim 1, wherein said armature with said rubber diaphragm fixed thereon is operable to control gas supply and gas cut-off by the electromagnetic energization or deenergization of said coil.

3. A water heater according to Claim 1, wherein said high voltage electric ignition circuits for igniting the pilot burner comprises: a switch, a first transistor and a relay in circuit with a source of electric power; a second transistor in circuit with the base of said first transistor; and a photoresistor in circuit with the base of said second transistor.

4. A water heater according to Claim

3, further comprising at least one resistor in circuit with said transistors, whereby the function of the change of contact points to said relay is effected by the change of bias of the base of the transistors.

5. A water heater according to Claim 3, wherein said phtoresistor changes its resistance by the illumination of said pilot burner and thus is effective to change the the state of contact points in said relay.

6. A water heater according to Claim 1, wherein the electric ignition circuit for igniting the main burner comprises a switch, a first transistor, and a relay in circuit with a source of electric power; a photoresistor and a second transistor in circuit with the base of said first transistor; and at least one resistor in circuit with the base of said second transistor.

7. A water heater according to Claim 6, wherein the function of change of contact points in said relay is effected by the change of bias of the base of said first transistor.

8. A water heater according to Claim 7, wherein the photoresistor changes its resistance by the illumination of said pilot burner and thus changes the bias state of the transistors and thus the state of contact points in said relay.