# US 10,309,687 B2 · Combustion control system of gas water heater or wall-hanging boiler and control method thereof

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- Number: US 10,309,687 B2
- Document ID: US10309687B2
- Status: Granted
- Kind: B2
- Application number: 15/658,838
- Filed: 2017-07-25
- Published: 2017-11-23
- Granted: 2019-06-04
- Earliest claimed: 2015-01-26
- Assignees: A. O. Smith Corporation
- Applicants: A. O. Smith Corporation
- Inventors: Bu Qiu; Dayan Bi; Zhi Li; Maohu Cai
- Web page: https://patentgrep.com/patent/US10309687B2

## CPC

- F24H 9/2042: {Preventing or detecting the return of combustion gases}
- F23J 13/00: Fittings for chimneys or flues (side-supporting means for chimney stacks E04H12/20; ladders permanently attached to chimneys E06C9/00; draught-inducing apparatus associated with chimneys or flues F23L17/00; tops for chimneys, terminals for flues F23L17/02)
- F23N 3/002: {using electronic means (F23N3/02 - F23N3/08 take precedence)}
- F23N 3/082: {using electronic means}
- F24H 1/205: {with furnace tubes}
- F24H 15/112: Preventing or detecting blocked flues
- F24H 15/215: before heating
- F24H 15/238: Flow rate
- F24H 15/242: Pressure
- F24H 15/281: Input from user
- F24H 15/35: Control of the speed of fans
- F23N 2225/04: pressure
- F23N 2233/04: with variable speed
- F24H: FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL (steam generation F22)
- F23J: REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES (combustion apparatus for consuming smoke or fumes, e.g. exhaust gases, F23G7/06)
- F23N: REGULATING OR CONTROLLING COMBUSTION (control devices specially adapted for combustion apparatus in which combustion takes place in a fluidised bed of fuel or other particles F23C10/28; condition responsive controls for regulating combustion in domestic stoves with open fires for solid fuel F24B1/187)

## Abstract

The embodiments of the present application disclose a combustion control system of a gas water heater or wall-hanging boiler, and a control method thereof. The system comprises: a flue gas channel consisted of a combustor, a heat exchanger and a stepless speed regulating fan and a smoke tube, which are connected sequentially; a control unit connected to a signal input end of the stepless speed regulating fan; a wind pressure sensor assembly that detects a pressure signal upstream of an impeller of the stepless speed regulating fan, a signal output end of the wind pressure sensor assembly being connected to the control unit; the control unit comprising a storage for storing a correspondence relationship between the pressure signal upstream of the stepless speed regulating fan and a thermal load of the combustor, and a controller that controls operation of the stepless speed regulating fan according to the correspondence relationship. The present application further regulates the rotational speed of the stepless speed regulating fan by detecting the pressure signal upstream of the impeller of the stepless speed regulating fan, thereby achieving a better wind-resistant performance of the present application.

## Claims

### Claim 1

A combustion control system of a gas water heater or a wall-hanging boiler, characterized by comprising:
a flue gas channel consisted of a combustor, a heat exchanger and a stepless speed regulating fan and a smoke tube which are connected sequentially;
a control unit connected to a signal input end of the stepless speed regulating fan;
a wind pressure sensor assembly that detects a pressure signal upstream of an impeller of the stepless speed regulating fan, a signal output end of the wind pressure sensor assembly being connected to the control unit;
the control unit comprising a storage for storing a correspondence relationship between the pressure signal upstream of the impeller of the stepless speed regulating fan and a thermal load of the combustor, and a controller that controls operation of the stepless speed regulating fan according to the correspondence relationship,
wherein a smoke tube outlet of the smoke tube is provided with a wind-proof cap that opens and closes along with a change of pressure inside and outside the smoke tube outlet.

### Claim 2 (depends on 1)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 1, characterized in that: an area of the wind-proof cap is larger than an area of the smoke tube outlet.

### Claim 3 (depends on 2)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 2, characterized in that: the wind-proof cap has a turn-up that covers part of the smoke tube.

### Claim 4 (depends on 2)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 2, characterized in that: the flue gas channel also includes a transitional smoke tube accommodating the wind-proof cap, the transitional smoke tube being connected adjacent to an outer surface of the smoke tube outlet.

### Claim 5 (depends on 1)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 1, characterized in that: the wind pressure sensor assembly includes a piezometer tube and a wind pressure sensor; one end of the piezometer tube is connected to the wind pressure sensor, while the other end thereof is a pressure measuring end.

### Claim 6 (depends on 5)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 5, characterized in that: the wind pressure sensor is provided at a position outside the flue gas channel and higher than a positon of the pressure measuring end.

### Claim 7 (depends on 5)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 5, characterized in that: a cavity lower than the pressure measuring end is connected between the piezometer tube and the wind pressure sensor, and a cross sectional area of the cavity is larger than a cross sectional area of the piezometer tube.

### Claim 8 (depends on 5)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 5, characterized in that: a thermal insulating apparatus is provided between the wind pressure sensor and the flue gas channel.

### Claim 9 (depends on 5)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 5, characterized in that: the pressure measuring end is provided between the stepless speed regulating fan and the combustor.

### Claim 10 (depends on 5)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 5, characterized in that: the pressure measuring end extends from an air inlet of the stepless speed regulating fan into an interior of a fan shell of the stepless speed regulation fan.

### Claim 11 (depends on 1)

The combustion control system of a gas water heater or a wall-hanging boiler according to claim 1, characterized in that: the correspondence relationship between the pressure signal upstream of the stepless speed regulating fan and the thermal load of the combustor is stored in the storage in the form of a data table, which data table records the pressure signal upstream of the stepless speed regulating fan and the thermal load of the combustor correspondingly.

### Claim 12 (depends on 1)

A control method for a combustion control system of a gas water heater or a wall-hanging boiler according to claim 1, comprising the following steps:
the controller obtains a thermal load of the combustor according to an operation condition of the gas water heater or wall-hanging boiler, and obtains a pressure signal upstream of the stepless speed regulating fan corresponding to the thermal load based on the correspondence relationship in the storage, and uses the pressure signal as a target pressure signal;
the controller obtains a current pressure signal upstream of the stepless speed regulating fan detected by the wind pressure sensor;
the controller controls a rotational speed of the stepless speed regulating fan, and adjusts the current pressure signal to approach the target pressure signal.

### Claim 13 (depends on 12)

The control method for a combustion control system of a gas water heater or a wall-hanging boiler according to claim 12, characterized in that: a smoke tube outlet of the smoke tube is provided with a wind-proof cap that opens and closes along with a change of pressure inside and outside the smoke tube outlet, and when the wind-proof cap tends to close or is closed, the controller controls the stepless speed regulating fan to increase the rotational speed.

### Claim 14 (depends on 12)

The control method for a combustion control system of a gas water heater or a wall-hanging boiler according to claim 12, characterized in that: the correspondence relationship between the pressure signal upstream of the stepless speed regulating fan and the thermal load of the combustor is |Δf|∝|ΔQ|, wherein Δf is an amount of change of the pressure signal upstream of the stepless speed regulating fan, and ΔQ is an amount of change of the thermal load of the combustor.

### Claim 15 (depends on 12)

The control method for a combustion control system of a gas water heater or a wall-hanging boiler according to claim 12, characterized in that, the correspondence relationship includes a predefined function that expresses a logical relationship between the pressure signal and the thermal load, the predefined function has a predefined parameter, and the predefined parameter represents a reference value of the wind pressure sensor; a smoke tube outlet of the smoke tube is provided with a wind-proof cap that opens and closes along with a change of pressure inside and outside the smoke tube outlet, the wind-proof cap covers the smoke tube outlet before the stepless speed regulating fan is operated, and the controller obtains a current pressure signal of the wind pressure sensor assembly as the reference value.

### Claim 16 (depends on 12)

A control method for a combustion control system of a gas water heater or a wall-hanging boiler according to claim 12, characterized in that, in the step of obtaining the thermal load according to the operation condition, the operation condition includes a set temperature, an actual water flow and an inflow water temperature.