Premixing apparatus

Patent metadata

Field	Value
Publication number	US-10330312-B2
Application number	US-201715453470-A
Country	US
Kind code	B2
Filing date	Mar 8, 2017
Priority date	Mar 28, 2016
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

A premixing apparatus in which a downstream end of a gas supply passage having interposed therein a flow control valve is connected to a gas suction section disposed in an air supply passage on an upstream side of a fan. The premixing apparatus has: a butterfly valve as an air resistance changeover device for changing over, between high and low, a ventilation resistance in that section of the air supply passage which is on the upstream side of the gas suction section; and a gas resistance changeover device for changing over, between high and low, a ventilation resistance in that section of the gas supply passage which is on the downstream side of the flow control valve. Wind noises at the time of closing the butterfly valve can be prevented. For that purpose, in that section of the air supply passage which is on the upstream side of the gas suction section, an inner tube containing therein the butterfly valve is disposed while leaving a clearance to an inner circumferential wall surface of the air supply passage. A subsidiary passage which is parallel with a main passage inside the inner tube is constituted by the clearance between the inner circumferential wall surface of the air supply passage and an outer peripheral surface of the inner tube.

First claim

What is claimed is:

1. A premixing apparatus for mixing fuel gas with air to supply thus obtained air-fuel mixture, through a fan, to a burner,
in which a downstream end of a gas supply passage having interposed therein a flow control valve for supplying fuel gas is connected to a gas suction section disposed in an air supply passage on an upstream side of the fan, the premixing apparatus comprising:
an air resistance changeover device for changing over, between high and low, a ventilation resistance in that section of the air supply passage which is on an upstream side of the gas suction section; and
a gas resistance changeover device for changing over, between high and low, a ventilation resistance in that section of the gas supply passage which is on the downstream side of the flow control valve,
wherein the air resistance changeover device is constituted by a butterfly valve rotatably disposed in that section of the air supply passage which is on an upstream side of the gas suction section,
wherein in that section of the air supply passage which is on the upstream side of the gas suction section, an inner tube containing therein the butterfly valve is disposed while leaving a clearance to an inner circumferential wall surface of the air supply passage, and;
that a subsidiary passage which is parallel with a main passage inside the inner tube is constituted by the clearance between the inner circumferential wall surface of the air supply passage and an outer peripheral surface of the inner tube, and the main passage and the subsidiary passage supply air to the gas suction section.

2. The premixing apparatus according to claim 1 , where that half part of the butterfly valve which displaces in the upstream direction of the main passage when the butterfly valve is rotated from the closed posture at right angles to the longitudinal direction of the main passage into the opened posture in parallel with the longitudinal direction of the main passage is defined as a first-half part, and where that half part of the butterfly valve which displaces in the downstream direction of the main passage is defined as a second-half part,
wherein that peripheral corner portion of the side surface of the first-half part which faces the downstream direction of the main passage in the closed posture, and that peripheral corner portion of the side surface of the second-half part which faces the upstream direction of the main passage in the closed posture are both formed into rounded shapes.

3. The premixing apparatus according to claim 1 , where that half part of the butterfly valve which displaces in the upstream direction of the main passage when the butterfly valve is rotated from the closed posture at right angles to the longitudinal direction of the main passage into the opened posture in parallel with the longitudinal direction of the main passage is defined as a first-half part, and where that half part of the butterfly valve which displaces in the downstream direction of the main passage is defined as a second-half part,
wherein the inner tube further comprises a communication section for bringing the main passage and the subsidiary passage into communication with each other, the communication section being positioned on the upstream side of the butterfly valve in its closed posture and also being positioned on the side of the first-half part.

4. The premixing apparatus according to claim 1 , further comprising a Venturi section disposed in that section of the air supply passage which is adjacent to the upstream side of the gas suction section, the Venturi section being smaller in diameter than that section of the air supply passage which is provided with the inner tube,
wherein the inner circumferential wall surface of that section of the air supply passage which lies between the subsidiary passage and the Venturi section is formed into a tapered surface that is reduced in diameter toward the Venturi section.

Assignees

• Rinnai Kk

Inventors

• Shimazu Tomoyuki
• Miyata Mitsuru

Classifications

• F23K5/002 Primary

  Gaseous fuel · CPC title

• F23D14/62

  Mixing devices; Mixing tubes · CPC title

• F23D14/06 Primary

  with radial outlets at the burner head · CPC title

• F23N1/027 Primary

  using mechanical means · CPC title