US 5,878,741 A · Differential pressure modulated gas valve for single stage combustion control

Abstract

An apparatus senses the pressure changes in a collector box or relief box of a furnace due to changing wind conditions, and adjusts the gas flow accordingly. The apparatus controls the main gas valve of the furnace through a regulator loop. The regulator loop has a first port that communicates with a chamber below the main diaphragm of the valve, and a second port that communicates with a chamber above the main diaphragm. The regulator includes two diaphragms linked rigidly. A feedback pressure channel is connected to the collector box or the relief box, at one end, and to a feedback pressure tap at the other end. An increase in wind at the furnace vent causes changes in pressure in the collector box and the relief box. This change in pressure is delivered to the feedback pressure tap. When the pressure at the feedback pressure tap increases, the top diaphragm and the bottom diaphragm both move upward. As the pair of diaphragms move upward, there is relatively more flow through the second port and relatively less through the first port, causing a pressure differential across the main diaphragm; a higher pressure then exists above the main diaphragm compared to the pressure below the main diaphragm. The main valve then moves toward the closed position. When the pressure at the feedback pressure tap decreases, the diaphragms move down. This causes relatively more flow through the first port and relatively less flow through the second, causing the valve to open.

Claims6

Dependent claims

A gas control valve for controlling gas flow to a burner of a furnace, the furnace having a draft inducer, a collector box, a relief box and a vent, the gas control valve comprising:

an inlet for receiving a flow of gas;
a main valve for controlling the flow of gas to the burner, having an inlet side and an outlet side in fluid communication with said inlet, said main valve having an open position and a closed position;
means for sensing changes in pressure at the vent;
and
means for moving said main valve in response to said means for sensing in a modulating manner such that an increase in pressure at said vent causes gas flow to decrease through said main valve and a decrease in pressure at said vent causes gas flow to increase through said main valve.

2 more elements

A gas control valve for controlling gas flow to a burner of a furnace, the furnace having a draft inducer, a collector box and a relief box, the gas control valve comprising:

an inlet for receiving a flow of gas;
a main valve for controlling the flow of gas to the burner, having an inlet side and an outlet side in fluid communication with said inlet, said main valve having an open position and a closed position;
means for moving said main valve;
a control loop in fluid communication with said inlet for receiving a portion of the flow of gas to said main valve;
a flow regulator;
a first diaphragm and a second diaphragm in said flow regulator defining a feedback chamber therebetween;
a feedback pressure tap in fluid communication with said feedback chamber and the relief box such that pressure changes in the relief box are transmitted to said feedback chamber;
said first diaphragm constructed with a larger area than the second diaphragm, said diaphragms are connected so they move in unison with each other, the diaphragms are constructed such that changes in pressure in said feedback chamber causes said first and second diaphragms to move;
and
means for controlling said main valve in response to movement of said first and second diaphragms such that an increase in pressure in said feedback chamber cause said main valve to move in the closed direction and a decrease in pressure in said feedback chamber causes said main valve to move in the open direction.

7 more elements

A gas control valve for controlling gas flow to a burner of a furnace, the furnace having a draft inducer, a collector box and a relief box, the gas control valve comprising:

an inlet for receiving a flow of gas;
a main valve for controlling the flow of gas to the burner, having an inlet side and an outlet side in fluid communication with said inlet, said main valve having an open position and a closed position;
means for moving said main valve;
a control loop in fluid communication with said inlet for receiving a portion of the flow of gas to said main valve;
a flow regulator;
a first diaphragm and a second diaphragm in said flow regulator defining a feedback chamber therebetween;
a feedback pressure tap in fluid communication with said feedback chamber and the collector box such that pressure changes in the collector box are transmitted to the feedback chamber;
said first diaphragm constructed with a larger area than the second diaphragm, said diaphragms are connected so they move in unison with each other, the diaphragms are constructed such that changes in pressure in said feedback chamber cause said first and second diaphragms to move;
and
means for controlling said main valve in response to movement of said first and second diaphragms such that an increase in pressure in said feedback chamber causes said main valve to move in the closed direction and a decrease in pressure in said feedback chamber causes said main valve to move in the open direction.

7 more elements

Dependencies are inferred from the claim text.

Differential pressure modulated gas valve for single stage combustion control

Life of this patent

Differential pressure modulated gas valve for single stage combustion control

Life of this patent

Abstract

Claims6