WO2001031257A1

WO2001031257A1 - Gas valve having a regulator with independent minimum and maximum adjustments

Info

Publication number: WO2001031257A1
Application number: PCT/US1999/028982
Authority: WO
Inventors: Bernard Taylor Brown; Preston Robert Arnsperger; Patrick Stephen Bauman
Original assignee: Emerson Electric Co.
Priority date: 1999-10-27
Filing date: 1999-10-27
Publication date: 2001-05-03
Also published as: AU2476900A

Abstract

An improved device for adjusting the maximum and minimum set points for a gas valve with an integral modulating solenoid where the device consists of a jackscrew and arm for the maximum set point control and a jackscrew and arm for the minimum set point control, where the modulating solenoid has a shaft with a flange and the arms mechanically limit motion of the shaft by engaging the flange on the shaft.

Description

Gas Valve Having a Regulator With Independent Minimum and Maximum Adjustments

Field of the Invention

This invention relates to gas valves, and in particular to gas valves having adjustable minimum and maximum outlet pressure set point controls. Background of the Invention

Gas valves, such as those used in gas appliances such as furnaces and water heaters, typically include a regulator to "regulate" or control the outlet pressure from the valve more or less independently of the inlet pressure to the valve. These regulators are typically diaphragm type regulators such as those disclosed in U.S. Patent No. 3,843,049, issued 10/1974 to Baysinger; and No. 4,932,430, issued 6/1990 to Fernstrom, incorporated herein by reference. These regulators are usually adjustable by changing the biasing pressure on the diaphragm. One way of accomplishing this is with a solenoid that selectively compresses a spring acting on the diaphragm in the regulator. In this arrangement it is still desirable to be able to set the minimum and maximum outlet pressure set points so that these pressures are appropriate for the particular application.

In the gas valves previously available, setting the minimum and maximum outlet pressure set points was cumbersome and time consuming. In some valve constructions, adjustments of the minimum or maximum set points involved a complicated routine of energizing, adjusting and deenergizmg the solenoid m a particular order. In some valves the adjustment controls were on different faces of the valve. These problems are exacerbated by the coarseness of the available adjustment mechanisms, which made it difficult to accurately set the minimum and maximum set points. In other valve constructions, the adjustments were not independent, and adjustment of one setting might require readjustment the other setting. Even though such adjustments were typically performed m a factory setting when the valve was installed m some appliance, the adjustment was still unnecessarily difficult and complicated. Summary of the Invention

The gas valve of the present invention provides a variable regulated pressure output with easily adjusted minimum and maximum pressure set point mechanisms. Generally, the gas valve includes a diaphragm-type regulator with a biasing spring and a solenoid for varying the force applied by the spring on the diaphragm to adjust the outlet pressure. In accordance with this invention, adjustable minimum and maximum set points are provided for the solenoid. A first adjustable device engages the shaft of the solenoid to adjustably limit its motion in a first direction thereby establishing the minimum outlet pressure, and a second adjustable device engages the shaft of the solenoid to adjustably limit ts motion m a second direction thereby establishing the maximum outlet pressure. These two devices comprise jack screws with arms threadedly mounted thereon for engaging the solenoid shaft. The jack screws are arranged adjacent to each other so that both adjustments (the minimum and the maximum) can be conveniently made from one side. The threads on the jack screws and arms are such that they provide fine adjustment of the minimum and maximum. The apparatus permits independent and precision setting while providing access and ease of adjustment for the installation and service technician.

While many of the principal advantages and features of the present invention have been explained above, these and other features and advantages will be m part apparent and m part pointed out below.

Brief Description of the Drawings

Fig. 1 is a perspective view of a conventional gas valve; Fig. 2 is a vertical, longitudinal cross-sectional view of the gas valve taken along the plane of line 2-2 m Fig. 1 ; F g. 3 is a vertical cross-sectional view of a prior art regulator with minimum and maximum adjustment devices; Fig. 4 is a perspective view of a gas valve constructed according to principles of this invention;

Fig. 5 is a top plan view of the gas valve of the invention; Fig. 6 is a horizontal cross-sectional view of the gas valve taken along the plane of line 6-6 in Fig. 4;

Fig. 7 is a vertical cross-sectional view of the gas valve taken along the plane of line 7-7 in Fig. 5; and

Fig. 8 is a vertical cross-sectional view of the gas valve taken along the plane of line 8-8 in Fig. 5.

Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

Detailed Description of the Invention

A prior art gas valve construction is indicated generally as 20 in Figs. 1-3. The gas valve 20 comprises a valve housing 22, an inlet 24, an outlet 26, and a valve passage 28 through the valve housing between the inlet and outlet (indicated by the series of arrows in Fig. 2) . There is a valve seat 30 in the valve passage 28, and a valve member 32 operated by a diaphragm 34 moves relative to the valve seat 30 to control the flow through the valve passage 28. The diaphragm 34, and thus the valve member 32, move in response to a pressure differential across the diaphragm, and thus serve to regulate the outlet pressure of valve 20. The pressure across the diaphragm 34 can be regulated with a regulator to adjust the outlet pressure of the valve 20. The regulator opens and closes a passage 36 communicating with one side of the diaphragm 34 to control the pressure on that side of the diaphragm. An example of such a prior art regulator 40 is shown in Fig. 3. The regulator 40 includes a regulator diaphragm 42 that selectively seats over passage 36 to close the passage. The regulator diaphragm 42 is biased against the seat with a spring 44. A solenoid 46 controls the degree of compression of the spring 44, and thus the biasing force applied to the regulator diaphragm 42. One end of the spring 44 engages the regulator diaphragm 42, and the other end of the spring is engaged by the shaft 48 of the solenoid 46. Changing the electrical current supplied to the coil 49 changes the position of the shaft 48, and thus the compression of the spring 44. The greater the force applied to the regulator diaphragm 42, the higher the pressure on the one side of the diaphragm 34, and consequently the higher the gas outlet pressure of the gas valve 20. Similarly, the lower the force applied to the regulator diaphragm 42, the lower the pressure on the one side of the diaphragm 34, and consequently the lower the gas outlet pressure of the gas valve 20. The minimum and maximum pressure of the gas valve, is thus dependant on the minimum and maximum biasing force applied to the regulator diaphragm 42 by the spring 44, and this is in turn dependent upon the position of the shaft 48 of the solenoid 46.

Regulator 40 thus includes minimum and maximum set point adjustment mechanism 50 for limiting the movement of shaft 48 away from and toward the regulator diaphragm 42 to set the minimum and maximum operating pressure of the gas valve 20. The minimum and maximum set point adjustment mechanism 50 comprises sleeve 52 having a first end 54 oriented toward the regulator diaphragm 42, and a second end 56 oriented away from the regulator diaphragm 42. The sleeve 52 is disposed in the core of the solenoid 46, and at least a portion of the shaft 48 of the solenoid is within the sleeve 52. The exterior of the sleeve 52 has threads 58 that mate with threads 60 on the inside of the core of the solenoid 46, so that the sleeve can be threaded into and out of the core of the solenoid, toward and away from the regulator diaphragm 42. The second end 56 of the sleeve 52 has a shaped section 62 (for example hexagonally shaped) to facilitate threading the sleeve into and out of the solenoid 46. The first end 54 of the sleeve 52 has an internal shoulder 64 formed therein. The shoulder 64 engages a projecting flange 66 on the shaft 48 to limit the movement or travel of the shaft toward the regulator diaphragm 42. The inside of the sleeve 52 has threads 68 into which a threaded stop screw 70 is threaded. The end of the screw 70 inside the sleeve forms a stop for engaging the end of the shaft 48 of the solenoid 46, thereby limiting the movement or travel of the shaft away from the regulator diaphragm 42, and setting the minimum pressure of the gas outlet valve 20. The opposite end of the screw 70 is configured to be engaged by a tool, such as a screw driver, to drive the screw 70 into or out of the sleeve 52.

While the minimum and maximum set point adjustment mechanism 50 does allow the minimum and maximum operating pressure set points to be set, its operation is not without some difficulty. First, turning the sleeve 52 to change the maximum operating pressure set point causes the screw 70 to move as well, requiring the screw 70 to be moved to reestablish the desired minimum each time the maximum is changed. Second, the turning of the screw 70 to change the minimum operating pressure set point sometimes causes the entire sleeve to turn and change the maximum operating pressure set point. Thus, the sleeve 52 generally must be held against rotation as the screw 70 is turned. Finally, threads on the exterior and interior are very coarse, making fine pressure adjustments difficult and time consuming.

The gas valve 20' of the present invention is similar in construction to gas valve 20, and corresponding reference numerals identify corresponding parts but instead of regulator 40, valve 20' includes a regulator 100, shown m Figs. 4-8 for regulating the pressure across the diaphragm 34 to adjust the outlet pressure of the valve 20. The regulator 100 opens ana closes a passage 36 communicating with one side of the diaphragm to control the pressure on that side of the diaphragm. The regulator 100 includes a housing 102 and a regulator diaphragm 104 that selectively seats over passage 36 to close the passage. The regulator diaphragm 104 is biased against the passage 36 with a spring 106. A solenoid 108 controls the degree of compression of the spring 106, and thus the biasing force applied to the regulator diaphragm 104. One end of the spring 106 engages the regulator diaphragm 104, and the other end of the spring is engaged by the shaft 110 of the solenoid 108. The solenoid 108 is secured on the housing 102 with a bracket 112. The shaft 110 extends through a bushing 114. A cap 116 closes the end of the solenoid 108, providing a space for the shaft 110 to travel.

Changing the electrical current supplied to the coil 112 of the solenoid 108 changes the position of the shaft 110, and thus the compression of the spring 106. The greater the force applied to the regulator diaphragm 104, the higher the pressure on the one side of the diaphragm 34, and consequently the higher the gas outlet pressure of the gas valve 20' . Similarly, the lower the force applied to the regulator diaphragm 104, the lower the pressure on the one side of the diaphragm 34, and consequently the lower the gas outlet pressure of the gas valve 20' . The minimum and maximum pressure of the gas valve 20' is thus dependant on the minimum and maximum biasing force applied to the regulator diaphragm 102 by the spring 106, and this is in turn dependent upon the position of the shaft 110 of the solenoid 108.

Regulator 100 thus includes minimum set point adjustment mechanism 118 for limiting the movement of shaft 110 away from the regulator diaphragm 104 to set the minimum operating pressure, and maximum set point adjustment mechanism 120 for limiting the movement of shaft 108 toward the regulator diaphragm 104 to set the maximum operating pressure. The minimum set point adjustment mechanism 118 comprises a jack screw 122 mounted in the housing 102 of the regulator 100 to rotate. The head 124 projects from the housing 102, and has a recess therein that can be engaged by, and turned with a tool, for example a screw driver. An arm 126 is threadedly mounted on the jack screw 122, and is constrained against rotation by the housing 102. Thus rotation of the jack screw 122 causes the arm 126 to translate. As shown in Fig. 6, the arm 126 projects sufficiently to engage the face 128 of a flange 130 on the shaft 110 of the solenoid 108 that faces away from the regulator diaphragm 104, to limit the travel of the shaft away from the regulator diaphragm.

The maximum set point adjustment mechanism 120 comprises a jack screw 132 mounted in the housing 102 of the regulator 100 to rotate. The head 134 projects from the housing 102, and has a recess therein that can be engaged by, and turned with a tool, for example a screw driver. An arm 136 is threadedly mounted on the jack screw 132, and is constrained against rotation by the housing 102. Thus rotation of the jack screw 132 causes the arm 136 to translate. The arm 136 projects sufficiently to engage the face 138 of flange 130 on the shaft 110 of the solenoid 108 that faces the regulator diaphragm 104, to limit the travel of the shaft toward the regulator . The heads 124 and 134 of the jack screws 122 and 132 are positioned on the same side of the regulator housing, adjacent to each other so that the minimum and maximum can be conveniently set. The jack screws 122 and 132 allow the minimum and maximum pressures to be easily set with a screw driver. Each of the adjustment mechanisms 118 and 120 operate independently of the other so that the minimum pressure can be set independently of the maximum, eliminating the need to readjust one of values when the other is adjusted. The threads on the jack screws and the arms are such that one complete rotation of the screws does not change the set point pressure by more than about 4 mbar to allow for accurate adjustment .

Claims

What is claimed:

1. A gas valve comprising: a body having an inlet, an outlet, and a valve passage therebetween; a valve member for controlling flow through the valve passage; a variable regulator for regulating the outlet pressure of the valve, the variable regulator including a diaphragm whose movement regulates the operation of the valve member, the regulator further comprising a spring biasing the diaphragm, and a solenoid having a moveable shaft whose movement changes the compression of the spring to change the biasing force on the diaphragm and thereby the outlet pressure of the valve; a minimum set point adjustment mechanism for engaging the shaft to limit its movement m a first direction and thereby set a minimum outlet pressure of the valve, the minimum set point adjustment mechanism comprising a threaded jack screw and an arm threaded on the jack screw to translate upon rotation of the jack; and a maximum set point adjustment mechanism for engaging the shaft to limit its movement m a second direction and thereby set a maximum outlet pressure of the valve, the maximum set point adjustment mechanism comprising a threaded ack screw and an arm threaded on the jack screw to translate upon rotation of the jack screw.

2. The gas valve according to claim 1 wherein each of the jack screws has a head with a recess for engaging a tool by which the jack screw can be rotated, and wherein the heads of the jack screws are on the same side of the valve so that the maximum and minimum set points can be set from the same side of the valve.

3. The gas valve according to claim 1 wherein the shaft of the solenoid has a flange thereon, and wherein the arm of the minimum set point adjustment mechanism engages one side of the flange and the maximum set point adjustment mechanism engages the other side of the flange.

4. A maximum and a minimum set point adjustment mechanism for a modulating solenoid on a gas valve, the modulating solenoid including a shaft that moves m first and second directions in a coil, the minimum and maximum set point adjustment mechanism comprising; a maximum set point jack screw and a maximum set point arm threaded on the maximum set point ack screw, and extending therefrom sufficiently to engage the shaft, and limit the movement of the shaft m first direction and thereby establish a maximum set point, the maximum set point arm translating upon rotation of the maximum set point jack screw to thereby change the maximum set point; and a minimum set point jack screw and a minimum set point arm threaded on the minimum set point jack screw, and extending therefrom sufficiently to engage the shaft, and limit the movement of the shaft in the second direction and thereby establish a minimum set point, the minimum set point arm translating upon rotation of the minimum set point jack screw to thereby change the minimum set point.

5. The maximum and minimum set point adjustment mechanism of claim 4 wherein: the maximum set point arm and the minimum set point arm are independently positionable .

6. The maximum and minimum set point adjustment mechanism of claim 5 wherein: the maximum set point jack screw and the minimum set point jack screw are rotatably secured in the gas valve.

7. The maximum and minimum set point adjustment mechanism of claim 7 further comprising a maximum set point arm guide in which the maximum set point arm translates as the maximum set point jack screw is rotated, and a minimum set point arm guide in which the minimum set point arm translates as the minimum set point jack screw is rotated.

8. The maximum and minimum set point adjustment mechanism of claim 7 wherein: the maximum set point arm guide is formed in the gas valve, and the minimum set point arm guide is formed in the gas valve.

9. The maximum and minimum set point adjustment mechanism of claim 8 further comprising a flange projection radially outwardly from the shaft of the solenoid, and wherein the maximum set point arm engages the flange to limit movement of the shaft in the first direction and wherein the minimum set point arm engages the flange to limit movement of the shaft in the second direction.

10. The maximum and minimum set point adjustment mechanism of claim 9 wherein the flange has oppositely facing first and second faces and wherein the maximum set point arm engages the first face of the flange to restrict movement of the shaft in the first direction, and the minimum set point arm engages the second face of the flange to restrict movement of the shaft in the second direction.

11. The maximum and minimum set point adjustment mechanism of claim 6 wherein: the maximum set point jack screw has a head for rotating the maximum set point jack screw and adjustably positioning the maximum set point arm, and minimum set point jack screw has a head for rotating the minimum set point jack screw to adjustably position the minimum set point arm.

12. The maximum and minimum set point adjustment mechanism of claim 11 wherein: the head of the maximum set point jack screw has a recess and the head of the minimum set point jack screw has a recess.

13. The maximum and minimum set point adjustment mechanism of claim 6 wherein: the maximum set point head and the minimum set point head are exposed on the same surface of the valve.

14. The maximum and minimum set point adjustment mechanism of claim 6 wherein: one rotation of the maximum set point jack screw changes the maximum set point by no more than 4 mbar and one rotation of the minimum set point jack screw changes the minimum set point by no more than 4 mbar.