WO2004038270A1

WO2004038270A1 - Electronically-controlled variable pilot valve

Info

Publication number: WO2004038270A1
Application number: PCT/US2003/033745
Authority: WO
Inventors: Raymond A. Vincent; Randall Paul Schmitt
Original assignee: Masco Corporation
Priority date: 2002-10-24
Filing date: 2003-10-24
Publication date: 2004-05-06
Also published as: AU2003287196A1

Abstract

An electronically-controlled variable pilot valve (110) includes a variable force solenoid (150) and an armature (152) whose position is controlled by the solenoid. The variable force solenoid applies a force that is proportional to the signal level applied to the solenoid onto the armature (152). As a result, the position of the armature varies based on the applied signal level. A shaped extension (166) on the armature varies the size of a variable orifice between a pilot valve outlet (160) and the armature (152) based on the position of the armature. Thus, the armature position, and therefore the variable orifice size can be varied directly, allowing variable control of a main valve without being restricted by the operational limitations of conventional on/off pilot valves and without requiring direct control of the main valve.

Description

ELECTRONICALLY-CONTROLLED VARIABLE PILOT VALVE

TECHNICAL FIELD

The present invention relates to valve systems, and more particularly to a valve system having a main valve controlled by an electronically-controlled pilot valve.

BACKGROUND OF THE INVENTION

Naive systems may include a main valve and a pilot valve to control large fluid flow devices. To operate the main valve, the pilot valve may be opened or closed, thereby changing the pressure in the main valve to open and close the main valve.

Proportional valve systems have been proposed to provide closer control over the among of water flowing through the main valve. These systems often require a large amount of current to operate the main valve in a proportional manner

(e.g., by controlling a motor or other actuator to place the main valve in a desired position) and/or require mechanical means to move the main valve in a proportional manner. This often wastes power because high energy levels are needed to control relatively low fluid flows. Other systems propose controlling the pilot valve electronically to provide proportional control of the main valve. Pilot valves allow a large main valve to be controlled by operating a small valve, reducing the amount of energy required for valve control. Currently known pilot valve control systems, however, do not allow the pilot valve to act as a true proportional valve. Instead, the pilot valve is still fully open or fully closed based on, for example, the pulse width of a signal to a full- stroke solenoid that moves the pilot valve between its open and closed positions. The pilot valve is then "dithered," or rapidly opened and closed, to provide proportional control. The desired amount of fluid flow through the main valve may be controlled by pulse width modulation of the signal to the solenoid. However, this method still requires a great deal of energy because the full-stroke solenoid will constantly move the pilot valve between its fully open and fully closed positions; thus, the only way to maintain fluid flow at a selected level is to modulate the signal controlling the solenoid to move the pilot valve back and forth at different time intervals.

There is a desire for a variable pilot valve that can be opened and closed in a variable manner to control a variable main valve.

SUMMARY OF THE INVENTION The present invention is directed to an electronically-controlled variable pilot valve. In one embodiment, the pilot valve comprises a variable force solenoid and an armature whose position is controlled by the solenoid onto the armature. The variable force solenoid applies a force that is proportional to the signal level applied to the solenoid. As a result, the position of the armature varies based on the applied signal level.

The armature has an extension that extends into a pilot fluid path outlet and seats against it when the armature is in a closed position. The extension is shaped so that a variable orifice formed between the outlet and the armature changes size based on the position of the armature. In one embodiment, the extension has a tapered shape, such as a generally conical shape so that the variable orifice becomes proportionally larger as the armature is moved away from the pilot valve outlet. Thus, the armature position, and therefore the variable orifice size, can be varied directly, allowing variable control of a main valve without being restricted by the operational limitations of conventional on/off pilot valves and without requiring direct control of the main valve.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a representative diagram of a system incorporating a pilot valve according to one embodiment of the invention;

Figure 2 is a representative diagram of a pilot valve according to one embodiment of the invention in a fully closed position;

Figure 3 is a representative diagram of the pilot valve shown in Figure 2 in various partially open positions;

Figure 4 is a representative diagram of the pilot valve shown in Figure 2 in a fully open position. DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 is a representative diagram of a system incorporating a pilot valve 100 according to the invention. The pilot valve controls fluid (e.g., liquid, gas, etc.) flow in a pilot chamber 101 to control operation of a main valve 102.. The main valve 102 can be any known pressure-sensitive valve (e.g., diaphragm, piston, etc.) whose operation can be influenced by a pilot valve 100. The main valve 102 controls fluid flow through a main fluid path 104. The pilot valve 100 is fluidically coupled to a main valve 102 to control its operation. Movement of the pilot valve changes the pressure across the main valve, causing the main valve to vary its position between open and closed positions. In the illustrated embodiment, the main valve 102 is variable and can be opened partially between the fully open and fully closed positions to provide greater fluid flow control in the main fluid path 104. More particularly, the position of the main valve 102 is variable due to the variable pilot valve 100 and not to direct control over the main valve 102 itself. Referring to Figure 2, the pilot valve 100 comprises a variable force solenoid having a coil 150 and an armature 152 that is movable in the coil 150. The armature 152 is biased in a closed position by a resilient member 154, such as a spring, to close a pilot fluid path 156 having an inlet 158 and an outlet 160. Both the pilot fluid path inlet 158 and outlet 160 are fluidically coupled to the main fluid path 104. When the armature 152 is in the fully closed position, it seats against the pilot fluid path outlet 160. In the illustrated embodiment, an optional valve seat 162 around the outlet 160 is included to improve a fluid-tight seal against the armature 152. Other sealing structures may be used without departing from the scope of the invention.

Operation of the variable force solenoid 150 is controlled by a processor 163, which generates a signal corresponding to a desired amount of force to be exerted onto the armature 152. As shown in Figure 3, the solenoid 150 exerts a variable force on the armature 152 against the spring biasing force of the resilient member 154, changing the position of the armature 152. When the armature 152 moves toward an open position, it forms a variable orificel64 between the armature 152 and the pilot fluid path outlet 160 through which fluid can flow. Because the size of the variable orifice 164 controls the pressure inside the main valve 102, the main valve's position is controlled by the position of the armature 152. More particularly the armature 152 is shaped so that the position of the armature 152 in the pilot fluid flow path 156 changes the size of the variable orifice 164. To do this, the armature 152 has an extension 166 that is shaped so that different armature positions correspond to different variable orifice sizes, and therefore different main valve 102 positions as the pressure between the pilot valve 100 and the main valve 102 reach equilibrium. In the illustrated embodiment, the extension 166 is tapered so that the variable orifice 164 varies proportionally to the signal applied to the solenoid 150; however, any other shape may be used. For example, an extension with a scalloped profile also provides good control over the variable orifice size. In this example, raising the signal level applied to the solenoid 150 will increase the force applied to the armature 152 and pull the armature 152 further away from the outlet 160, thereby increasing the size of the variable orificel64. As shown in Figure 3, the position of the armature 152 will dictate how much fluid flows through the pilot fluid flow path 156 and therefore how much the main valve 102 will move within the main fluid flow path 104. For example, the variable orifice size may be proportional to the signal level applied to the solenoid 150, causing the main valve 102 to move to a position that causes the size of the main valve fluid path 104 to be proportional to the signal level as well.

If a predetermined maximum signal level is applied to the solenoid 150, as shown in Figure 4, the armature 152 and the extension 166 lift completely away from the outlet 160 to allow the maximum amount of fluid flow to pass through the pilot fluid flow path 156. As shown in Figure 4, the extension 166 does not block any portion of the outlet 160. In this case, the unfettered fluid flow in the pilot fluid flow path 156 caused by the fully open pilot valve 100 will change the pressure in the main valve 102 to cause the main valve 102 to move to a fully open position.

By creating a tapered extension on the armature, the pilot valve 100 provides a simple relationship between the applied signal, the armature position, and the variable orifice size. As a result, the tapered extension provides a predictable, direct relationship between the signal applied to the pilot valve 100 and the position of the main valve 102.

The processor 163 may also receive signals from a sensor 168 disposed in the main fluid path 104. The sensor 168 can be any type of sensor, such as a temperature sensor or a flow rate sensor. By forming a feedback loop in this manner, the position of the armature 152 may be controlled based on feedback from the main valve 102, allowing the pilot valve 100 to continuously adjust itself to maintain a selected pressure or flow rate as these characteristics change in the main fluid path 104. For example, the processor 163 may be programmed so that the variable orifice size is proportional to a coefficient of velocity of fluid flowing in the main fluid path 104. The variability of the pilot valve 100 allows these adjustments to take place while keeping the structure and control of the pilot valve 100 simple.

The inventive variable pilot valve therefore allows indirect variable control of a main valve via direct control over the pilot valve. By providing a variable pilot valve rather than a conventional on/off pilot valve to provide variable control over the main valve, the invention offers a simple valve system that can provide fine- tuned main valve control using small electronic signals. This is true even if the main valve is large, improving energy-efficiency of the overall valve system. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby.

Claims

1. A variable pilot valve, comprising: a coil; an armature, wherein the coil and the armature form a variable force solenoid and wherein a position of the armature is variable based on an input signal level applied to the coil; and an extension extending from the armature into a pilot fluid flow outlet, the extension having a shape that changes a variable orifice size between the extension and the outlet when the position of the armature varies.

2. The pilot valve of claim 1, wherein the extension is generally tapered.

3. The pilot valve of claim 1, wherein the extension has a scalloped profile.

4. The pilot valve of claim 1, wherein the movement of the armature varies the variable orifice size so that the variable orifice size is proportional to the input signal level.

5. The pilot valve of claim 1, further comprising a sensor that senses a fluid flow in a main valve fluid path, wherein the movement of the armature varies the variable orifice size so that the variable orifice size is proportional to a coefficient of velocity corresponding to the fluid flow.

6. The pilot valve of claim 1, further comprising a resilient member that applies a biasing force to the armature.

7. A valve system, comprising: a variable main valve that controls fluid flow in a main valve fluid path; and a variable pilot valve that controls fluid flow in a pilot valve fluid path having a pilot fluid flow inlet fluidically coupled to the main valve fluid path, the variable pilot valve including a coil, an armature, wherein the coil and the armature form a variable force solenoid and wherein a position of the armature is variable based on an input signal level applied to the coil, and an extension extending from the armature into the pilot fluid flow outlet, the extension having a shape that changes a variable orifice size between the extension and the outlet when the position of the armature varies.

8. The valve system of claim 7, wherein the extension in the armature is generally tapered.

9. The pilot valve of claim 7, wherein the extension has a scalloped profile.

10. The valve system of claim 7, wherein the movement of the armature varies the variable orifice size so that the variable orifice size is proportional to the input signal level.

11. The valve system of claim 10, wherein a size of the main valve fluid path is proportional to the input signal level.

12. The valve system of claim 7, further comprising a resilient member that applies a biasing force to the armature.

13. The valve system of claim 7, further comprising a processor in communication with at least one of the variable pilot valve and the variable main valve, wherein the processor sends the input signal to the coil.

14. The valve system of claim 13, wherein the processor is in communication with both the variable pilot valve and the variable main valve

15. The valve system of claim 14, further comprising a sensor that senses a fluid flow in the main valve fluid path, wherein the processor generates the input signal to move the armature to vary the variable orifice size so that the variable orifice size is proportional to a coefficient of velocity corresponding to the fluid flow.