UNLOADER VALVE FOR SPRAY GUNS

• US 3,729,018 A
• Filed: 07/06/1971
• Issued: 04/24/1973
• Est. Priority Date: 07/06/1971
• Status: Expired due to Term

• Current Assignee: Ted Lee Butterfield
• Original Assignee: Ted Lee Butterfield
• Inventors: Butterfield, Ted Lee
• Primary Examiner(s): Klinksiek, Henry T.
• Assistant Examiner(s): Miller, Robert J.
• Application Number:
  US05/160,014
• Time in Patent Office: 658 Days
• Field of Search: 137/501,475,478,614.2,499,501,614.2,469 437/469,614.17,493 251/120,117,121,122
• US Class Current: 137/469
• CPC Class Codes: F16K 17/082 with piston
• CPC Class Codes: Y10T 137/7738 Pop valves
• CPC Class Codes: Y10T 137/7788 Pressures across fixed choke
• CPC Class Codes: Y10T 137/88054 Direct response normally closed valve limits direction of flow

Abstract

An unloader type valve for spray guns supplied from pumps to limit operating pressures of the pump when the spray gun is stopped. The valve utilizes an adjustable spring to select pressure forces for opening the valve and a variable flow passage from the valve to an outlet when the valve is open, the allowing matching of the valve to the precise operating pressures and flow rates in spray gun and pumping system installations.

Claims

1. An unloader valve defined by a hollow valve body having an inlet and an outlet leading to an interior working space in the body, a pressure operated piston movably mounted in the interior space of said body, said valve body having a valve seat of smaller cross-sectional area than said piston and formed around said inlet passage, said piston including a reduced portion adapted to engage said seat to close off flow through said body, said valve body including passage means communicating the space between said seat and said piston, when said piston is away from said seat, with an outlet from said body, adjustable means for varying the flow area through said passage means, a spring positioned between said piston and an abutment in said valve body to exert closing forces on said piston, and means for adjusting the spring pressure to adjust the closing forces exerted by said spring on said piston to thereby vary the pressure force in said inlet passage necessary to move said piston away from said seat, the entire cross-sectional area of said piston being subjected to the pressure in said space when said piston is away from said seat to thereby hold the piston away from said seat as long as the total force due to pressure in said space exceeds the closing forces of said spring.

2. The structure of claim 1 wherein said passage means is defined by a passage positioned laterally of said interior space and communicating with said space on opposite sides of said piston.

3. The structure of claim 2 wherein said adjustable means for regulating flow is defined by a flow restricting element, and said element is variably positionable across a portion of said passage means by an adjusting screw carried by said body.

4. The structure of claim 3 wherein said element is variably positionable across a portion of said passage extending transversely to the axis of said piston and said passage has a shoulder positioned over said portion and limiting movement of said element over said portion to a position providing a small flow space through said portion.

5. The structure of claim 1 wherein said means for adjusting spring pressure includes a movable abutment engaging one end of said spring, said abutment being axially movable against said spring by a screw threaded in said body.

6. The structure of claim 5 wherein said passage means is defined by a passage in said body and positioned laterally of said interior space, said outlet being defined by a bore opening into said space on the side of said piston opposite to the inlet side, said passage communicating with said space by a first bore positioned transversely of said passage and opening into said working space on the inlet side of said piston and a second bore coaxial with said outlet bore and extending transversely of said passage.

7. The structure of claim 6 wherein said adjustable means for varying the flow area is defined by an element positioned for movement axially of said passage and movable across said second bore to restrict flow therethrough, said valve including means for moving said element and stop means for limiting movement across said second bore to a position leaving a small flow space through said second bore.

8. The structure of claim 7 wherein said stop means is defined by a shoulder in said passage.

9. The structure of claim 7 wherein said means for moving said element is defined by a screw threaded in said body and carrying said element.