Pilot valve

Claim 2

A pilot valve comprising, a body having three ports in communication with a bore through said body and three valve seats defined within the bore of said body, the first of said ports communicating with said bore on the first side of the first of said valve seats, the second of said ports communicating with said bore between the second and third of said valve seats, the third of said ports communicating with said bore on the opposite side of said third valve seat from said second port, a first valve member movably mounted within said bore and adapted to engage said first and second valve seats, said first valve member engaging only one of said valve seats at a time, a second valve member movably mounted to engage the third valve seat, means urging said second valve member toward engagement with said third valve seat, and a rod extending between said first valve member and said second valve member, said rod being sufficiently long so that when said first valve member is seated on said second valve seat, said second valve member is held out of engagement with said third valve seat and when said second valve member is seated, said first valve member is held out of engagement with said second valve seat.

Claim 3

A pilot valve according to claim 1, including means for adjusting the relative position of said second valve seat within said bore with respect to said third valve seat.

Claim 4

A pilot valve according to claim 1, including stop means coacting with said position adjusting means to prevent moving said valve seats sufficiently far apart with respect to said rod to allow both of said second and said third valve seats to be closed at one time.

Claim 5

A pilot valve according to claim 1, including a valve body having an axial bore, a tubular retainer positioned in said axial bore and having an outwardly extending annular flange, and a sealing ring mounted around said tubular retainer between said flange and said valve body whereby said retainer equalizes pressures across said sealing ring, said sealing ring adapted to engage said second valve seat.

Claim 6

A pilot valve according to claim 1, including a second sealing ring mounted on the opposite end of said body from said first sealing ring, said second sealing ring adapted to engage said first valve seat.

Claim 7

A pilot valve according to claim 1, including said second valve member includes a radially extending flange, said flange coacts with said body to restrict the flow of fluid to said third port after said second valve member initially disengages from said third valve seat to exert additional pressure force on said second valve member to snap it to full open position.

Claim 8

A pilot valve according to claim 1, including a fluid pressure source, and means connecting said fluid pressure source to said pilot valve between said first and third valve seats whereby the opening setting of said second valve member may be tested.

Claim 9

A pilot valve according to claim 1, including said first valve member is free to move to and from seated engagement with said first valve seat responsive to pressure differentials exerted thereacross when said second valve member is in seated engagement with said third valve seat.

Claim 10

A pilot valve comprising, a body with a bore therein, means defining a first valve member chamber, a control chamber, and a second valve member chamber within said bore, an inlet port, said inlet port being in communication with said first valve member chamber through a first valve seat, said first valve member chamber in turn being in communication with said control chamber through a second valve seat, and said control chamber in turn being in communication with said second valve member chamber through a third valve seat, a control port in communication with said control chamber, and an outlet port in communication with said second valve member chamber, a first valve member movably mounted in said first valve member chamber and adapted to engage said first and second valve seats to control flow from said inlet port through said first valve member chamber to said control chamber, said first valve member engaging only one of said first and second valve seats at a time, a second valve member movably mounted in said second valve member chamber and adapted to engage said third valve seat to control flow from said control chamber to said outlet chamber, a rod extending between said first valve member and said second valve member, said rod being sufficiently long so that when said first valve member is seated on said second valve seat, said second valve member is held out of engagement with said third valve seat and when said second valve member is seated on said third valve seat, said first valve member is held out of engagement with said second valve seat, and means urging said second valve member toward engagement with said third valve seat, said first valve member opening in response to the pressure of the fluid in said inlet port, said second valve member opening in response to pressure from fluid flowing from said inlet port through said first valve member chamber to said control chamber, said first valve member seating on said second valve seat in response to flow from said inlet port through said control chamber to said second valve member chamber upon opening of said second valve member and thereby shutting off flow from said inlet port to said control chamber, said second valve member seating on said third valve seat and said first valve member moving out of engagement with said second valve seat when the force of said urging means overcomes the pressure of the fluid in the first valve member chamber.

Claim 11

A pilot valve comprising, a body with a bore therein, means defining a first valve member chamber, a control chamber, and a second valve member chamber within said bore, an inlet port, said inlet port being in communication with said first valve member chamber through a first valve seat, said first valve member chamber in turn being in communication with said control chamber through a second valve seat, and said control chamber in turn being in communication with said second valve member chamber through a third valve seat, a control port in communication with said control chamber, and an outlet port in communication with said second valve member chamber, a first valve member movably mounted in said first valve member chamber and adapted to engage said first and second valve seats to control flow from said inlet port through said first valve member chamber to said control chamber, said first valve member engaging only one of said first and second valve seats at a time, a second valve member movably mounted in said second valve member chamber and adapted to engage said third valve seat to control flow from said control chamber to said outlet chamber, a rod extending between said first valve member and said second valve member, said rod being sufficiently long so that when said first valve member is seated on said second valve seat, said second valve member is held out of engagement with said third valve seat and when said second valve member is seated on said third valve seat, said first valve member is held out of engagement with said second valve seat, and means urging said second valve member toward engagement with said third valve seat, said first valve member opening in response to the pressure of the fluid in said inlet port, said second valve member opening in response to pressure from fluid flowing from said inlet port through said first valve member chamber to said control chamber, said first valve member seating on said second valve seat in response to flow from said inlet port through said control chamber to said second valve member chamber upon opening of said second valve member and thereby shutting off flow from said inlet port to said control chamber, said second valve member seating on said third valve seat and said first valve member moving out of engagement with said second valve seat when the force of said urging means overcomes the pressure of the fluid in the first valve member chamber.