Variable flow rate spray gun with pressure relief

Claim 2

A spray gun including a gun barrel having a fluid chamber defined within the barrel and spaced valve seats in the chamber, one of said valve seats defining a nozzle supply seat and being formed and adapted to afford communication with a nozzle on the barrel, the other of said valve seats defining a fluid return seat and being formed and adapted to communicate with a fluid return line opening into said barrel, a fluid pressure supply line connected with said barrel and opening into said chamber, a movable valve operating member in said chamber and having spaced valve portions cooperable with said valve seats, said valve portions being spaced so that when one of said portions is seated against said one valve seat, the other portion is spaced from the other valve seat and so that when said other portion seats against said other valve seat, said first named portion is spaced from said first named valve seat, a second chamber defined within said barrel, said operating member being in the form of a rod extending within said second chamber, a piston on said rod within said second chamber, means communicating the pressure within said first named chamber to said second chamber so as to exert closing forces against the piston within said second chamber and nozzle closing forces on said rod, and actuating means connected with said valve operating member to move the member respectively so that said valve portions move toward and away from said valve seats.

Claim 3

The structure of claim 1 wherein the valve portion adapted to seat against the fluid return seat of the chamber is tapered and movable gradually within said seat to provide a metered opening through said seat until said valve portion moves fully against the said seat.

Claim 4

The structure of claim 1 characterized by and including spring means for biasing said rod toward the nozzle supply seat.

Claim 5

The structure of claim 1 characterized by and including guiding and supporting elements on said rod in said first named chamber and supported by the wall of said first named chamber.

Claim 6

The structure of claim 1 wherein said valve portion which is cooperable with said return valve seat has a tapered portion adapted to progressively move within said seat and eventually completely close said seat, said tapered portion being effective to gradually close the outlet area through said seat as said portion moves within said seat, and adjustable stop means are associated with said actuating means so as to adjustably limit the travel of said tapered portion within said seat and thus limit the flow of fluid through said return seat and vary the outlet pressure through said nozzle seat.

Claim 7

A spray gun including a gun barrel having a fluid chamber defined within the barrel and spaced valve seats in the chamber, one of saiD valve seats defining a nozzle supply seat and being formed and adapted to afford communication with a nozzle on the barrel, the other of said valve seats defining a fluid return seat and being formed and adapted to communicate with a fluid return line opening into said barrel, a fluid pressure supply line connected with said barrel and opening into said chamber, a movable valve operating member in said chamber and having spaced valve portions cooperable with said valve seats, said valve portions being spaced so that when one of said portions is seated against said one valve seat, the other portion is spaced from the other valve seat and so that when said other portion seats against said other valve seat, said first named portion is spaced from said first named valve seat, a second fluid chamber defined within said gun barrel, said operating member being in the form of a rod passing through said second chamber and having a piston fixed thereto and subject to the pressure forces developed within said second chamber, said rod being hollow and having a first pressure inlet located within said first chamber and a fluid pressure outlet located within said second chamber so that the pressure in said first chamber is communicated through the hollow portions of said actuating rod to said second chamber to exert nozzle closing forces on said actuating rod, and actuating means connected with said valve operating member to move the member respectively so that said valve portions move toward and away from said valve seats.

Claim 8

A spray gun including a gun barrel having a fluid chamber defined within the barrel and spaced valve seats in the chamber, one of saiD valve seats defining a nozzle supply seat and being formed and adapted to afford communication with a nozzle on the barrel, the other of said valve seats defining a fluid return seat and being formed and adapted to communicate with a fluid return line opening into said barrel, a fluid pressure supply line connected with said barrel and opening into said chamber, a movable valve operating member in said chamber and having spaced valve portions cooperable with said valve seats, said valve portions being spaced so that when one of said portions is seated against said one valve seat, the other portion is spaced from the other valve seat and so that when said other portion seats against said other valve seat, said first named portion is spaced from said first named valve seat, a second fluid chamber defined within said gun barrel, said operating member being in the form of a rod passing through said second chamber and having a piston fixed thereto and subject to the pressure forces developed within said second chamber, said rod being hollow and having a first pressure inlet located within said first chamber and a fluid pressure outlet located within said second chamber so that the pressure in said first chamber is communicated through the hollow portions of said actuating rod to said second chamber to exert nozzle closing forces on said actuating rod, and actuating means connected with said valve operating member to move the member respectively so that said valve portions move toward and away from said valve seats.

Claim 9

The structure of claim 6 characterized by and including spring means for biasing said rod toward the gun closing position.

Claim 10

A spray gun including means defining a manipulating handle and a barrel carried by said handle, an actuating rod reciprocably mounted for movement within said barrel, said barrel having a nozzle outlet at one end thereof, said barrel having a fluid chamber in one end thereof with spaced valve seats at opposite ends of said chamber, seat, of said seats nearest the nozzle outlet defining a nozzle outlet seat and the other seat defining a fluid return seat, a fluid pressure supply line communicating with said chamber between said valve seats, said actuating rod extending within said chamber and having a first valve closure element cooperable with said nozzle outlet seat and a second valve closure element cooperable with said fluid return seat, a fluid return line connected to said barrel and communicating with a passage within said barrel aligned with said fluid return seat, means on said handle for reciprocating said rod, said valve portions being spaced so that when said first element is seated against its nozzle seat, the second valve element is spaced from said return seat so as to allow fluid from said inlet to pass through said fluid return seat, and so that when said second valve element seats against said return seat, said first named valve element is spaced away from said nozzle outlet seat to allow supply of the full inlet pressure through said chamber and through said nozzle, a second chamber within said barrel and a piston carried by said actuating rod and positioned within said second chamber, and means for communicating said first chamber with said second chamber in a manner such that the pressure within said first chamber operates against said piston to provide forces on said operating rod in a direction tending to close said first valve element against its associated seat, the effective cross-sectional area of said piston being such that the pressure exerted thereaginst essentially balances the opposite pressure forces exerted on said rod when said first valve element is away from its seat.

Claim 11

A spray gun including means defining a manipulating handle and a barrel carried by said handle, an actuating rod reciprocably mounted for movement within said barrel, said barrel having a nozzle outlet at one end thereof, said barrel having a fluid chamber in one end thereof with spaced valve seats at opposite ends of said chamber, seat, of said seats nearest the nozzle outlet defining a nozzle outlet seat and the other seat defining a fluid return seat, a fluid pressure supply line communicating with said chamber between said valve seats, said actuating rod extending within said chamber and having a first valve closure element cooperable with said nozzle outlet seat and a second valve closure element cooperable with said fluid return seat, a fluid return line connected to said barrel and communicating with a passage within said barrel aligned with said fluid return seat, means on said handle for reciprocating said rod, said valve portions being spaced so that when said first element is seated against its nozzle seat, the second valve element is spaced from said return seat so as to allow fluid from said inlet to pass through said fluid return seat, and so that when said second valve element seats against said return seat, said first named valve element is spaced away from said nozzle outlet seat to allow supply of the full inlet pressure through said chamber and through said nozzle, a second chamber within said barrel and a piston carried by said actuating rod and positioned within said second chamber, and means for communicating said first chamber with said second chamber in a manner such that the pressure within said first chamber operates against said piston to provide forces on said operating rod in a direction tending to close said first valve element against its associated seat, the effective cross-sectional area of said piston being such that the pressure exerted thereaginst essentially balances the opposite pressure forces exerted on said rod when said first valve element is away from its seat.

Claim 12

A spray gun including a gun barrel having a fluid chamber defined within the barrel and spaced valve seats in the chamber, one of said valve seats defining a nozzle supply seat and being formed and adapted to afford communication with a nozzle on the barrel, the other of said valve seats defining a fluid return seat and being formed and adapted to communicate with a fluid return line opening into said barrel, a fluid pressure supply line connected with said barrel and opening into said chamber, a movable valve operating member in said chamber and having spaced valve portions cooperable with said valve seats, said valve portions being spaced so that when one of said portions is seated against said one valve seat, the other portion is spaced from the other valve seat and so that when said other portion seats against said other valve seat, said first named portion is spaced from said first named valve seat, the valve portion cooperable with said return valve seat having a tapered portion adapted to progressively move within said return seat and eventually completely close said seat, said tapered portion being effective to gradually close the outlet area through said return seat as said tapered portion moves within said seat, actuating means connected with said valve operating member to move the member respectively so that said valve portions move toward and away from said valve seats, and adjustable stop means associated with said actuating means so as to adjustably limit the travel of said tapered portion within said return seat and thus limit the flow of fluid through said return seat while establishing a maximum pressure in said chamber and through said nozzle seat.

Claim 13

A spray gun including a gun barrel having a fluid chamber defined within the barrel and spaced valve seats in the chamber, one of said valve seats defining a nozzle supply seat and being formed and adapted to afford communication with a nozzle on the barrel, the other of said valve seats defining a fluid return seat and being formed and adapted to communicate with a fluid return line opening into said barrel, a fluid pressure supply line connected with said barrel and opening into said chamber, a movable valve operating member in said chamber and having spaced valve portions cooperable with said valve seats, said valve portions being spaced so that when one of said portions is seated against said one valve seat, the other portion is spaced from the other valve seat and so that when said other portion seats against said other valve seat, said first named portion is spaced from said first named valve seat, the valve portion cooperable with said return valve seat having a tapered portion adapted to progressively move within said return seat and eventually completely close said seat, said tapered portion being effective to gradually close the outlet area through said return seat as said tapered portion moves within said seat, actuating means connected with said valve operating member to move the member respectively so that said valve portions move toward and away from said valve seats, and adjustable stop means associated with said actuating means so as to adjustably limit the travel of said tapered portion within said return seat and thus limit the flow of fluid through said return seat while establishing a maximum pressure in said chamber and through said nozzle seat.