Fluid controlling

Claim 2

A fluid control circuit comprising: a controller including a control element movable between first and second positions and operative for generating a fluid output signal dependent on the position of said element; a first pressure sensor connected to said controller and comprising a first valve body having a first pressure relief valve disposed therein for controlling flow from an inlet thereof to an outlet thereof; and, a second pressure sensor connected to said controller and comprising a second valve body having a second pressure relief valve disposed therein for controlling fluid from an inlet thereof to an outlet thereof, each of said inlets being adapted for connection to a source of pilot fluid to sense the pressure thereof, said controller including a third valve body having said control element disposed therein, a first control inlet connected to said outlet of said first valve body, a second control inlet connected to said outlet of said second valve body, and an outlet, said first sensor being operable for causing said control element to assume its second position when the sensed pilot fluid pressure exceeds a predetermined upper level, and said second sensor being operable for causing said control element to assume its first position when said sensed pilot fluid pressure is less than a predetermined lower level.

Claim 3

The fluid control circuit of claim 1 wherein at least one of said sensors is adjustable for varying the respective one of said first and second predetermined levels.

Claim 4

The fluid control circuit of claim 1 wherein said control element prevents flow through said third valve body from said one inlet to said outlet thereof in said first position thereof, permits said flow from said one inlet to said outlet in said second position thereof, and permits flow through said third valve body from said another inlet to said outlet in both said first and second position thereof.

Claim 5

The fluid control circuit of claim 3 wherein said controller is arranged such that when said control element is in said first position thereof flow of fluid from said second sensor to said controller is ineffective to cause movement of said control element to said second position thereof.

Claim 6

The fluid control circuit of claim 4 wherein said controller is arranged such that flow of fluid from said first sensor to said controller is effective to cause said control element to assume said second position thereof.

Claim 7

The fluid control circuit of claim 4 wherein said controller is arranged such that when said control element is in said second position thereof flow of fluid from said second sensor to said controller is effective to maintain said control element in said second position thereof.

Claim 8

The fluid control circuit of claim 3 wherein said control element is biased towards said first position thereof.

Claim 9

The fluid control circuit of claim 3 including a fourth valve body having a control inlet connected to said third valve body outlet, a main flow inlet, an outlet, and a bypass valve disposed therein for controlling flow therethrough between said main flow inlet and said outlet and responsive to flow from said control inlet.

Claim 10

The fluid control circuit of claim 3 wherein said bypass valve comprises a poppet spool movable between a closed position preventing said flow therethrough and an open position permitting said flow therethrough and is biased towards said closed position, one end of said spool defining a control surface arranged such that fluid from said controller applied to said control surface tends to move said spool into its open position.

Claim 11

The fluid control circuit of claim 1 including a plurality of interconnected valving modules; a first one of said modules comprising said first sensor; a second one of said modules comprising said second sensor; a third one of said modules comprising said controller, and being arranged such that said control element prevents flow from said second control inlet to said outlet in said first position thereof, permits said flow from said second control inlet to said outlet in said second position thereof, and permits flow from said first control inlet to said outlet in said first and second positions thereof; and, a fourth one of said modules including a control inlet connected to said outlet of said third one module, a main flow inlet and a main flow outlet, and having a bypass flow element disposed therein arranged for controlling flow between said main flow inlet and said main flow outlet, said controller being further arranged such that flow from said second sensor to said controller when said control element is in said first position is ineffective to cause movement of said control element to said second position thereof, said flow from said second sensor when said control element is in said second position thereof is effective to maintain said control element in said second position thereof, and flow from said first sensor to said controller is effective to cause said control element to assume said second position thereof, and said bypass flow element comprising a poppet spool movable between a closed position preventing flow from said main inlet to said main flow outlet and an open position permitting said flow from said main inlet to said main outlet, said spool being biased towards its closed position and one end of said spool defining a control surface arranged such that fluid from said controller to said control inlet applied to said control surface tends to move said spool into its open position.

Claim 12

The fluid control circuit of claim 10 wherein a fifth one of said modules includes a main flow inlet conduit having an inlet adapted to be connected to a source of fluid, an outlet adapted to be connected to a load, a check valve disposed therein and biased towards its closed pposition for controlling flow therethrough, a first bypass flow conduit connecting the upstream side of said check valve in said main flow conduit to said main flow inlet of said fourth one module, a second bypass flow conduit extending from a bypass flow outlet of said fifth one module to said main flow outlet of said fourth one module, and a pilot pressure conduit extending from the downstream side of said check valve in said main flow conduit to a pilot outlet, and wherein said circuitry further includes means connecting the inlets of each of said first one and second one modules to saId pilot outlet of said fifth one module.

Claim 13

A fluid control circuit comprising: a controller including a control element movable between first and second positions and operative for generating a fluid output signal dependent on the position of said element; a first pressure sensor connected to said controller and adapted for connection to a source of pilot fluid to sense the pressure thereof; and, a second pressure sensor connected to said controller and adapted for connection to said source to sense the pressure of said pilot fluid, said first sensor being operable for causing said control element to assume its second position when the sensed pilot fluid pressure exceeds a predetermined upper level, and for passing fluid from said pilot source to said controller along a first path when said sensed fluid pressure exceeds said upper level and for preventing flow along said first path when said sensed fluid pressure is less than said upper level, and said second sensor being operable for causing said control element to assume its first position when said sensed pilot fluid pressure is less than a predetermined lower level, and for passing flow from said source to said controller along a second path when said sensed fluid pressure exceeds said lower level and for preventing flow along said second path when said sensed fluid pressure is less than said lower level.

Claim 14

A fluid control circuit comprising: a controller including a control element movable between first and second positions and operative for generating a fluid output signal dependent on the position of said element; a first pressure sensor connected to said controller and adapted for connection to a source of pilot fluid to sense the pressure thereof; and, a second pressure sensor connected to said controller and adapted for connection to said source to sense the pressure of said pilot fluid, said first sensor being operable for causing said control element to assume its second position when the sensed pilot fluid pressure exceeds a predetermined upper level, and for passing fluid from said pilot source to said controller along a first path when said sensed fluid pressure exceeds said upper level and for preventing flow along said first path when said sensed fluid pressure is less than said upper level, and said second sensor being operable for causing said control element to assume its first position when said sensed pilot fluid pressure is less than a predetermined lower level, and for passing flow from said source to said controller along a second path when said sensed fluid pressure exceeds said lower level and for preventing flow along said second path when said sensed fluid pressure is less than said lower level.

Claim 15

The fluid control circuit of claim 12 wherein when said control element is in said first position said controller and sensors are operative to cause said control element to remain in said first position when said sensed pressure is intermediate said upper and lower levels.

Claim 16

The fluid control circuit of claim 12 wherein when said control element is in said second position said controller and sensors are operative to cause said control element to remain in said second position when said sensed pressure is intermediate said upper and lower levels.

Claim 17

The fluid control circuit of claim 12 wherein said control element is biased towards said first position thereof and is operative to prevent flow of fluid through said controller from said second sensor in said first position thereof.

Claim 18

The fluid control circuit of claim 12 including a valve body having a bypass flow valve disposed therein, a control inlet connected to said controller, a main inlet for connection to a fluid source, and an outlet, said bypass flow valve being movable between a closed position preventing flow from said main inlet through said valve body to said outlet and an open position permitting said flow through said valve body, and said controller being operative to move said bypass flow valve into the open position thereof in response to movement of said control element into said second position thereof.

Claim 19

The fluid control circuit of claim 16 wherein said bypass flow valve is biased towards said closed position thereof.

Claim 20

The fluid control circuit of claim 16 wherein each of said sensors is adjustable for varying the respective one of said upper and lower predetermined levels.