Fluid pressure system

Claim 2

A controL system, including, a primary element positioned by a variable condition, a first flapper structure connected to the primary element and positioned by the primary element which is positioned by the variable condition, a first relay controlled by pressure in its nozzle cooperating with the first flapper structure to develop a first fluid pressure relay output, a means arranged to regulate the variable condition and to be controlled by the fluid pressure output of the first relay, a second relay mounted adjacent the first relay controlled by pressure in its nozzle cooperating with a flapper structure to develop a second fluid pressure output, a second flapper structure connected to the primary element and positioned by the primary element to cooperate with the nozzle of the second relay to develop the second fluid pressure output, a source of fluid pressure for both relays, and a means connected to the second fluid pressure output to communicate a predetermined value of the variable condition.

Claim 3

The control system of claim 1, wherein, the primary element is a float and the variable condition is liquid level.

Claim 4

The level control system of claim 1, in which, the two relays are mounted upon each other as a single unit connected to the common source of fluid pressure.

Claim 5

The level control system of claim 1, in which, the second flapper structure is connected to the primary element so as to develop values for the second control fluid pressure having relationships different from the relationships between the values for first control fluid pressure output and the positions of the primary element.

Claim 6

The level control system of claim 1, including, a switch means in the connection of the first relay and the source of fluid pressure which is adaptable for manual manipulation to convert the relay output from throttling to snap-acting.

Claim 7

A fluid pressure relay for use in the control system of claim 1 as the first relay, and including, a control fluid pressure chamber connected to the nozzle, a source of fluid pressure connected to the control chamber, a flexible element arranged as a wall of the control fluid pressure chamber, a first portion of a valve element connected to the flexible element, a fluid pressure output chamber valved by the first portion of the valve element to the side of the flexible element outside of the control fluid pressure chamber, a fluid pressure supply chamber connected to the source of fluid pressure of the control chamber and valved to the output chamber, a second portion of a valve element arranged to valve fluid pressure of the supply chamber to the output chamber, a passageway in the second portion of the valve element and controlled by the first portion of the valve element in exhausting fluid pressure from the output chamber, and a switch means for alternatively connecting exhaust to the passageway and the outside of the flexible element, whereby the output chamber fluid pressure is given a throttling mode relation to the fluid pressure of the control chamber when the switch means is in its first position and a snap-acting mode relation to the fluid pressure of the control chamber when the switch means is in its second position.

Claim 8

A fluid pressure relay for use in the control system of claim 1 as the second relay, and including, a control fluid pressure chamber connected to its nozzle, a connection from the source of fluid pressure for the control chamber of the first relay to the control fluid pressure chamber of this second relay, and a means connected to receive the output fluid pressure of the control chamber of this second relay to manifest a predetermined value of the output fluid pressure.