Rate of pressure rise limiting valve

Claim 2

For use in a hydraulic system, a multiple stage valve comprising a second stage valve section and a first stage pilot section operable to control opening of said second stage valve section, said pilot section being responsive only to inlet pressure rates of change and operable upon detection of excessive increases in pressure rates of change to spill hydraulic fluid to a low pressure zone and thereby open said second stage valve section.

Claim 3

The multiple stage valve of claim 1 wherein said first stage pilot section includes means to adjust the rate of pressure change to which said pilot section is responsive.

Claim 4

The multiple stage valve of claim 1 which further includes a third stage pilot section operable to control opening of said second stage valve section, said third stage pilot section being responsive to preset maximum pressures only and operable upon detection of said preset maximum pressures to spill hydraulic fluid to a low pressure zone and thereby open said second stage valve section.

Claim 5

For use in a hydraulic system, a multiple stage valve comprising a second stage valve section, and a static pressure insensitive, first stage pilot section operable to control opening of said second stage valve section, said pilot section being responsive to pressure rates of change and operable in response to detection of excessive increases in pressure rates of change to open said second stage valve section, said pilot valve section being operable to detect and respond to pressure rate of changes irrespective of the initial pressure at which such changes are initiated if the rate of such changes exceeds a predetermined value.

Claim 6

For use in a hydraulic system, a multiple stage valve comprising a second stage valve section, and a static pressure insensitive, first stage pilot section operable to control opening of said second stage valve section, said pilot section being responsive to pressure rates of change and operable in response to detection of excessive increases in pressure rates of change to open said second stage valve section, said pilot valve section being operable to detect and respond to pressure rate of changes irrespective of the initial pressure at which such changes are initiated if the rate of such changes exceeds a predetermined value.

Claim 7

The multiple stage valve of claim 4 wherein said first stage pilot section includes means to adjust the rate of pressure change to which said pilot section is responsive.

Claim 8

The multiple stage valve of claim 4 which further includes a third stage pilot section operable to control opening of said second stage valve Section, said third stage pilot section being responsive to direct pressure and operable upon detection of excessive pressures to open said second stage valve section.

Claim 9

For use in a hydraulic system, a multiple stage valve comprising a pilot operated valve section, and a pilot valve first stage section operable to control opening of said pilot operated valve section, said pilot valve first stage section being responsive to pressure rates of change to open said pilot operated valve section, said pilot valve first stage section including means to adjust the rate of pressure change to which said pilot valve first stage section is responsive.

Claim 10

For use in a hydraulic system, a multiple stage valve comprising a pilot operated valve section, and a pilot valve first stage section operable to control opening of said pilot operated valve section, said pilot valve first stage section being responsive to pressure rates of change to open said pilot operated valve section, said pilot valve first stage section including means to adjust the rate of pressure change to which said pilot valve first stage section is responsive.

Claim 11

The multiple stage valve of claim 7 wherein said pilot valve first stage section is operable to detect and respond to pressure rates of changes irrespective of the initial pressure at which such changes are initiated whenever the rate of such changes exceeds a predetermined value.

Claim 12

A rate of pressure increase responsive pilot unit for use with a relief valve of the type having an inlet port, an exhaust port, a piston valve between said inlet port and said exhaust port, and a control chamber at the opposite end of the piston from said inlet, said pilot unit comprising a body with a chamber communicating at spaced points with said control chamber and with said exhaust and having substantially unrestricted communication with said exhaust, a valve seat in said chamber between the points of communication thereof with said control chamber and exhaust, valve means resiliently urged by a spring means toward said valve seat from the side thereof communicating with said control chamber, restricted passageway means connecting both sides of said valve means to the pressure of said control chamber, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same chamber on the side of the valve means located adjacent the valve seat so that the net differential force acting against said valve means cooperates with said spring means to bias said valve means to a normally closed position, said restricted passageway means being of such a size that it restricts the passage of fluid therethrough so that fast rates of pressure increase in said control chamber cause said valve to open and spill control chamber fluid to exhaust through said open valve seat.

Claim 13

A rate of pressure increase responsive pilot unit for use with a relief valve of the type having an inlet port, an exhaust port, a piston valve between said inlet port and said exhaust port, and a control chamber at the opposite end of the piston from said inlet, said pilot unit comprising a body with a chamber communicating at spaced points with said control chamber and with said exhaust and having substantially unrestricted communication with said exhaust, a valve seat in said chamber between the points of communication thereof with said control chamber and exhaust, valve means resiliently urged by a spring means toward said valve seat from the side thereof communicating with said control chamber, restricted passageway means connecting both sides of said valve means to the pressure of said control chamber, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same chamber on the side of the valve means located adjacent the valve seat so that the net differential force acting against said valve means cooperates with said spring means to bias said valve means to a normally closed position, said restricted passageway means being of such a size that it restricts the passage of fluid therethrough so that fast rates of pressure increase in said control chamber cause said valve to open and spill control chamber fluid to exhaust through said open valve seat.

Claim 14

The pilot unit of claim 9 wherein said valve is generally cone shaped and said valve seat is generally circular in cross section.

Claim 15

The pilot unit of claim 9 wherein said pilot unit includes means to adjust the rate of pressure change to which said pilot unit responds.

Claim 16

In combination, a valve and a rate of pressure increase responsive pilot unit, said relief valve having an inlet port, an exhaust port, a piston valve between said inlet port and said exhaust port, and a control chamber at the opposite end of the piston from said inlet, said pilot unit comprising a body with a chamber communicating at spaced points with said control chamber and with said exhaust and having substantially unrestricted communication with said exhaust, a valve seat in said chamber between the points of communication thereof with said control chamber and exhaust, valve means resiliently urged by a spring means toward said valve seat from the side thereof communicating with said control chamber, restricted passageway means connecting both sides of said valve means to the pressure of said control chamber, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same chamber on the side of the valve means located adjacent the valve seat so that the net differential force acting against said valve means cooperates with said spring means to bias said valve means to a normally closed position, said restricted passageway means being of such a size That it restricts the passage of fluid therethrough so that fast rates of pressure increases in said control chamber cause said valve to open and spill control chamber fluid to exhaust through said open valve seat.

Claim 17

In combination, a valve and a rate of pressure increase responsive pilot unit, said relief valve having an inlet port, an exhaust port, a piston valve between said inlet port and said exhaust port, and a control chamber at the opposite end of the piston from said inlet, said pilot unit comprising a body with a chamber communicating at spaced points with said control chamber and with said exhaust and having substantially unrestricted communication with said exhaust, a valve seat in said chamber between the points of communication thereof with said control chamber and exhaust, valve means resiliently urged by a spring means toward said valve seat from the side thereof communicating with said control chamber, restricted passageway means connecting both sides of said valve means to the pressure of said control chamber, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same chamber on the side of the valve means located adjacent the valve seat so that the net differential force acting against said valve means cooperates with said spring means to bias said valve means to a normally closed position, said restricted passageway means being of such a size That it restricts the passage of fluid therethrough so that fast rates of pressure increases in said control chamber cause said valve to open and spill control chamber fluid to exhaust through said open valve seat.

Claim 18

The pilot unit of claim 12 wherein said pilot unit includes means to adjust the rate of pressure change to which said pilot unit responds.

Claim 19

The combination of claim 12 which further includes a pressure responsive pilot unit for said relief valve, said pressure responsive pilot unit comprising: a second body with a second chamber communicating at spaced points with said inlet and said control chamber and having substantially unrestricted communication with said exhaust, a second valve seat in said second chamber between the points of communication thereof with said control chamber and exhaust, and second valve means resiliently urged toward said second valve seat, said second valve means being operable to open and spill fluid from said control chamber to exhaust upon detection of pressure in said inlet port exceeding a predetermined value, spillage of fluid from said control chamber being operable to move said piston valve of said relief valve to an open condition and thereby connect said inlet port of said relief valve to said exhaust port.

Claim 20

The combination of claim 12 which further includes a pressure responsive pilot unit for the relief valve, said pressure responsive pilot unit comprising a second body with a second chamber communicating at spaced points with said inlet and said control chamber and having substantially unrestricted communication with said exhaust, a second valve seat in said second chamber between the points of communication thereof with said control chamber and exhaust, a second valve means resiliently urged toward said second valve seat from the side thereof communicating with exhaust, said second valve means presenting a uniform area to action of fluid pressure when in both open and closed condition, piston means disposed for movement in said second chamber between the points of communication thereof with said control chamber and said inlet, and passage means continually establishing restricted communication between the sections of said second chamber at the ends of said piston means.

Claim 21

A rate of pressure increase responsive pilot unit for use with a relief valve of the type having an inlet port, an exhaust port, a piston valve between said inlet port and said exhaust port, and a control chamber at the opposite end of the piston from said inlet, said pilot unit comprising: a body with a chamber communicating at spaced points with said control chamber and with said exhaust and having substantially unrestricted communication with said exhaust, a valve seat in said chamber between the points of communication thereof with said control chamber and exhaust, valve means resiliently urged by a spring toward said valve seat, said valve means including a piston movably mounted within said chamber, restricted passageway means through said valve means piston connecting both sides of said valve means piston to the pressure of said control chamber, the end of body chamber located on the side of said piston which is spaced away from said valve seat being closed except for said restricted passageway through said valve means piston, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same pressure on the side of the valve means located adjacent the valve seat so that the net differential pressure acting against said valve means cooperates with said spring to bias said valve means to a normally closed position, said restricted passageway means in said valve being of such a size that it restricts the passage of fluid therethrough so that fast rates of pressure increases in said control chamber cause said valve to open and spill control chamber fluid to exhaust through said open vaLve seat.

Claim 22

A rate of pressure increase responsive pilot unit for use with a relief valve of the type having an inlet port, an exhaust port, a piston valve between said inlet port and said exhaust port, and a control chamber at the opposite end of the piston from said inlet, said pilot unit comprising: a body with a chamber communicating at spaced points with said control chamber and with said exhaust and having substantially unrestricted communication with said exhaust, a valve seat in said chamber between the points of communication thereof with said control chamber and exhaust, valve means resiliently urged by a spring toward said valve seat, said valve means including a piston movably mounted within said chamber, restricted passageway means through said valve means piston connecting both sides of said valve means piston to the pressure of said control chamber, the end of body chamber located on the side of said piston which is spaced away from said valve seat being closed except for said restricted passageway through said valve means piston, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same pressure on the side of the valve means located adjacent the valve seat so that the net differential pressure acting against said valve means cooperates with said spring to bias said valve means to a normally closed position, said restricted passageway means in said valve being of such a size that it restricts the passage of fluid therethrough so that fast rates of pressure increases in said control chamber cause said valve to open and spill control chamber fluid to exhaust through said open vaLve seat.

Claim 23

A rate of pressure increase responsive valve comprising a body with a chamber communicating at spaced points with an inlet and with an outlet, said inlet being connected to a source of control pressure, and said outlet having substantially unrestricted communication with an exhaust pressure, a valve seat in said chamber between the points of communication thereof with said inlet and said outlet, valve means resiliently urged by a spring toward said valve seat, said valve means including a piston movably mounted within said chamber, restricted passageway means through said valve means piston connecting both sides of said valve means piston to said control pressure, the end of body chamber located on the side of said piston which is spaced away from said valve seat being closed except for said restricted passageway through said valve means piston, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same pressure on the side of the valve means located adjacent the valve seat so that the net differential force acting against said valve means cooperates with said spring to bias said valve means to a normally closed position, said restricted passageway means in said valve means piston being of such a size that it restricts the passage of fluid therethrough so that fast rates of pressure increases in said control pressure cause said valve means to open and spill fluid to a low pressure zone through said valve seat.

Claim 24

A rate of pressure increase responsive valve comprising a body with a chamber communicating at spaced points with an inlet and with an outlet, said inlet being connected to a source of control pressure, and said outlet having substantially unrestricted communication with an exhaust pressure, a valve seat in said chamber between the points of communication thereof with said inlet and said outlet, valve means resiliently urged by a spring toward said valve seat, said valve means including a piston movably mounted within said chamber, restricted passageway means through said valve means piston connecting both sides of said valve means piston to said control pressure, the end of body chamber located on the side of said piston which is spaced away from said valve seat being closed except for said restricted passageway through said valve means piston, said valve means presenting a larger area to action of control chamber pressure on the side away from the valve seat than is presented to the action of the same pressure on the side of the valve means located adjacent the valve seat so that the net differential force acting against said valve means cooperates with said spring to bias said valve means to a normally closed position, said restricted passageway means in said valve means piston being of such a size that it restricts the passage of fluid therethrough so that fast rates of pressure increases in said control pressure cause said valve means to open and spill fluid to a low pressure zone through said valve seat.

Claim 25

The rate of pressure increase responsive valve of claim 17 which further includes means to adjust the rate of pressure change necessary to move said valve means.

Claim 26

The rate of pressure increase responsive valve of claim 18 wherein said means to adjust the rate of pressure change comprises a plug movable within said closed end body chamber to vary the size of said closed end body chamber.

Claim 27

The rate of pressure increase responsive valve of claim 18 wherein said valve means is generally cone-shaped and said valve seat is circular in cross section.

Claim 28

For use in a hydraulic system which includes a pump and a fluid motor, a multiple stage valve comprising a second stage valve section and a first stage pilot section operable to control opening of said second stage valve section, said pilot section being responsive only to inlet pressure rates of change and operable upon detection of excessive increases in pressure rates of change to spill hydraulic fluid to a low pressure zone and thereby open said second stage valve section, and thereby reduce the volume delivery from said pump to said fluid motor.

Claim 29

For use in a hydraulic system which includes a pump and a fluid motor, a multiple stage valve comprising a second stage valve section and a first stage pilot section operable to control opening of said second stage valve section, said pilot section being responsive only to inlet pressure rates of change and operable upon detection of excessive increases in pressure rates of change to spill hydraulic fluid to a low pressure zone and thereby open said second stage valve section, and thereby reduce the volume delivery from said pump to said fluid motor.

Claim 30

The multiple stage valve of claim 21 wherein said first stage pilot section includes means to adjust the rate of pressure change to which said pilot section is responsive.

Claim 31

The multiple stage valve of claim 21 which further includes a third stage pilot section operable to control opening of said second stage valve section, said third stage pilot section being responsive to preset maximum pressures only and operable upon detection of said preset maximum pressures to spill hydraulic fluid to a low pressure zone and thereby open said second stage valve section.