Load control and holding valve

Claim 2

A valve assembly comprising a body having motor, valve, and pilot ports, and a main passage connecting said valve and motor ports; a normally closed main valve controlling flow of fluid through said main passage having areas on one said thereof exposed to fluid pressure in said motor and valve ports respectively, said main valve and body defining a pressure chamber having restricted communication with said motor port and less restricted communication with said valve port via a control passage connecting said chamber and valve port; said main valve having an area on the other side thereof exposed to fluid pressure in said chamber; a normally closed pilot valve controlling flow of fluid through said control passage; and means operated by fluid pressure in said pilot port having a surface radially overlapped with said pilot valve for pulling open said pilot valve to thus decrease the fluid pressure in said chamber relative to the fluid pressure in said motor port whereby predominant fluid pressure in said motor port opens said main valve for flow of fluid through said main passage from said motor port to said valve port.

Claim 3

A valve assembly comprising a body having motor, valve, and pilot ports, and a main passage connecting said valve and motor ports; a normally closed main valve controlling flow of fluid through said main passage having areas on one side thereof exposed to fluid pressure in said motor and a valve ports respectively, said main valve and body defining a pressure chamber having restricted communication with said motor port and less restricted communication with said valve port via a control passage connecting said chamber and valve port; said main valve having an area on the oTher side thereof exposed to fluid pressure in said chamber; a normally closed pilot valve controlling flow of fluid through said control passage; and means operated by fluid pressure in said pilot port for opening said pilot valve to thus decrease the fluid pressure in said chamber relative to the fluid pressure in said motor port whereby predominant fluid pressure in said motor port opens said main valve for flow of fluid through said main passage from said motor port to said valve port; said pilot valve being spring biased to closed position and being operable to open position independently of said last-named means by a predetermined pressure in said chamber.

Claim 4

A valve assembly comprising a body having motor, valve, and pilot ports, and a main passage connecting said valve and motor ports; a normally closed main valve controlling flow of fluid through said main passage having areas on one side thereof exposed to fluid pressure in said motor and a valve ports respectively, said main valve and body defining a pressure chamber having restricted communication with said motor port and less restricted communication with said valve port via a control passage connecting said chamber and valve port; said main valve having an area on the oTher side thereof exposed to fluid pressure in said chamber; a normally closed pilot valve controlling flow of fluid through said control passage; and means operated by fluid pressure in said pilot port for opening said pilot valve to thus decrease the fluid pressure in said chamber relative to the fluid pressure in said motor port whereby predominant fluid pressure in said motor port opens said main valve for flow of fluid through said main passage from said motor port to said valve port; said pilot valve being spring biased to closed position and being operable to open position independently of said last-named means by a predetermined pressure in said chamber.

Claim 5

The valve assembly of claim 2 wherein decrease of said fluid pressure in said pilot port to a predetermined value permits spring biased closing of said pilot valve thus to effect closing of said main valve member to block flow of fluid through said main passage from said motor port to said valve port.

Claim 6

A valve assembly comprising a body having motor, valve, and pilot ports, and a main passage connecting said valve and motor ports; a normally closed main valve controlling flow of fluid through said main passage having areas on one side thereof exposed to fluid pressure in said motor and valve ports respectively, said main valve and body defining a pressure chamber having restricted communication with said motor port and less restricted communication with said valve port via a control passage connecting said chamber and valve port; said main valve having an area on the other side thereof exposed to fluid pressure in said chamber; a normally closed pilot valve controlling flow of fluid through said control passage; and means operated by fluid pressure in said pilot port for opening said pilot valve to thus decrease the fluid pressure in said chamber relative to the fluid pressure in said motor port whereby predominant fluid pressure in said motor port opens said main valve for flow of fluid through said main passage from said motor port to said valve port; said pilot valve constituting a pilot relief valve which opens said control passage independently of said fluid pressure operated means to open said main valve to relieve excess fluid pressure in said motor port to said valve port.

Claim 7

A valve assembly comprising a body having motor, valve, and pilot ports, and a main passage connecting said valve and motor ports; a normally closed main valve controlling flow of fluid through said main passage having areas on one side thereof exposed to fluid pressure in said motor and valve ports respectively, said main valve and body defining a pressure chamber having restricted communication with said motor port and less restricted communication with said valve port via a control passage connecting said chamber and valve port; said main valve having an area on the other side thereof exposed to fluid pressure in said chamber; a normally closed pilot valve controlling flow of fluid through said control passage; and means operated by fluid pressure in said pilot port for opening said pilot valve to thus decrease the fluid pressure in said chamber relative to the fluid pressure in said motor port whereby predominant fluid pressure in said motor port opens said main valve for flow of fluid through said main passage from said motor port to said valve port; said pilot valve constituting a pilot relief valve which opens said control passage independently of said fluid pressure operated means to open said main valve to relieve excess fluid pressure in said motor port to said valve port.

Claim 8

A load control and holding valve comprising a housing having motor, valve, and pilot ports, a main passage having a main valve seat communicating said valve and motor ports with each other, and a control passage having a pilot valve seat communicating a chamber in said housing with said valve port; a main valve member movable in said housing into engagement with said main valve seat to close said main passage and out of engagement with said main valve seat to permit flow of fluid from said valve port to said motor port and vice versa, said main valve member defining with said housing said chamber which has restricted communication with said motor port; a pilot valve member movable in said housing into engagement with said pilot valve seat to close said control passage to equalize the fluid pressures in said chamber and said motor port through such restricted communication and out of engagement with said pilot valve seat to communicate said chamber with said valve port via said control passage thereby to decrease the fluid pressure in said chamber relative to fluid pressure in said motor port for opening of said main valve member by predominant pressure in said motor port for flow of fluid through said main passage from said motor port to said valve port; and fluid pressure operated means in said housing operative in response to fluid pressure in said pilot port to pull said pilot valve member out of engagement with said pilot valve seat.

Claim 9

A load control and holding valve comprising a housing having motor, valve, and pilot ports, a main passage having a main valve seat communicating said valve and motor ports with each other, and a control passage having a pilot valve seat communicating a chamber in said housing with said valve port; a main valve member movable in said housing into engagement with said main valve seat to close said main passage and out of engagement with said main valve seat to permit flow of fluid from said valve port to said motor port and vice versa, said main valve member defining with said housing said chamber which has restricted communication with said motor port; a pilot valve member movable in said housing into engagement with said pilot valve seat to close said control passage to equalize the fluid pressures in said chamber and said motor port through such restricted communication and out of engagement with said pilot valve seat to communicate said chamber with said valve port via said control passage thereby to decrease the fluid pressure in said chamber relative to fluid pressure in said motor port for opening of said main valve member by predominant pressure in said motor port for flow of fluid through said main passage from said motor port to said valve port; and fluid pressure operated means in said housing operative in response to fluid pressure in said pilot port to pull said pilot valve member out of engagement with said pilot valve seat.

Claim 10

A load control and holding valve comprising a housing having motor, valve, and pilot ports, a main passage having a main valve seat communicating said valve and motor ports with each other, and a control passage having a pilot valve seat communicating a chamber in said housing with saId valve port; a main valve member movable in said housing into engagement with said main valve seat to close said main passage and out of engagement with said main valve seat to permit flow of fluid from said valve port to said motor port and vice versa, said main valve member defining with said housing said chamber which has restricted communication with said motor port; a pilot valve member movable in said housing into engagement with said pilot valve seat to close said control passage to equalize the fluid pressures in said chamber and said motor port through such restricted communication and out of engagement with said pilot valve seat to communicate said chamber with said valve port via said control passage thereby to decrease the fluid pressure in said chamber relative to fluid pressure in said motor port for opening of said main valve member by predominant pressure in said motor port for flow of fluid through said main passage from said motor port to said valve port; and fluid pressure operated means in said housing operative in response to fluid pressure in said pilot port to move said pilot valve member out of engagement with said pilot valve seat; spring means biasing said pilot valve member into engagement with said pilot valve seat whereby equal fluid pressures in said motor port and chamber retains said main valve member in engagement with said main valve seat thus to hold a load on a fluid motor adapted to be connected to said motor port until fluid pressure in said pilot port acting on said fluid pressure operated means is sufficient to overcome such spring bias to move said pilot valve member out of engagement with said pilot valve seat; said pilot valve member being movable out of engagement with said pilot valve seat independently of said fluid pressure operated means when the fluid pressure in said motor port and chamber exceeds a predetermined maximum which overcomes said spring bias thus to effect movement of said pilot valve member out of engagement with said pilot valve seat and consequent movement of said main valve member out of engagement with said main valve seat to relieve excess fluid pressure in said motor port to said valve port via said main passage.

Claim 11

A load control and holding valve comprising a housing having motor, valve, and pilot ports, a main passage having a main valve seat communicating said valve and motor ports with each other, and a control passage having a pilot valve seat communicating a chamber in said housing with saId valve port; a main valve member movable in said housing into engagement with said main valve seat to close said main passage and out of engagement with said main valve seat to permit flow of fluid from said valve port to said motor port and vice versa, said main valve member defining with said housing said chamber which has restricted communication with said motor port; a pilot valve member movable in said housing into engagement with said pilot valve seat to close said control passage to equalize the fluid pressures in said chamber and said motor port through such restricted communication and out of engagement with said pilot valve seat to communicate said chamber with said valve port via said control passage thereby to decrease the fluid pressure in said chamber relative to fluid pressure in said motor port for opening of said main valve member by predominant pressure in said motor port for flow of fluid through said main passage from said motor port to said valve port; and fluid pressure operated means in said housing operative in response to fluid pressure in said pilot port to move said pilot valve member out of engagement with said pilot valve seat; spring means biasing said pilot valve member into engagement with said pilot valve seat whereby equal fluid pressures in said motor port and chamber retains said main valve member in engagement with said main valve seat thus to hold a load on a fluid motor adapted to be connected to said motor port until fluid pressure in said pilot port acting on said fluid pressure operated means is sufficient to overcome such spring bias to move said pilot valve member out of engagement with said pilot valve seat; said pilot valve member being movable out of engagement with said pilot valve seat independently of said fluid pressure operated means when the fluid pressure in said motor port and chamber exceeds a predetermined maximum which overcomes said spring bias thus to effect movement of said pilot valve member out of engagement with said pilot valve seat and consequent movement of said main valve member out of engagement with said main valve seat to relieve excess fluid pressure in said motor port to said valve port via said main passage.

Claim 12

In a load control and holding valve of the type wherein a valve housing has valve, motor, and pilot ports therein, and has valve means and fluid pressure operated valve actuating means therein which valve means opens communication between said valve and motor ports responsive to predominant fluid pressure in said valve port for flow of fluid to said motor port and which opens communication between said valve and motor ports responsive to predetermined fluid pressure in said pilot port which acts on said valve actuating means for flow of fluid to said valve port, the improvement which comprises valve means and actuating means therefor including a unitary valve member which defines with said housing a pressure seating chamber having restricted communication with said motor port; and a pilot valve member which is actuated by said actuating means to decrease the fluid pressure in said chamber relative to fluid pressure in said motor port whereby predominant motor port fluid pressure in relation to chamber pressure and valve port pressure moves said unitary valve member to open communication between said motor and valve ports for flow of fluid from said motor port to said valve port, said unitary valve member further being operative to open communication between said valve and motor ports for flow of fluid from said valve port to said motor port when the fluid pressure in said valve port exceeds that in said motor port and said chamber when the pressure in said pilot port is less than such predetermined value; said housing having a control passage between said chamber and said valve port which is opened or closed by said pilot valve member according to whether fluid pressure in said pilot port is equal to or less than such predetermined value; said pilot valve member being spring biased to a position cLosing said control passage; and said pilot valve member being operative independently of said actuating means to open said control passage responsive to fluid pressure in said motor port and chamber exceeding a predetermined maximum value overcoming such spring bias thus to relieve excess pressure for flow from said motor port to said valve port by consequent movement of said main valve member to open communication between said motor and valve ports.

Claim 13

In a load control and holding valve of the type wherein a valve housing has valve, motor, and pilot ports therein, and has valve means and fluid pressure operated valve actuating means therein which valve means opens communication between said valve and motor ports responsive to predominant fluid pressure in said valve port for flow of fluid to said motor port and which opens communication between said valve and motor ports responsive to predetermined fluid pressure in said pilot port which acts on said valve actuating means for flow of fluid to said valve port, the improvement which comprises valve means and actuating means therefor including a unitary valve member which defines with said housing a pressure seating chamber having restricted communication with said motor port; and a pilot valve member which is actuated by said actuating means to decrease the fluid pressure in said chamber relative to fluid pressure in said motor port whereby predominant motor port fluid pressure in relation to chamber pressure and valve port pressure moves said unitary valve member to open communication between said motor and valve ports for flow of fluid from said motor port to said valve port, said unitary valve member further being operative to open communication between said valve and motor ports for flow of fluid from said valve port to said motor port when the fluid pressure in said valve port exceeds that in said motor port and said chamber when the pressure in said pilot port is less than such predetermined value; said housing having a control passage between said chamber and said valve port which is opened or closed by said pilot valve member according to whether fluid pressure in said pilot port is equal to or less than such predetermined value; said pilot valve member being spring biased to a position cLosing said control passage; and said pilot valve member being operative independently of said actuating means to open said control passage responsive to fluid pressure in said motor port and chamber exceeding a predetermined maximum value overcoming such spring bias thus to relieve excess pressure for flow from said motor port to said valve port by consequent movement of said main valve member to open communication between said motor and valve ports.

Claim 14

A load control and holding valve comprising a housing having a first passage with a main valve seat; a pilot operated relief valve in said housing comprising a spring biased main valve member movable into and out of engagement with said main valve seat and defining with said housing the movable wall of a chamber having one side thereof in restricted communication with the other side thereof; said housing having a second passage communicating said chamber with said first passage on one side of said main valve seat and having a pilot valve seat therein; a spring biased pilot valve member movable into and out of engagement said said pilot valve seat to open and close said second passage whereby when fluid under pressure on said other side of said main valve member and in said chamber attains a magnitude sufficient to move said pilot valve member out of engagement with said pilot valve seat said chamber is vented through said second passage more rapidly than fluid can be replenished into said chamber from the other side of said main valve member whereby said main valve member is moved out of engagement with said main valve seat to relieve such pressure in said first passage on the other side of said main valve seat for flow in one direction through said first passage; said main valve member being moved as a check valve member when the pressure of said one side of said main valve seat in said first passage exceeds the pressure on the other side of said main valve seat thus to permit flow of fluid through said first passage in the opposite direction; said housing having a pilot pressure passage; a piston movable in said housing to engage said pilot valve member to move it out of engagement with said pilot valve seat when the pilot pressure in said pilot passage acting on said piston rises to a value sufficient to overcome the spring bias on said pilot valve member thus to again permit movement of said main valve member out of engagement with its seat for flow of fluid in such one direction through said first passage.

Claim 15

A load control and holding valve comprising a housing having a first passage with a main valve seat; a pilot operated relief valve in said housing comprising a spring biased main valve member movable into and out of engagement with said main valve seat and defining with said housing the movable wall of a chamber having one side thereof in restricted communication with the other side thereof; said housing having a second passage communicating said chamber with said first passage on one side of said main valve seat and having a pilot valve seat therein; a spring biased pilot valve member movable into and out of engagement said said pilot valve seat to open and close said second passage whereby when fluid under pressure on said other side of said main valve member and in said chamber attains a magnitude sufficient to move said pilot valve member out of engagement with said pilot valve seat said chamber is vented through said second passage more rapidly than fluid can be replenished into said chamber from the other side of said main valve member whereby said main valve member is moved out of engagement with said main valve seat to relieve such pressure in said first passage on the other side of said main valve seat for flow in one direction through said first passage; said main valve member being moved as a check valve member when the pressure of said one side of said main valve seat in said first passage exceeds the pressure on the other side of said main valve seat thus to permit flow of fluid through said first passage in the opposite direction; said housing having a pilot pressure passage; a piston movable in said housing to engage said pilot valve member to move it out of engagement with said pilot valve seat when the pilot pressure in said pilot passage acting on said piston rises to a value sufficient to overcome the spring bias on said pilot valve member thus to again permit movement of said main valve member out of engagement with its seat for flow of fluid in such one direction through said first passage.

Claim 16

The valve of claim 8 wherein said piston and pilot valve member have radially overlapped surfaces which engage each other when said piston is moved responsive to such pilot pressure in said pilot passage.

Claim 17

The valve of claim 8 wherein decrease of such pilot pressure to a predetermined value permits spring biased movement of said pilot valve member into engagement with said pilot valve seat thus to effect movement of said main valve member into engagement with its seat to stop flow of fluid in said first passage in said one direction.

Claim 18

The valve of claim 8 wherein said first passage opens in a valve port adapted for connection with a four-way directional control valve and in a motor port adapted for connection with one motor port of a double acting fluid motor for flow of fluid into and from such motor via said first passage and said main valve seat; and wherein said pilot pressure passage is communicated with the other motor port which is connected to such directional control valve whereby when such other motor port of said motor is pressurized by operation of the directional control valve, pressure in said pilot pressure passage actuates said piston to open said pilot relief valve member as aforesaid.

Claim 19

The valve of claim 8 wherein said housing has a stepped bore in which said pilot operated relief valve is disposed with the first passage intersecting the smallest and second smallest bore portions of said bore, with said second passage intersecting the third smallest portion of said bore, anD with said pilot passage intersecting the fourth smallest portion of said bore, said main valve seat being disposed between said smallest and second smallest bore portions, said main valve member being movable in sliding contact with the second smallest bore portion, and said pilot operated relief valve comprising a tubular body secured in said housing with a first portion extending into said second smallest bore portion and sealed thereto, with a second portion sealingly engaged with the third smallest bore portion and a third portion having screw threaded engagement with the fourth smallest bore portion, said second passage intersecting the third smallest bore portion downstream of the pilot valve seat in said body, said pilot passage intersecting said fourth smallest bore portion and acting on an annular area of said piston reciprocable in said body, said body having an axially adjustable member therein telescoped within said piston to adjust the spring biasing force against said pilot valve member, said adjustment member having a passage therethrough and said piston having a passage to communicate a chamber on the other side of said piston with said second passage to permit piston movement without trapping of fluid on such other side.