Spool valve assembly

Claim 2

A valve assembly comprising a housing having a bore intersected axially therealong by inlet, return, and motor passages adapted for connection with a fluid pressure source, a tank, and a fluid motor respectively; a valve member movable in said bore to selectively communicate said motor passage with said inlet passage or with said return passage; a check valve assembly in said motor passage opened by fluid pressure when said valve member is moved to communicate said inlet passage with said motor passage; said check valve assembly and said valve member having cooperating cam means operative to open said check valve assembly when said valve member is moved to communicate said motor passage with said return passage; and adjusting means adjustably securing said check valve assembly in said housing to effect predetermined degree of actuation of said check valve assembly by said cam means upon movement of said valve member to the last-mentioned position ;said check valve assembly comprising a body having a main check valve seat, a main check valve member movable in said body into and out of engagement with said seat and defining with said body a chamber having restricted communication with the portion of the motor passage which is on the outlet side of said main check valve member, said maiN check valve member having a pilot check valve seat, a pilot check valve member actuated by said cam means to a position out of engagement with said pilot check valve seat to vent said chamber to said tank passage via the portion of the motor passage on the inlet side of said main check valve member faster than fluid can be replenished into said chamber via said restricted communication whereby higher pressure acting on the outlet side of said main check valve member than on the inlet side thereof and in said chamber moves said main check valve member out of engagement with the main check valve seat.

Claim 3

The valve assembly of claim 1 wherein another check valve means in said body, in addition to said restricted communication, vents said chamber to the outlet side of said main check valve member for rapid opening of the latter when the inlet side of the motor passage is communicated with said inlet passage, said another check valve means preventing rapid buildup of pressure in said chamber in the event of pressure surges or pulsations in the portion of the motor passage on outlet side of said main check valve member whereby to decrease chatter or flutter of the latter.

Claim 4

The valve assembly of claim 1 wherein said cam means comprises a frusto-conical cam surface on said valve member, and a cam follower engaging said pilot check valve member and said cam surface to move said pilot check valve member out of engagement with said pilot check valve seat upon movement of said valve member to a position communicating said motor passage with said return passage.

Claim 5

The valve assembly of claim 3 wherein said adjusting means enables adjustment of said body in said housing so that said main check valve member may be engaged by said cam follower to move said main check valve member away from its seat upon movement of said valve member to a position communicating said motor passage with said return passage.

Claim 6

The valve assembly of claim 3 wherein said adjusting means enables adjustment of said body, and thus said pilot check valve member, in said housing so that said pilot check valve member is moved a predetermined distance away from its seat upon movement of said valve member to a position communicating said motor passage with said return passage.

Claim 7

A valve assembly comprising a housing having a bore intersected axially therealong by an inlet passage for connection with a fluid pressure source, a pair of motor passages straddling said inlet passage for connection with a double-acting fluid motor, and a pair of return passages straddling said motor passages; a valve spool in said bore movable from a neutral position blocking communication of said motor passages with said inlet and return passages to operating positions selectively communicating said motor passages with inlet and return passages to control the direction of actuation of such fluid motor; a pilot operated check valve assembly in each motor passage arranged to be opened by fluid pressure when its motor passage is communicated with said inlet passage to permit flow of fluid to such motor, and to be opened by cam means on said spool when its motor passage is communicated with the adjacent return passage; each check valve assembly comprising a body adjustably secured in said housing for adjustment toward or away from said spool and having a seat; a main check valve member movable in said body into and out of engagement with said seat to permit flow of fluid through said motor passage to or from the motor as aforesaid; said main check valve member having a pilot check valve member seat and defining with said body a chamber which has restricted communication with said motor passage downstream of said body seat; a pilot check valve member engaged with said pilot seat and movable into and out of engagement with said pilot seat to vent said chamber to the motor passage upstream of said body seat faster than fluid can be replenished into said chamber through such restricted communication whereby higher fluid pRessure downstream of said body seat moves said main check valve member away from said body seat for return flow of fluid from the motor through said motor passage when it is communicated with the adjacent return passage; each said cam means comprising a frustoconical cam surface on said spool; and a cam follower engaging said pilot check valve member and said cam surface to move said pilot check valve member out of engagement with said pilot seat upon movement of said spool to communicate said motor passage with the adjacent return passage; the adjustment of each body in said housing varying the distances between said body and pilot seats and said cam surface to insure desired opening of said pilot check valve member by said cam follower and to enable engagement of said cam follower with said main check valve member to move the latter out of engagement with said body seat after the pressure in said chamber has been decreased by opening of said pilot check valve member.

Claim 8

A valve assembly comprising a housing having a bore intersected axially therealong by an inlet passage for connection with a fluid pressure source, a pair of motor passages straddling said inlet passage for connection with a double-acting fluid motor, and a pair of return passages straddling said motor passages; a valve spool in said bore movable from a neutral position blocking communication of said motor passages with said inlet and return passages to operating positions selectively communicating said motor passages with inlet and return passages to control the direction of actuation of such fluid motor; a pilot operated check valve assembly in each motor passage arranged to be opened by fluid pressure when its motor passage is communicated with said inlet passage to permit flow of fluid to such motor, and to be opened by cam means on said spool when its motor passage is communicated with the adjacent return passage; each check valve assembly comprising a body adjustably secured in said housing for adjustment toward or away from said spool and having a seat; a main check valve member movable in said body into and out of engagement with said seat to permit flow of fluid through said motor passage to or from the motor as aforesaid; said main check valve member having a pilot check valve member seat and defining with said body a chamber which has restricted communication with said motor passage downstream of said body seat; a pilot check valve member engaged with said pilot seat and movable into and out of engagement with said pilot seat to vent said chamber to the motor passage upstream of said body seat faster than fluid can be replenished into said chamber through such restricted communication whereby higher fluid pRessure downstream of said body seat moves said main check valve member away from said body seat for return flow of fluid from the motor through said motor passage when it is communicated with the adjacent return passage; each said cam means comprising a frustoconical cam surface on said spool; and a cam follower engaging said pilot check valve member and said cam surface to move said pilot check valve member out of engagement with said pilot seat upon movement of said spool to communicate said motor passage with the adjacent return passage; the adjustment of each body in said housing varying the distances between said body and pilot seats and said cam surface to insure desired opening of said pilot check valve member by said cam follower and to enable engagement of said cam follower with said main check valve member to move the latter out of engagement with said body seat after the pressure in said chamber has been decreased by opening of said pilot check valve member.

Claim 9

The valve assembly of claim 6 wherein the ends of said spool and said housing define chambers having restricted communication with said inlet passage; and wherein solenoid operated valves are selectively operative to vent either chamber to the adjacent return passage whereby fluid pressure in the unvented chamber urges said spool from neutral position to an operating position.

Claim 10

The valve assembly of claim 6 wherein each body has an adjustable threaded connection with said housing; wherein each body has an axially serrated portion therearound; and wherein a screw actuated clamp mechanism engages said serrated portions to lock said bodies in their respective adjusted positions.