Hydraulic control valve

Claim 2

A hydraulic control valve, comprising a valve body having an elongated chamber, a main flow input port and a main flow output port which both communicate with said chamber; a valve spool having a hollow interior which communicates with said chamber at one axial end of said spool, and a circumferential wall provided with an opening which communicates with said hollow interior, said spool being axially slidable in said chamber between a normal position in which said opening is out of communication with both of said ports, and two operated positions in each of which said opening is in communication with a respective one of said ports; an external port formed in said valve body and communicating with said chamber adjacent said one axial end of said spool; a pilot flow passage in said valve body, bypassing Said chamber and having one open end communicating with the exterior of said valve body and another open end communicating with said external port; orifice means interposed in said pilot flow passage intermediate said one end and said other end thereof; and aperture means communicating with said chamber adjacent the other end of said valve spool, and with said pilot flow passage intermediate said orifice means and said one end, so that a pressure difference which develops in said pilot flow passage across said orifice means acts upon said ends of said valve spool.

Claim 3

A control valve as defined in claim 1, wherein said input and output ports are used as common input and output ports; and further comprising an additional valve spool, pilot flow passage, orifice means and external port similar to the previously mentioned ones and also disposed in said control valve, whereby a pair of control valve units are incorporated in said control valve.

Claim 4

A control valve as defined in claim 2, further comprising additional orifice means interposed between said input and output ports.

Claim 5

A control valve as defined in claim 3, wherein some or all of said orifice means may have their cross-sectional areas varied by operation from the exterior of said control valve.

Claim 6

A control valve comprising a valve body; an internal passage in said valve body and having opposite end portions; an external input port and an external output port formed in said valve body and each communicating with said internal passage; a pilot port formed in said valve body and communicating with said passage; spool means having opposite axial ends and being shiftable in said internal passage intermediate said end portions between a normal position in which it prevents communication between said external ports, and two operated positions in which it communicates a respective one of said external ports with said pilot port; a pilot flow passage formed in said valve body and bypassing said internal passage and said spool means, said pilot flow passage communicating with said opposite end portions adjacent said opposite axial ends of said spool means, said pilot flow passage having an inlet for a pilot flow at the exterior of said valve body; and orifice means interposed in said pilot flow passage so that a pressure difference may delvelop across said orifice means and is transmitted to said opposite axial ends of said spool means.

Claim 7

A control valve comprising a valve body; an internal passage in said valve body and having opposite end portions; an external input port and an external output port formed in said valve body and each communicating with said internal passage; a pilot port formed in said valve body and communicating with said passage; spool means having opposite axial ends and being shiftable in said internal passage intermediate said end portions between a normal position in which it prevents communication between said external ports, and two operated positions in which it communicates a respective one of said external ports with said pilot port; a pilot flow passage formed in said valve body and bypassing said internal passage and said spool means, said pilot flow passage communicating with said opposite end portions adjacent said opposite axial ends of said spool means, said pilot flow passage having an inlet for a pilot flow at the exterior of said valve body; and orifice means interposed in said pilot flow passage so that a pressure difference may delvelop across said orifice means and is transmitted to said opposite axial ends of said spool means.

Claim 8

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means communicating with said valve chamber and defining two paths for a main fluid flow which pass through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow paths; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow paths located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow paths, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 9

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means communicating with said valve chamber and defining two paths for a main fluid flow which pass through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow paths; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow paths located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow paths, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 10

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; ports means communicating with said valve chamber and defining two paths for a main fluid flow which pass alternately in opposite directions through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow paths; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow paths located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow paths, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 11

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; ports means communicating with said valve chamber and defining two paths for a main fluid flow which pass alternately in opposite directions through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow paths; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow paths located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow paths, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 12

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means communicating with said valve chamber and defining a main fluid flow path which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow path; passage means in said valve body, bypassing said valve chamber and defining a pilot flow path which communicates with said main flow path in the region of said one end of said valve chamber; a first restricted orifice in said main flow path at said one end of said valve chamber, intermediate the latter and said pilot flow path; a second, damper orifice communicating the other end of said valve chamber with said pilot flow passage; and a third orifice in said pilot flow path intermediate said damper orifice and said main flow path.

Claim 13

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means communicating with said valve chamber and defining a main fluid flow path which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow path; passage means in said valve body, bypassing said valve chamber and defining a pilot flow path which communicates with said main flow path in the region of said one end of said valve chamber; a first restricted orifice in said main flow path at said one end of said valve chamber, intermediate the latter and said pilot flow path; a second, damper orifice communicating the other end of said valve chamber with said pilot flow passage; and a third orifice in said pilot flow path intermediate said damper orifice and said main flow path.

Claim 14

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means including a first and a second exterior port, and a third port which communicates with said valve chamber, said first and second ports defining a first path for a first main fluid flow, and said first and third ports defining a second path for a main fluid flow which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said second main fluid flow path; a passage defining a pilot fluid flow path which bypasses said valve chamber; first restricted orifice means interposed in said pilot fluid flow path; second restricted orifice means in said second main fluid flow path located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flows of both of said main fluid flows adjacent said second restricted orifice means, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 15

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means including a first and a second exterior port, and a third port which communicates with said valve chamber, said first and second ports defining a first path for a first main fluid flow, and said first and third ports defining a second path for a main fluid flow which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said second main fluid flow path; a passage defining a pilot fluid flow path which bypasses said valve chamber; first restricted orifice means interposed in said pilot fluid flow path; second restricted orifice means in said second main fluid flow path located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flows of both of said main fluid flows adjacent said second restricted orifice means, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 16

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means including a first and a second port which communicate with one another to form a first main fluid flow path, a third and fourth port both communicating via said valve chamber with said first port and defining second and third main fluid flow paths which pass through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and having a pair of axially spaced apertures in its circumference, said valve spool being slidable in said valve chamber between a position in which communication between said apertures and said third and fourth ports is interrupted, a position in which one of said apertures communicates with said third port, and a position in which the other of said apertures communicates with said fourth port; a passage defining a pilot fluid flow path which bypasses said valve chamber; first restricted orifice means interposed in said pilot fluid flow path; second restricted orifice means in said second and third main fluid flow paths located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flows of all of said main fluid flows adjacent said restricted orifice means for said second and third main fluid flow paths, for controlling the the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 17

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means including a first and a second port which communicate with one another to form a first main fluid flow path, a third and fourth port both communicating via said valve chamber with said first port and defining second and third main fluid flow paths which pass through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and having a pair of axially spaced apertures in its circumference, said valve spool being slidable in said valve chamber between a position in which communication between said apertures and said third and fourth ports is interrupted, a position in which one of said apertures communicates with said third port, and a position in which the other of said apertures communicates with said fourth port; a passage defining a pilot fluid flow path which bypasses said valve chamber; first restricted orifice means interposed in said pilot fluid flow path; second restricted orifice means in said second and third main fluid flow paths located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flows of all of said main fluid flows adjacent said restricted orifice means for said second and third main fluid flow paths, for controlling the the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 18

A hydraulic control valve, caomprising a valve body having a cylindrical valve chamber; a single port communicating with said valve chamber and defining a path for a main fluid flow which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and having a circumferential wall formed with an opening, said valve spool being slidable in said valve chamber between a position in which said opening communicates with said port, and another position in which said opening is out of communication with said port; biasing means biasing said valve spool to said other position; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow path located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow path, for controlling the displacement of said valve spool against the force of said biasing means and the volumetric flow of fluid in the main fluid flow path as a function of the difference between the pressure drops which occur in the fluid flow across said restricted orifice means.

Claim 19

A hydraulic control valve, caomprising a valve body having a cylindrical valve chamber; a single port communicating with said valve chamber and defining a path for a main fluid flow which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and having a circumferential wall formed with an opening, said valve spool being slidable in said valve chamber between a position in which said opening communicates with said port, and another position in which said opening is out of communication with said port; biasing means biasing said valve spool to said other position; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow path located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow path, for controlling the displacement of said valve spool against the force of said biasing means and the volumetric flow of fluid in the main fluid flow path as a function of the difference between the pressure drops which occur in the fluid flow across said restricted orifice means.

Claim 20

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means including a pair of axially spaced ports communicating with said valve chamber and defining two paths for main fluid flows which pass through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and having a circumferential wall formed with a pair of axially spaced openings, said valve spool being slidable in said valve chamber between a position in which said openings are both out of communication with said ports, and positions in which respective ones of said openings communicate with the respective ports; a passage defining a pilot fluid flow path which bypasses said valve chamber but communicates with one of said ports; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow path located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flows of said main fluid flows adjacent said restricted orifice means for said main fluid flow paths, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 21

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means including a pair of axially spaced ports communicating with said valve chamber and defining two paths for main fluid flows which pass through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and having a circumferential wall formed with a pair of axially spaced openings, said valve spool being slidable in said valve chamber between a position in which said openings are both out of communication with said ports, and positions in which respective ones of said openings communicate with the respective ports; a passage defining a pilot fluid flow path which bypasses said valve chamber but communicates with one of said ports; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow path located at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flows of said main fluid flows adjacent said restricted orifice means for said main fluid flow paths, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow paths as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 22

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means communicating with said valve chamber and defining a path for a main fluid flow which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow path; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow path locatEd at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow path, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow path as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.

Claim 23

A hydraulic control valve, comprising a valve body having a cylindrical valve chamber; port means communicating with said valve chamber and defining a path for a main fluid flow which passes through said valve chamber and through one end thereof; a hollow valve spool received in said valve chamber and slidable therein between positions in which it completes and interrupts said main fluid flow path; a passage defining a pilot fluid flow path which bypasses said valve chamber; restricted orifice means interposed in said pilot fluid flow path; restricted orifice means in said main fluid flow path locatEd at said one end of said valve chamber; and conduit means for joining the fluid flow of said pilot fluid flow and the fluid flow of said main fluid flow adjacent said restricted orifice means for said main fluid flow path, for controlling the displacement of said valve spool and the volumetric flow of fluid in the main fluid flow path as a function of the difference between the pressure drops which occur in the fluid flows across said restricted orifice means.