Hydraulic self-leveling control for boom and bucket

Claim 2

A hydraulic system for controlling the related operation of at least a first and second fluid actuated motor, comprising: a pressure fluid supply, a reservoir, and control valve means communicating with the fluid supply, reservoir and first motor; fluid transfer means operatively connected to said control valve means and the second motor to accommodate fluid flow therebetween; a first control element in said control valve means shiftable to a transfer position directing pressure fluid to the first motor to actuate same and directing fluid displaced from the first motor to said transfer means through said control valve means; and flow divider means interposed in said fluid transfer means for directing a predetermined portion of said displaced fluid to the second motor to actuate same in correlation with actuation of the first motor.

Claim 3

The hydraulic system of claim 1 further comprising check valve means located in said fluid transfer means intermediate said flow divider means and the second motor adapted to prevent reverse flow through said transfer means from the second motor to said control valve means.

Claim 4

The hydraulic system of claim 1 further comprising second control valve means communicating with the pressure fluid supply, reservoir and the second motor, said second valve means having an associated second control element shiftable to direct fluid from the pressure fluid supply to the second motor to actuate same and override actuation of the second motor by said predetermined portion of displaced fluid.

Claim 5

The hydraulic system of claim 1 wherein said flow divider means communicates with the reservoir tHrough a discharge duct, and directs the remainder of said displaced fluid to said discharge duct and reservoir.

Claim 6

The hydraulic system of claim 4 wherein said flow divider means includes a first flow restrictor interposed in the flow path from said fluid transfer means to said discharge duct and a second flow restrictor interposed in the flow path from said fluid transfer means to the second motor, the relative sizes of said restrictions determining said portion of displaced fluid directed to the second motor.

Claim 7

The hydraulic system of claim 1 wherein said first motor has opposing variable volume fluid chambers and said first control element is movable to a float position connecting both said chambers and said fluid transfer means with the reservoir.

Claim 8

The hydraulic system of claim 6 wherein said first control element interconnects said fluid transfer means with the reservoir in all positions of said first control element other than said transfer position

Claim 9

The hydraulic system of claim 1 wherein said second motor has opposing variable volume fluid chambers and is actuatable upon introduction of said predetermined portion of displaced fluid into one of said chambers, and said fluid transfer means include a hydraulically operable piston controlling communication between the other of said chambers and the reservoir, said piston movable to an open position connecting said other chamber with the reservoir in response to a predetermined pressure in said fluid transfer means.

Claim 10

The hydraulic system of claim 8 further comprising a check valve in said fluid transfer means intermediate said flow divider means and said one chamber adapted to prevent reverse flow from said one chamber to said control valve means.

Claim 11

A control for a hydraulic power system including a fluid supply, a reservoir, first and second double acting hydraulic motors having movable barriers therein dividing each of said motors into two variable volume chambers, said control comprising: a hydraulic valve assembly operatively connected to said supply and reservoir for supply and return of hydraulic fluid, said valve assembly including first and second control passages connected to actuate said fist motor by delivering and returning hydraulic fluid therefrom and third and forth passages connected to actuate said second motor by delivering and returning hydraulic fluid therefrom; a fluid transfer passage adjacent said first passage and communicating with said third passage; a first control element selectively shiftable to actuate said first motor, having a first position connecting said first passage with said transfer passage and said second passage with said fluid supply whereby fluid discharged from said first motor is delivered to said transfer passage; a second control element shiftable to actuate said second motor and having a neutral position wherein said transfer passage is in communication with one chamber of said second motor through said third passage and the other chamber is in communication with said froth passage; a flow divider interposed in said transfer passage communicating with said reservoir, and being adapted to direct a predetermined portion of flow in said transfer passage to said third passage and directing remaining flow to reservoir; check valve man in said transfer passage intermediate said flow divider and said third passage blocking reverse flow from said third passage to said first passage; and pressure responsive means communicating with said transfer passage controlling communication between said fourth passage and said reservoir, whereby positioning said first control element in said first position and said second element in said neutral position directs fluid to said first motor to actuate same, directs fluid displaced from said first motor through said transfer passage to said flow divider whereby a predetermined portion of said displaced fluid is directed to said second motor to actuate same in correlation with actuation of the fIrst motor, and whereby pressure in said transfer means actuates said pressure responsive means to permit return of flow from said second motor to said reservoir through said fourth passage.

Claim 12

A control for a hydraulic power system including a fluid supply, a reservoir, first and second double acting hydraulic motors having movable barriers therein dividing each of said motors into two variable volume chambers, said control comprising: a hydraulic valve assembly operatively connected to said supply and reservoir for supply and return of hydraulic fluid, said valve assembly including first and second control passages connected to actuate said fist motor by delivering and returning hydraulic fluid therefrom and third and forth passages connected to actuate said second motor by delivering and returning hydraulic fluid therefrom; a fluid transfer passage adjacent said first passage and communicating with said third passage; a first control element selectively shiftable to actuate said first motor, having a first position connecting said first passage with said transfer passage and said second passage with said fluid supply whereby fluid discharged from said first motor is delivered to said transfer passage; a second control element shiftable to actuate said second motor and having a neutral position wherein said transfer passage is in communication with one chamber of said second motor through said third passage and the other chamber is in communication with said froth passage; a flow divider interposed in said transfer passage communicating with said reservoir, and being adapted to direct a predetermined portion of flow in said transfer passage to said third passage and directing remaining flow to reservoir; check valve man in said transfer passage intermediate said flow divider and said third passage blocking reverse flow from said third passage to said first passage; and pressure responsive means communicating with said transfer passage controlling communication between said fourth passage and said reservoir, whereby positioning said first control element in said first position and said second element in said neutral position directs fluid to said first motor to actuate same, directs fluid displaced from said first motor through said transfer passage to said flow divider whereby a predetermined portion of said displaced fluid is directed to said second motor to actuate same in correlation with actuation of the fIrst motor, and whereby pressure in said transfer means actuates said pressure responsive means to permit return of flow from said second motor to said reservoir through said fourth passage.

Claim 13

The control of claim 10 further comprising a pressure relief valve adapted to relieve fluid from said transfer passage to limit pressure therein to a predetermined value.

Claim 14

The control of claim 10 wherein shifting said second control element away from said neutral position to actuate the second motor overrides actuation of the second motor by said predetermined portion of displaced fluid.

Claim 15

A control valve assembly for selectively actuating first and second fluid motors comprising: a housing having a supply passage for connection with a source of pressure fluid, a fluid discharge passage for connection with a low pressure reservoir, and first and second axial bores intercepted at spaced positions by said supply and discharge passages; first and second control passages intersecting said first axial bore and connectable with opposite ends of the first motor; third and fourth control passages intersecting said second axial bore and connectable with opposite end of the second motor; first and second cannelured control spools respectively disposed in said first and second axial bores, each movable to various positions interconnecting said control passages with the inlet and discharge passages for selective actuation to the first and second motors; a transfer passage extending from said third control passage to intercept said first bore intermediate and adjacent said first control passage and said discharge passage, said first spool in a first position interconnecting said first control passage with said transfer passage and blocking same from said discharge passage, and in all other positions interconnecting said transfer passage and said discharge passage; a flow divider comprising a movable body located in the housing in a third axial bore intercepted by said transfer and discharge passages, said body having first and second flow restrictors formed thereon restricting fluid flow from said transfer passage to said third control passage and said discharge passage respectively, whereby a predetermined percentage of flow in said transfer passage is directed through said first restriction to said third control passage and the remainder is directed through said second restriction to said discharge passage; a spring biased check valve in said transfer passage intermediate said flow divider and said third control passage permitting one-way flow through said transfer means from said first control passage to said third control passage; and a hydraulically operable piston biased to a closed position and responsive to a predetermined pressure in said transfer passage to move to an open position interconnecting said fourth control passage with said discharge passage at a position spaced from said first and second axial bores.

Claim 16

A control valve assembly for selectively actuating first and second fluid motors comprising: a housing having a supply passage for connection with a source of pressure fluid, a fluid discharge passage for connection with a low pressure reservoir, and first and second axial bores intercepted at spaced positions by said supply and discharge passages; first and second control passages intersecting said first axial bore and connectable with opposite ends of the first motor; third and fourth control passages intersecting said second axial bore and connectable with opposite end of the second motor; first and second cannelured control spools respectively disposed in said first and second axial bores, each movable to various positions interconnecting said control passages with the inlet and discharge passages for selective actuation to the first and second motors; a transfer passage extending from said third control passage to intercept said first bore intermediate and adjacent said first control passage and said discharge passage, said first spool in a first position interconnecting said first control passage with said transfer passage and blocking same from said discharge passage, and in all other positions interconnecting said transfer passage and said discharge passage; a flow divider comprising a movable body located in the housing in a third axial bore intercepted by said transfer and discharge passages, said body having first and second flow restrictors formed thereon restricting fluid flow from said transfer passage to said third control passage and said discharge passage respectively, whereby a predetermined percentage of flow in said transfer passage is directed through said first restriction to said third control passage and the remainder is directed through said second restriction to said discharge passage; a spring biased check valve in said transfer passage intermediate said flow divider and said third control passage permitting one-way flow through said transfer means from said first control passage to said third control passage; and a hydraulically operable piston biased to a closed position and responsive to a predetermined pressure in said transfer passage to move to an open position interconnecting said fourth control passage with said discharge passage at a position spaced from said first and second axial bores.

Claim 17

The control valve assembly of claim 13 wherein said housing comprises an assembly of section valves including: a first sectional valve having disposed therein said first axial bore, said first control spool, said first and second control passages, said third axial bore and said flow divider; a second sectional valve operatively adjacent said first sectional valve having disposed therein said second axial bore, said second control spool, said third and fourth control passages, said check valve, and said piston; end plates enclosing said sectional valves provided with inlet and outlet openings respectively in communication with said supply and discharge passages in said assembly; and wherein said transfer, supply and discharge passages extend substantially transversely through said sectional valves.

Claim 18

The control valve assembly of claim 13 further including a pressure relief valve in said housing extending between said first control passage and said discharge passage, adapted to divert fluid froM said first control passage to the discharge passage in response to a predetermined pressure in said first control passage to limit pressure therein.

Claim 19

The control valve assembly of claim 15 wherein said housing comprises an assembly of section valves including: a first sectional valve having disposed therein said first axial bore, said first control spool, said first and second control passages, and said pressure relief valve; a second sectional valve having disposed therein said second axial bore, said second control spool, said third and fourth control passages, said check valve, and said piston; a third sectional valve interposed between the first and second sectional valves, having disposed therein said third axial bore and said flow divider; end plates enclosing said sectional valves provided with inlet and outlet openings respectively in communication with said supply and discharge passages in said assembly; and wherein said transfer, supply and discharge passages extend substantially transversely through said sectional valves.

Claim 20

In a hydraulic system including a pump, a reservoir, a first double acting motor having fist and second variable volume fluid chambers, a second double acting motor having third and fourth variable volume fluid chambers, a control valve operatively connected with the pump, reservoir and first motor, and a movable control element mounted in said control valve adapted to connect said first motor fluid chambers with the pump and reservoir to actuate the first motor; wherein the improvement comprises: first fluid transfer means operatively connected with said control valve adapted to interconnect said first and third fluid chambers upon positioning said control element in a first transfer position directing pressure fluid from said pump to said second chamber, whereby displaced fluid from said first chamber flows to said third chamber to actuate the second motor in a first direction; second fluid transfer means operatively connected with said control valve adapted to interconnect said second and fourth fluid chambers upon movement of said control element to a second transfer position directing pressure fluid from said pump to said first chamber, whereby displaced fluid from said second chamber is directed to said fourth chamber to actuate the second motor in a second direction opposite said first direction; a flow divider communicating with the reservoir and interposed in said first fluid transfer means to direct a predetermined portion of fluid flow therein to a said third chamber and divert the remainder of fluid flow in said first fluid transfer means to reservoir; and discharge means connected with said second motor and the reservoir operative upon movement of said control element to said first transfer position to interconnect said fourth chamber with the reservoir, and operative upon movement of said control element to said second transfer position to interconnnect said third chamber with the reservoir.

Claim 21

In a hydraulic system including a pump, a reservoir, a first double acting motor having fist and second variable volume fluid chambers, a second double acting motor having third and fourth variable volume fluid chambers, a control valve operatively connected with the pump, reservoir and first motor, and a movable control element mounted in said control valve adapted to connect said first motor fluid chambers with the pump and reservoir to actuate the first motor; wherein the improvement comprises: first fluid transfer means operatively connected with said control valve adapted to interconnect said first and third fluid chambers upon positioning said control element in a first transfer position directing pressure fluid from said pump to said second chamber, whereby displaced fluid from said first chamber flows to said third chamber to actuate the second motor in a first direction; second fluid transfer means operatively connected with said control valve adapted to interconnect said second and fourth fluid chambers upon movement of said control element to a second transfer position directing pressure fluid from said pump to said first chamber, whereby displaced fluid from said second chamber is directed to said fourth chamber to actuate the second motor in a second direction opposite said first direction; a flow divider communicating with the reservoir and interposed in said first fluid transfer means to direct a predetermined portion of fluid flow therein to a said third chamber and divert the remainder of fluid flow in said first fluid transfer means to reservoir; and discharge means connected with said second motor and the reservoir operative upon movement of said control element to said first transfer position to interconnect said fourth chamber with the reservoir, and operative upon movement of said control element to said second transfer position to interconnnect said third chamber with the reservoir.

Claim 22

The hydraulic system of claim 17 further including a second flow divider communicating with the reservoir and interposed in said second fluid transfer means to direct a predetermined portion of fluid flow therein to said fourth chamber and divert the remainder of fluid flow in said second transfer means to reservoir.

Claim 23

The hydraulic system of claim 18 wherein said first transfer means includes a first check valve located intermediate the first flow divider and said third chamber biased to a closed position blocking flow therebetween and responsive to a predetermined pressure in said first transfer means to move to an open position, and wherein said second transfer means includes a second check valve located intermediate said second flow divider and said fourth chamber biased to a closed position blocking flow therebetween and responsive to a predetermined pressure in said second transfer means to move to an open position.

Claim 24

The hydraulic system of claim 19 wherein said control element connects said second transfer means with the reservoir in said first transfer position, and said discharge means include: a plunger operably engaging said second check valve and adapted to open same in response to said predetermined pressure in said first transfer means; a bypass passage connected with said second transfer means in parallel with said second flow divider; and a unidirectional valve in said bypass passage blocking flow therethrough from said control valve to said second motor, whereby in said first transfer position pressure in said first transfer means opens said second check valve to establish a flow path from said fourth passage through said second transfer means and said bypass passage to the reservoir.

Claim 25

In a hydraulic valve assembly including a body having first and second axial bores intersected by a pressure inlet connected to a pump and a fluid outlet connected to a reservoir, first and second control passages intersecting the first axial bore and connected to expanding and contracting chambers of a first double acting motor, third and fourth control passages intersecting the second axial bore and connected to expanding and contracting chambers of a second double acting motor, and first and second spools mounted in said first and second axial bores respectively and shiftable away from neutral to positions directing fluid to and from said control passages to actuate said motors, wherein the improvement comprises: first and second fluid transfer circuits in said assembly extending from said first axial bore to said third and fourth control passages respectively; a said first spool having transfer positions for actuating both said motors wherein the first spool is adapted to simultaneously connect the inlet with the expanding chamber of the first motor to actuate same, one transfer circuit with the contracting chamber of the first motor to transfer fluid displaced therefrom as actuating flow to the expanding chamber of the second motor, and the other transfer circuit with the outlet to transfer to reservoir the return flow displaced from the contracting chamber of the second motor; a flow divider interposed in each transfer circuit and communicating with the outlet adapted to direct a preselected portion of said transfer actuating flow to said second motor and the remainder to the outlet whereby the second motor is actuated in predetermined correlation with the first motor; a bypass conduit communicating with each transfer circuit and arranged parallel to said flow dividers to permit said transfer return flow to bypass said flow dividers; a unidirectional flow valve interposed in each bypass conduit permitting only said transfer return flow therethrough; and a check valve in each transfer circuit located intermediate the second motor and the bypass conduit openable in response to pressure in either of the transfer circuits when said second spool is in neutral, and responsive to a shift of said second spool away from neutral to move to a closed position blocking transmittal of said transfer actuating flow to the second motor.

Claim 26

In a hydraulic valve assembly including a body having first and second axial bores intersected by a pressure inlet connected to a pump and a fluid outlet connected to a reservoir, first and second control passages intersecting the first axial bore and connected to expanding and contracting chambers of a first double acting motor, third and fourth control passages intersecting the second axial bore and connected to expanding and contracting chambers of a second double acting motor, and first and second spools mounted in said first and second axial bores respectively and shiftable away from neutral to positions directing fluid to and from said control passages to actuate said motors, wherein the improvement comprises: first and second fluid transfer circuits in said assembly extending from said first axial bore to said third and fourth control passages respectively; a said first spool having transfer positions for actuating both said motors wherein the first spool is adapted to simultaneously connect the inlet with the expanding chamber of the first motor to actuate same, one transfer circuit with the contracting chamber of the first motor to transfer fluid displaced therefrom as actuating flow to the expanding chamber of the second motor, and the other transfer circuit with the outlet to transfer to reservoir the return flow displaced from the contracting chamber of the second motor; a flow divider interposed in each transfer circuit and communicating with the outlet adapted to direct a preselected portion of said transfer actuating flow to said second motor and the remainder to the outlet whereby the second motor is actuated in predetermined correlation with the first motor; a bypass conduit communicating with each transfer circuit and arranged parallel to said flow dividers to permit said transfer return flow to bypass said flow dividers; a unidirectional flow valve interposed in each bypass conduit permitting only said transfer return flow therethrough; and a check valve in each transfer circuit located intermediate the second motor and the bypass conduit openable in response to pressure in either of the transfer circuits when said second spool is in neutral, and responsive to a shift of said second spool away from neutral to move to a closed position blocking transmittal of said transfer actuating flow to the second motor.