Hydraulic motors and driving systems employing same

Claim 2

An hydraulic motor having means for receiving an externally generated fluid pressure signal and having: a stationary casing having a fluid pressure inlet and an exhaUst fluid outlet, said casing comprising a stationary casing part presenting at least two rings of ports; a rotor comprising at least two rows of pistons and cylinders; and rotatable about said stationary casing part, the pistons being reciprocable in their cylinders by the action of fluid under pressure supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports to thereby rotate the rotor; and adjustable valve means for communicating the pressure fluid inlet and the exhaust fluid outlet with different numbers of said rows of ports, the valve means comprising only a single displaceable valve member which is slideable in said casing so as to be selectively adjustable, linearly, in two opposite directions by fluid under pressure between two alternative positions, said valve member being displaceable in one direction in response to the fluid pressure signal supplied to the motor and acting on a first effective area of the valve member, and being displaceable in the other direction by the supply of working fluid to the motor and acting on a lesser effective area of the valve member which is oppositely directed to said first effective area of the valve member, said valve means controlling the supply of the working fluid to the motor by selectively communicating said pressure fluid inlet and an exhaust fluid outlet of the motor respectively with a first number of said rows when in a first of said two alternative positions and with a second number of said rows which is greater than said first number of said rows when in the other of said two alternative positions, to provide for two different motor speeds for a given delivery of working fluid to the motor, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions.

Claim 3

An hydraulic motor as claimed in claim 1 wherein the valve means is responsive to a cessation of said fluid pressure signal supplied to the motor to operate the motor at one of said two different motor speeds for said given delivery of working fluid to the motor.

Claim 4

An hydraulic motor as claimed in claim 2 wherein in the absence of said fluid pressure signal the valve means is responsive to fluid under pressure supplied into said pressure fluid inlet to operate the motor at said one of said two different motor speeds for said given delivery of working fluid to the motor.

Claim 5

An hydraulic motor as claimed in claim 1 wherein the valve means is adjustable to connect the non-operative row or rows of pistons and cylinders with the exhaust fluid outlet.

Claim 6

An hydraulic motor as claimed in claim 1 wherein the valve means is adjustable to connect the non-operative row or rows of pistons and cylinders with a space within the motor casing vented to atmospheric pressure.

Claim 7

An hydraulic motor as claimed in claim 5 wherein said space is sealed with respect to the outer ends of the pistons and the piston outer ends are subject to the pressure in a further space within the motor casing.

Claim 8

An hydraulic motor as claimed in claim 6 wherein the piston outer ends carry cam followers which normally engage a cam track at least in part bounding said further space, the followers being tethered to the pistons and the pistons being movable to the inner ends of the cylinders to withdraw the followers out of engagement with said track.

Claim 9

An hydraulic motor as claimed in claim 3 wherein said linearly displaceable valve member is concentric with the axis of rotation of the rotor and is displaceable along said axis, the member defining a first space between one end face of the valve member and the casing, a fluid conduit is provided communicating said first space with the outside of the motor casing for conducting said fluid pressure signal into said space, said valve member being subject to the pressure of fluid in said pressure fluid inlet or said exhaust fluid outlet on a face opposite said one end face of the valve member, which opPosite face is of an effective area less than said one end face.

Claim 10

An hydraulic motor as claimed in claim 8 wherein the valve member is a valve spool and the valve spool is slidable axially on said conduit which is disposed co-axially with the valve spool.

Claim 11

An hydraulic motor as claimed in claim 9 wherein the valve member supports said conduit at one end thereof.

Claim 12

An hydraulic motor as claimed in claim 5 wherein the valve member defines with the motor casing a second space which is brought into communication with inlet and outlet ports of said row or rows of pistons and cylinders when the valve member is displaced by said fluid pressure signal, thereby to render said row or rows of pistons and cylinders non-operative, and passage means is provided communicating said inlet and outlet ports through said second space with said space within said motor casing which is vented to atmosphere.

Claim 13

A driving system comprising a main hydraulic pump connected in a closed-loop to supply fluid under pressure to an hydraulic motor comprising a stationary casing having a fluid pressure inlet and an exhaust fluid outlet, said casing comprising a stationary casing part presenting two rings of ports; a rotor comprising two rows of pistons and cylinders and rotatable about said stationary casing part; the pistons being reciprocable in their cylinders by the action of fluid under pressure supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports thereby to rotate the rotor; and valve means comprising only a single displaceable valve member which is slideable in said casing so as to be adjustable in response to an external fluid pressure signal, linearly, in two opposite directions between two alternative positions to communicate said pressure fluid inlet and said exhaust fluid outlet of the motor alternatively with one and both of said rings of ports to thereby operate said one or both of the rows of pistons and cylinders to provide two different motor speeds for a given delivery of working fluid to the motor, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions said valve means, when adjusted to said first alternative position, communicates said pressure fluid inlet and said exhaust fluid outlet with said one of said rows of pistons and cylinders while communicating the other row of pistons and cylinders with a space within the motor casing vented to atmospheric pressure, said space being sealed with respect to the outer ends of the pistons and the piston outer ends being subject to the pressure in a further space within the motor casing, the piston outer ends carrying cam followers which normally engage a cam track at least in part bounding said further space, the followers being tethered to the pistons and the pistons being movable to the inner ends of the cylinders to withdraw the followers out of engagement with said track, and a booster pump connected to said loop to boost the inlet pressure to said main hydraulic pump, and to pressurize said further space when said other row of pistons and cylinders is non-operative.

Claim 14

A driving system comprising a main hydraulic pump connected in a closed-loop to supply fluid under pressure to an hydraulic motor comprising a stationary casing having a fluid pressure inlet and an exhaust fluid outlet, said casing comprising a stationary casing part presenting two rings of ports; a rotor comprising two rows of pistons and cylinders and rotatable about said stationary casing part; the pistons being reciprocable in their cylinders by the action of fluid under pressure supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports thereby to rotate the rotor; and valve means comprising only a single displaceable valve member which is slideable in said casing so as to be adjustable in response to an external fluid pressure signal, linearly, in two opposite directions between two alternative positions to communicate said pressure fluid inlet and said exhaust fluid outlet of the motor alternatively with one and both of said rings of ports to thereby operate said one or both of the rows of pistons and cylinders to provide two different motor speeds for a given delivery of working fluid to the motor, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions said valve means, when adjusted to said first alternative position, communicates said pressure fluid inlet and said exhaust fluid outlet with said one of said rows of pistons and cylinders while communicating the other row of pistons and cylinders with a space within the motor casing vented to atmospheric pressure, said space being sealed with respect to the outer ends of the pistons and the piston outer ends being subject to the pressure in a further space within the motor casing, the piston outer ends carrying cam followers which normally engage a cam track at least in part bounding said further space, the followers being tethered to the pistons and the pistons being movable to the inner ends of the cylinders to withdraw the followers out of engagement with said track, and a booster pump connected to said loop to boost the inlet pressure to said main hydraulic pump, and to pressurize said further space when said other row of pistons and cylinders is non-operative.

Claim 15

A driving system as claimed in claim 12 wherein the main hydraulic pump is a variable delivery pump.

Claim 16

A driving system as claimed in claim 12 wherein the booster pump is connected through a non-return valve into the hydraulic loop on the inlet side of the main hydraulic pump and through a non-return valve into the hydraulic loop on the discharge side of the main hydraulic pump, a two-position selector valve is provided which has one position in which it communicates the discharge side of the pump through a non-return valve with said fluid conduit to supply said fluid pressure signal thereto, said selector valve, in its said one position, connecting the booster pump with said further space within the motor casing, the selector valve, in its other position, connecting said fluid pressure conduit with the booster pUmp which operates at a discharge pressure less than the main hydraulic pump.

Claim 17

A driving system as claimed in claim 14 wherein the booster pump supplies boost pressure valve through a boost pressure relief valve to pressurise said further space within the motor casing, and the fluid flow to that space return to tank via a restriction and a non-return pressure relief valve connected in parallel with one another, the restriction being selected such that in said other position of the selector valve the pressure in said further space is substantially relieved, the boost pressure overcoming the leakage flow through said restriction when the selector valve is in its said one position to build up pressure in said further space sufficient to move the pistons to the inner ends of the cylinders and withdraw the followers out of engagement with the cam track as aforesaid.

Claim 18

A driving system as claimed in claim 12 wherein the booster pump is connected through a non-return valve into the hydraulic loop on the inlet side of the main hydraulic pump and through a non-return valve into the hydraulic loop on the discharge side of the main hydraulic pump, a two-position selector valve is provided which has one position in which it communicates the discharge side of the pump through a non-return valve with said fluid conduit to supply said fluid pressure signal thereto, the booster pump being connected with said further space within the motor casing through a boost pressure relief valve, the fluid flow to that space returning to tank via a non-return pressure relief valve, the selector valve in its other position, connecting said fluid pressure conduit with the booster pump which operates at a discharge pressure less than the main hydraulic pump, the boost pump pressure overcoming said non-return pressure relief valve to build up pressure in said further space sufficient to move the pistons to the inner ends of the cylinders and withdraw the followers out of engagement with the cam track as aforesaid.

Claim 19

A driving system as claimed in claim 14 wherein said selector valve in its said one position restricts the flow of pressure fluid to said fluid conduit whereby said valve means is adjusted slowly.

Claim 20

A driving system comprising a variable delivery pump connected to supply fluid under pressure to an hydraulic motor having a rotor comprising two rows of pistons and cylinders and valve means for supplying fluid under pressure into the cylinders and for allowing it to exhaust therefrom, thereby to drive the pistons and rotate the rotor, the valve means being adjustable responsive to an external fluid pressure signal to communicate a pressure fluid inlet and an exhaust fluid outlet of the motor alternatively with one and both of said rows of pistons and cylinders to thereby operate said one or both the rows of pistons and cylinders to provide two different motor speeds for a given delivery of working fluid to the motor, said motor and said pump being connected in closed loop hydraulic system including a booster pump to make up the system leakage, said valve means being adjustable in response to a fluid pressure signal supplied to the motor to operate the motor in one of its two modes of operation, and in response to a cessation of said fluid pressure signal supplied to the motor, to operate the motor in the other of its two modes of operation, the valve means being adjustable, in the absence of said fluid pressure signal, by fluid under pressure supplied into said pressure fluid inlet to operate the motor in said other of its two modes, the valve means comprising a linearly displaceable valve member defining a first space between one end face of the valve member and the motor casing, a fluid conduit being provided communicating said first space into the outside of the motor casing for conducting said fluid pressure signal into said space, said valve member being subject to the pressure of fluid in said inlet or a face opposite said one end face of the valve member which oppOsite face is of an effective area less than said one end face, and the booster pump is connected through a non-return valve into the hydraulic loop on the inlet side of the variable delivery pump and through a non-return valve into the hydraulic loop on the discharge side of the hydraulic pump, the booster pump being additionally connected through a two-position selector valve to supply, in one position of said selector valve, said fluid pressure signal to said fluid conduit, the selector valve, in its other position, connecting said fluid conduit with said hydraulic loop between the discharge side of said variable delivery pump and the pressure fluid inlet to the motor via a non-return valve.

Claim 21

A driving system comprising a variable delivery pump connected to supply fluid under pressure to an hydraulic motor having a rotor comprising two rows of pistons and cylinders and valve means for supplying fluid under pressure into the cylinders and for allowing it to exhaust therefrom, thereby to drive the pistons and rotate the rotor, the valve means being adjustable responsive to an external fluid pressure signal to communicate a pressure fluid inlet and an exhaust fluid outlet of the motor alternatively with one and both of said rows of pistons and cylinders to thereby operate said one or both the rows of pistons and cylinders to provide two different motor speeds for a given delivery of working fluid to the motor, said motor and said pump being connected in closed loop hydraulic system including a booster pump to make up the system leakage, said valve means being adjustable in response to a fluid pressure signal supplied to the motor to operate the motor in one of its two modes of operation, and in response to a cessation of said fluid pressure signal supplied to the motor, to operate the motor in the other of its two modes of operation, the valve means being adjustable, in the absence of said fluid pressure signal, by fluid under pressure supplied into said pressure fluid inlet to operate the motor in said other of its two modes, the valve means comprising a linearly displaceable valve member defining a first space between one end face of the valve member and the motor casing, a fluid conduit being provided communicating said first space into the outside of the motor casing for conducting said fluid pressure signal into said space, said valve member being subject to the pressure of fluid in said inlet or a face opposite said one end face of the valve member which oppOsite face is of an effective area less than said one end face, and the booster pump is connected through a non-return valve into the hydraulic loop on the inlet side of the variable delivery pump and through a non-return valve into the hydraulic loop on the discharge side of the hydraulic pump, the booster pump being additionally connected through a two-position selector valve to supply, in one position of said selector valve, said fluid pressure signal to said fluid conduit, the selector valve, in its other position, connecting said fluid conduit with said hydraulic loop between the discharge side of said variable delivery pump and the pressure fluid inlet to the motor via a non-return valve.

Claim 22

An hydraulic motor as claimed in claim 1 comprising only two rows of pistons and cylinders.

Claim 23

An hydraulic motor having means for receiving an externally generated fluid pressure signal and having: a stationary casing having a fluid pressure inlet and an exhaust fluid outlet, said casing comprising a stationary casing part presenting at least two rings of ports; a rotor comprising at least two rows of pistons and cylinders and rotatable about said stationary casing part, the pistons being reciprocable in their cylinders by the action of fluid under pressure supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports thereby to rotate the rotor; adjustable valve means for communicating the pressure fluid inlet and the exhaust fluid outlet with different numbers of said rows of ports, the valve means comprising only a single displaceable valve member which is slideable in said casing so as to be selectively adjustable, linearly, in two opposite directions between two alternative positions and in one direction in response to the fluid pressure signal supplied to the motor, said linearly displaceable valve member being concentric with the axis of rotation of the rotor and being displaceable along said axis, said valve member defining a first space between one end face of the valve member and the casing; and a fluid conduit communicating said first space with the outside of the motor casing for conducting said fluid pressure signal into said space, said valve member being subject to the pressure of fluid in said pressure fluid inlet or said exhaust fluid outlet on a face opposite said one end face of the valve member, which opposite face is of an effective area less than said one end face; said valve means controlling the supply of the working fluid to the motor by selectively communicating said pressure fluid inlet and said exhaust fluid outlet of the motor respectively with a first number of said rows when in a first of said two alternative positions and with a second number of said rows which is greater than said first number of said rows when in the other of said two alternative positions, to provide for two different motor speeds for a given delivery of working fluid to the motor, said valve means being responsive to a cessation of said fluid pressure signal supplied to the motor to operate the motor at one of said two different motor speeds for said given delivery of working fluid to the motor, and in the absence of said fluid pressure signal the valve means is responsive to fluid under pressure supplied into said pressure fluid inlet to operate the motor at said one of said two different motor speeds, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions.

Claim 24

An hydraulic motor having means for receiving an externally generated fluid pressure signal and having: a stationary casing having a fluid pressure inlet and an exhaust fluid outlet, said casing comprising a stationary casing part presenting at least two rings of ports; a rotor comprising at least two rows of pistons and cylinders and rotatable about said stationary casing part, the pistons being reciprocable in their cylinders by the action of fluid under pressure supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports thereby to rotate the rotor; adjustable valve means for communicating the pressure fluid inlet and the exhaust fluid outlet with different numbers of said rows of ports, the valve means comprising only a single displaceable valve member which is slideable in said casing so as to be selectively adjustable, linearly, in two opposite directions between two alternative positions and in one direction in response to the fluid pressure signal supplied to the motor, said linearly displaceable valve member being concentric with the axis of rotation of the rotor and being displaceable along said axis, said valve member defining a first space between one end face of the valve member and the casing; and a fluid conduit communicating said first space with the outside of the motor casing for conducting said fluid pressure signal into said space, said valve member being subject to the pressure of fluid in said pressure fluid inlet or said exhaust fluid outlet on a face opposite said one end face of the valve member, which opposite face is of an effective area less than said one end face; said valve means controlling the supply of the working fluid to the motor by selectively communicating said pressure fluid inlet and said exhaust fluid outlet of the motor respectively with a first number of said rows when in a first of said two alternative positions and with a second number of said rows which is greater than said first number of said rows when in the other of said two alternative positions, to provide for two different motor speeds for a given delivery of working fluid to the motor, said valve means being responsive to a cessation of said fluid pressure signal supplied to the motor to operate the motor at one of said two different motor speeds for said given delivery of working fluid to the motor, and in the absence of said fluid pressure signal the valve means is responsive to fluid under pressure supplied into said pressure fluid inlet to operate the motor at said one of said two different motor speeds, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions.

Claim 25

An hydraulic motor as claimed in claim 20 wherein the valve member is a valve spool and the valve spool is slidable axially on said conduit which is disposed co-axially with the valve spool.

Claim 26

An hydraulic motor as claimed in claim 21 wherein the valve member supports said conduit at one end thereof.

Claim 27

An hydraulic motor having means for receiving an externally generated fluid pressure signal and having: a stationary casing having a fluid pressUre inlet and an exhaust fluid outlet, said casing comprising a stationary casing part presenting at least two rings of ports; a rotor comprising at least two rows of pistons and cylinders and rotatable about said stationary casing part, the pistons being reciprocable in their cylinders by the action of fluid supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports thereby to rotate the rotor; and adjustable valve means for communicating the pressure fluid inlet and the exhaust fluid outlet with different numbers of said rows of ports, the valve means comprising only a single displaceable valve member which is slideable in said casing so as to be selectively adjustable, linearly, in two opposite directions between two alternative positions and in one direction in response to the fluid pressure signal supplied to the motor; said valve means controlling the supply of the working fluid to the motor by selectively connecting said pressure fluid inlet and said exhaust fluid outlet of the motor respectively with (i) a first number of said rows when in a first of said two alternative positions and connecting the non-operative pistons and cylinders with a space within the motor casing vented to atmospheric pressure, and (ii) with a second number of said rows which is greater than said first number of said rows when in the other of said two alternative positions, to provide for two different motor speeds for a given delivery of working fluid to the motor; said valve member defining with the motor casing a second space which is brought into communication with inlet and outlet ports of said row or rows of pistons and cylinders when the valve member is displaced by said fluid pressure signal, thereby to render said row or rows of pistons and cylinders non-operative, and passage means is provided communicating said inlet and outlet ports through said second space with said space within said motor casing which is vented to atmosphere, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions.

Claim 28

An hydraulic motor having means for receiving an externally generated fluid pressure signal and having: a stationary casing having a fluid pressUre inlet and an exhaust fluid outlet, said casing comprising a stationary casing part presenting at least two rings of ports; a rotor comprising at least two rows of pistons and cylinders and rotatable about said stationary casing part, the pistons being reciprocable in their cylinders by the action of fluid supplied into and exhausted from the cylinders of each row of cylinders respectively through said rings of ports thereby to rotate the rotor; and adjustable valve means for communicating the pressure fluid inlet and the exhaust fluid outlet with different numbers of said rows of ports, the valve means comprising only a single displaceable valve member which is slideable in said casing so as to be selectively adjustable, linearly, in two opposite directions between two alternative positions and in one direction in response to the fluid pressure signal supplied to the motor; said valve means controlling the supply of the working fluid to the motor by selectively connecting said pressure fluid inlet and said exhaust fluid outlet of the motor respectively with (i) a first number of said rows when in a first of said two alternative positions and connecting the non-operative pistons and cylinders with a space within the motor casing vented to atmospheric pressure, and (ii) with a second number of said rows which is greater than said first number of said rows when in the other of said two alternative positions, to provide for two different motor speeds for a given delivery of working fluid to the motor; said valve member defining with the motor casing a second space which is brought into communication with inlet and outlet ports of said row or rows of pistons and cylinders when the valve member is displaced by said fluid pressure signal, thereby to render said row or rows of pistons and cylinders non-operative, and passage means is provided communicating said inlet and outlet ports through said second space with said space within said motor casing which is vented to atmosphere, the pressure fluid inlet and the exhaust fluid outlet being interchangeable to rotate the rotor in opposite directions.