Hydraulic motor fluid flow circuitry

Claim 2

A hydrostatic drive system comprising: a hydraulic motor including a housing having first, second and third ports, an output shaft mounted for rotation, means in a primary fluid circuit disposed in said housing between said first and second ports and connected to said shaft for causing rotation of said shaft in response to fluid flow therethrough, a secondary fluid circuit disposed in said housing between said primary fluid circuit and said third port, and valve means in said secondary fluid circuit for bypassing a portion of the fluid received in said primary fluid circuit out of said housing through said third port; a first pump including three ports and operable to discharge fluid at a first flow rate from a second of said ports, at a second flow rate from a third of said ports and receive fluid at said first and second flow rates combined at a first of said ports; a heat exchanger connected to receive the fluid discharged from said third ports of said motor and said first pump for cooling and discharging the fluid; a reservoir connected to receive the fluid discharged from said heat exchanger; and a second pump connected between said reservoir and said first pump for providing said pump with fluid equal to the fluid cooled in said heat exchanger.

Claim 3

The hydrostatic drive system set forth in claim 1, comprising: a first check valve connected between said second pump and said first port of said first pump; and a second check valve connected between said second pump and said second port of said first pump, said check valves respectively operable to pass fluid from said second pump to the low pressure fluid receiving one of said first and second ports of said first pump.

Claim 4

The hydrostatic drive system set forth in claim 1, wherein said valve means comprises: a first fluid passage extending between two points in said first fluid circuit of different pressure, a second fluid passage extending from said first fluid passage to said third port of said motor, and first and second valves in said first fluid passage on opposite sides of the point of communication with said second fluid passage and respectively operable in response to opposite directions of the pressure differential between said two points.

Claim 5

A reversible hydraulic motor comprising a housing having first, second and third ports, said first port serving as an inlet port for receiving fluid at a relatively high pressure during operation of said motor in a first direction and serving as an outlet port for discharging fluid at a relatively low pressure during operation of said motor in a second direction, said second port serving as an outlet port for discharging fluid at a relatively low pressure during operation of said motor in the first direction and serving as an inlet port for receiving fluid at a relatively high pressure during operation of said motor in the second direction, a rotatable output shaft extending from said housing, a primary fluid circuit in said housing extending between said first and second ports, said primary fluid circuit including drive means connected with said shaft for causing rotation of said shaft in response to fluid flow through said drive means, first passage means disposed in said housing for conducting fluid at a relatively high pressure from Said first port to said drive means during operation of said motor in the first direction and for conducting fluid at a relatively low pressure from said drive means to said first port during operation of said motor in the second direction, and second passage means disposed in said housing for conducting fluid at a relatively low pressure from said drive means to said second port during operation of said motor in the first direction and for conducting fluid at a relatively high pressure from said second port to said drive means during operation of said motor in the second direction, and a secondary fluid circuit disposed in said housing and extending between said primary fluid circuit and said third port, said secondary fluid circuit including valve means disposed in said housing for bypassing a portion of the fluid traversing said primary fluid circuit to said third port during fluid flow through said primary fluid circuit, third passage means disposed in said housing for conducting fluid at a relatively low pressure from said second passage means to said valve means during operation of said motor in the first direction, fourth fluid passage means disposed in said housing for conducting fluid at a relatively low pressure from said first passage means to said valve means during operation of said motor in the second direction, and fifth passage means disposed in said housing for conducting fluid at a relatively low fluid pressure from said valve means to said third port during operation of said motor in the first and second directions.

Claim 6

A reversible hydraulic motor comprising a housing having first, second and third ports, said first port serving as an inlet port for receiving fluid at a relatively high pressure during operation of said motor in a first direction and serving as an outlet port for discharging fluid at a relatively low pressure during operation of said motor in a second direction, said second port serving as an outlet port for discharging fluid at a relatively low pressure during operation of said motor in the first direction and serving as an inlet port for receiving fluid at a relatively high pressure during operation of said motor in the second direction, a rotatable output shaft extending from said housing, a primary fluid circuit in said housing extending between said first and second ports, said primary fluid circuit including drive means connected with said shaft for causing rotation of said shaft in response to fluid flow through said drive means, first passage means disposed in said housing for conducting fluid at a relatively high pressure from Said first port to said drive means during operation of said motor in the first direction and for conducting fluid at a relatively low pressure from said drive means to said first port during operation of said motor in the second direction, and second passage means disposed in said housing for conducting fluid at a relatively low pressure from said drive means to said second port during operation of said motor in the first direction and for conducting fluid at a relatively high pressure from said second port to said drive means during operation of said motor in the second direction, and a secondary fluid circuit disposed in said housing and extending between said primary fluid circuit and said third port, said secondary fluid circuit including valve means disposed in said housing for bypassing a portion of the fluid traversing said primary fluid circuit to said third port during fluid flow through said primary fluid circuit, third passage means disposed in said housing for conducting fluid at a relatively low pressure from said second passage means to said valve means during operation of said motor in the first direction, fourth fluid passage means disposed in said housing for conducting fluid at a relatively low pressure from said first passage means to said valve means during operation of said motor in the second direction, and fifth passage means disposed in said housing for conducting fluid at a relatively low fluid pressure from said valve means to said third port during operation of said motor in the first and second directions.

Claim 7

A reversible hydraulic motor as set forth in claim 4 wherein said valve means is actuatable under the influence of fluid pressure to a first condition upon operation of said motor in the first direction and is actuatable under the influence of fluid pressure to a second condition upon operation of said motor in the second direction, said valve means being effective to block fluid flow from said fourth passage means to said fifth passage means and to enable fluid to flow from said third passage means to said fifth passage means when said valve means is in the first condition, said valve means being effective to block fluid flow from said third passage means to said fifth passage means and to enable fluid to flow from said fourth passage means to said fifth passage means when said valve means is in the second condition.

Claim 8

A reversible hydraulic motor as set forth in claim 4 wherein said valve means includes a first valve seat disposed in said housing and connected in fluid communication with said third and fifth passage means, a second valve seat disposed in said housing and connected in fluid communication with said fourth and fifth passage means, a first valve member disposed in said housing and movable between an open condition spaced apart from said first valve seat and a closed condition disposed in sealing engagement with said first valve seat, a second valve member disposed in said housing and movable between an open condition spaced apart from said second valve seat and a closed condition disposed in sealing engagement with said second valve seat, and means interconnecting said valve members for moving one of said valve members from the open condition to the closed condition upon movement of the other valve member from the closed condition to the open condition.

Claim 9

A reversible hydraulic motor as set forth in claim 6 wherein said first and second valve members have a generally spherical configuration and said means interconnecting said valve members includes a rod having one end portion connected with the first valve member and another end portion connected with the second valve member.

Claim 10

A reversible hydraulic motor as set forth in claim 6 comprising means for biasing both of said valve members away from their respective seats until flow restriction increases sufficiently to close one of the valves to establish a dead band flow.

Claim 11

A reversible hydraulic motor as set forth in claim 8 wherein said biasing means comprises a paIr of springs each disposed between a respective valve member and stationary wall of an associated one of said passages.