Hydraulic cooling system

Claim 2

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, motor outlet pressure-sensing means including passage means interconnecting the outlet side of said motor and said valve means in a manner such that outlet fluid pressure acts on said valve means in a direction tending to increase said inlet pressure.

Claim 3

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: pressure-regulating means for controlling the differential pressure across said motor, said pressure-regulating means including differential pressure-sensing means sensitive to differential pressure across said motor and operable to increase said differential pressure upon a reduction in said differential pressure below a predetermined demand differential pressure necessary to maintain a predetermined fan speed and operable to decrease said differential presSure upon an increase in differential pressure above said demand differential pressure, and temperature-responsive means operable to increase the demand pressure setting of said pressure-regulating means upon an increase in system temperature and operable to decrease said demand pressure setting upon a reduction in system temperature.

Claim 4

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: pressure-regulating means for controlling the differential pressure across said motor, said pressure-regulating means including differential pressure-sensing means sensitive to differential pressure across said motor and operable to increase said differential pressure upon a reduction in said differential pressure below a predetermined demand differential pressure necessary to maintain a predetermined fan speed and operable to decrease said differential presSure upon an increase in differential pressure above said demand differential pressure, and temperature-responsive means operable to increase the demand pressure setting of said pressure-regulating means upon an increase in system temperature and operable to decrease said demand pressure setting upon a reduction in system temperature.

Claim 5

A system according to claim 2 including a second fluid motor connected in series with said fan motor, said pressure-regulating means being connected in series with said second fluid motor.

Claim 6

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said valve means comprising a thermo-modulated pressure relief valve means including: a pilot valve sensitive to variations in differential pressure across said motor controlling a pilot flow of fluid, and a primary valve for controlling a primary flow of fluid, said temperature-sensing means including an expansible thermal element operably connected to said pilot valve for controlling said pilot flow in response to temperature sensings of said element, said pilot flow being operable to control the positioning of said primary valve and thus the primary flow and degree of pressure relief.

Claim 7

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said valve means comprising a thermo-modulated pressure relief valve means including: a pilot valve sensitive to variations in differential pressure across said motor controlling a pilot flow of fluid, and a primary valve for controlling a primary flow of fluid, said temperature-sensing means including an expansible thermal element operably connected to said pilot valve for controlling said pilot flow in response to temperature sensings of said element, said pilot flow being operable to control the positioning of said primary valve and thus the primary flow and degree of pressure relief.

Claim 8

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said valve means comprising a thermo-modulated pressure relief valve means including: a valve member positionable for controlling fluid flow through said valve means and thereby the degree of pressure relief, said valve member being responsive to differential pressure across said motor means independently of system pressure under normal system pressures, said temperature-sensing means including means operable to modulate the position of said valve member in response to temperature-sensings of said sensing means, and pressure override means operable under predetermined abnormal system pressures to determine the position of said valve member independently of said temperature-sensing means and the differential pressure across said motor means.

Claim 9

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said valve means comprising a thermo-modulated pressure relief valve means including: a valve member positionable for controlling fluid flow through said valve means and thereby the degree of pressure relief, said valve member being responsive to differential pressure across said motor means independently of system pressure under normal system pressures, said temperature-sensing means including means operable to modulate the position of said valve member in response to temperature-sensings of said sensing means, and pressure override means operable under predetermined abnormal system pressures to determine the position of said valve member independently of said temperature-sensing means and the differential pressure across said motor means.

Claim 10

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said valve means comprising a thermo-modulated fluid pressure-regulating valve comprising: a valve body defining a valve cavity including first and second cavity portions separated from one another and having separate fluid inlets and outlets, a primary valve member movable within said first cavity portion for controlling primary fluid flow through said first cavity portion, pressure-sensitive control means for controlling the position of said primary valve member in response to fluid pressure within said first cavity portion, a temperature-responsive, expansible thermal element within said second cavity portion, resilient means interconnecting said thermal element and said control means whereby said thermal element transmits a variable force to said control means for controlling the position of said primary valve member.

Claim 11

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, and system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said valve means comprising a thermo-modulated fluid pressure-regulating valve comprising: a valve body defining a valve cavity including first and second cavity portions separated from one another and having separate fluid inlets and outlets, a primary valve member movable within said first cavity portion for controlling primary fluid flow through said first cavity portion, pressure-sensitive control means for controlling the position of said primary valve member in response to fluid pressure within said first cavity portion, a temperature-responsive, expansible thermal element within said second cavity portion, resilient means interconnecting said thermal element and said control means whereby said thermal element transmits a variable force to said control means for controlling the position of said primary valve member.

Claim 12

A system according to claim 6 wherein said hydraulic fan motor is in a hydraulic circuit having a pump means, said pump means supplying pressure fluid to said hydraulic fan motor, said thermo-modulated pressure relief valve being connected in parallel with said fan motor, first passage means directing said pressure fluid through said second cavity portion whereby said thermal element senses the temperature of said fluid, and second passage means directing pressure fluid from the intake side of said fan motor into the inlet of said first cavity portion and from the outlet of said first cavity portion to the discharge side of said fan motor.

Claim 13

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said hydraulic motor and valve means being in a hydraulic circuit including a pump means for delivering pressure fluid to said motor, said hydraulic circuit including a variable resistance downstream from and in series with said hydraulic motor.

Claim 14

In a cooling system, a speed control for a hydraulic motor driving a cooling fan comprising: valve means for controlling fluid pressure at the inlet side of said motor, motor inlet pressure-sensing means including passage means interconnecting the inlet side of said motor and said valve means in a manner such that inlet fluid pressure acts on said valve means in a direction tending to reduce said inlet pressure, means for applying a variable pressure to said valve means in a direction tending to increase said motor inlet pressure, system temperature-sensing means operable to vary the pressure exerted on said valve means by said pressure-applying means in response to variations in system temperature, said hydraulic motor and valve means being in a hydraulic circuit including a pump means for delivering pressure fluid to said motor, said hydraulic circuit including a variable resistance downstream from and in series with said hydraulic motor.

Claim 15

A system according to claim 2 wherein said hydraulic motor is in an open center hydraulic circuit.

Claim 16

A system according to claim 2 wherein said hydraulic motor is in a closed center hydraulic circuit.

Claim 17

A system according to claim 2 wherein said hydraulic motor is in a hydraulic circuit having a variable resistance connected in series with said motor downstream thereof.

Claim 18

A system according to claim 2 wherein said hydraulic motor is a fixed displacement motor and is in a hydraulic circuit having a fixed displacement pump delivering pressure fluid to said motor.

Claim 19

A system according to claim 2 wherein said motor is a fixed displacement motor in a hydraulic circuit having a variable displacement pump delivering pressure fluid to said motor.

Claim 20

A system according to claim 2 wherein said motor is a fixed displacement motor in a hydraulic circuit including a fixed displacement pump, said pressure-regulating means being connected in parallel with said motor and connected in series with said pump, said hydraulic circuit including a variable resistance downstream of said pressure-regulating means and said motor.

Claim 21

A system according to claim 2 wherein said hydraulic motor is in a hydraulic circuit including a variable displacement pump means, and said pressure-regulating means includes a valve means in series with said motor and said pump means.

Claim 22

A system according to claim 2 wherein said hydraulic motor is in a hydraulic circuit having a variable displacement pump means for delivering pressure fluid to said motor and a variable resistance, said pressure-regulating means being connected in series with said motor and in parallel with said variable resistance.

Claim 23

A system according to claim 16 wherein said variable displacement pump means includes variable pressure compensator means operable to provide a predetermined low pump discharge pressure when only said hydraulic motor is operating and to provide a predetermined higher pump discharge pressure when said variable resistance means is operating.

Claim 24

A system according to claim 2 wherein said hydraulic motor is in a hydraulic circuit including a variable displacement pump means for delivering pressure fluid to said motor, said hydraulic circuit including a variable resistance, said variable resistance being connected in series with said pressure-regulating means and said motor downstream of said motor.

Claim 25

A system according to claim 2 wherein said hydraulic motor is in a hydraulic circuit including a variable discharge pump, said differential pressure across said motor being controlled by said pressure-regulating means in a manner so as to be unaffected by changes, if any, in the flow discharge of said pump and in the discharge pressure of said pump throughout at least a major intermediate portion of the flow discharge range and discharge pressure range of said pump.

Claim 26

A cooling system including a hydraulic circuit comprising: a cooling fan, a fluid motor for rotating said fan, a variable displacement pump for driving said motor, and valve means connected in series with said fluid motor for controlling the pressure differential across said motor, said valve means being directly responsive to changes in differential pressure across said motor and to changes in temperature of the system to be cooled in a manner such that the pressure differential across said motor changes in response to changes in said temperature and independently of fluctuations in the output pressure of said pump.

Claim 27

A cooling system including a hydraulic circuit comprising: a cooling fan, a fluid motor for rotating said fan, a variable displacement pump for driving said motor, and valve means connected in series with said fluid motor for controlling the pressure differential across said motor, said valve means being directly responsive to changes in differential pressure across said motor and to changes in temperature of the system to be cooled in a manner such that the pressure differential across said motor changes in response to changes in said temperature and independently of fluctuations in the output pressure of said pump.

Claim 28

A system according to claim 20 wherein said pump is pressure-compensated to deliver a predetermined output pressure at variable flow.

Claim 29

A system according to claim 20 including a second fluid motor means driven by said pump.

Claim 30

A system according to claim 20 including a second fluid motor driven by said pump, said second motor being connected in parallel with said fan motor and said valve means.

Claim 31

A system according to claim 23 wherein said pump is compensated to deliver variable predetermined output pressures at variable flow rates.

Claim 32

A system according to claim 6 wherein said control means includes a pilot valve means for controlling a pilot flow of fluid, said resilient means transmitting a variable force to said pilot valve means to affect said pilot flow, said primary valve member including means responsive to changes in said pilot flow for changing the positioning of said primary valve member and thereby controlling said primary flow.