An external cooling system for hydraulic fluid of an aircraft hydraulic system. The external cooling system includes a heat exchanger, where an input side of the heat exchanger is connected to a hydraulic fluid reservoir of the aircraft hydraulic system and an output side of the heat exchanger is connected to suction ports of a return side of an electric motor driven pump (EMDP) of the aircraft hydraulic system. The external cooling system operates on 120 VAC power and the hydraulic fluid does not exceed a maximum pressure of 50 pounds per square inch gauge. The EMDP pumps hydraulic fluid through the hydraulic system under conditions wherein fuel tanks in the aircraft are empty, and the external cooling system cools the hydraulic fluid as the EMDP pumps the hydraulic fluid, wherein the hydraulic fluid passes from the hydraulic fluid reservoir and through the external cooling system before entering the EMDP.

In accordance with an example embodiment, a hydraulic system may include a pump, reservoir, accumulator, hydraulic cylinder, ride control valve assembly, and controller. The ride control valve assembly may include a charging valve, discharging valve, and a head ride control valve. The controller may open the head ride control valve when a ride control feature has been activated, or open the charging valve if the ride control feature has not been activated and a hydraulic fluid warmup is to be performed.

Provided are embodiments for a system including an adaptive controller, wherein the system includes a hydraulic actuator including a fluid medium, and a sensor that is disposed on the hydraulic actuator, wherein the sensor is configured to obtain sensor data of the actuator. The system also includes a processor configured to calculate an ultrasonic velocity in the fluid medium using the sensor data, wherein the processor is further configured to determine a temperature of the fluid medium based at least in part on the calculated velocity, and a controller coupled to the actuator, wherein the controller is configured to control the actuator based at least in part on the calculated velocity and determined temperature. Also provided are embodiments for a method for operating the adaptive controller.

A distributor (3) of the closed-center, load sensing type, connected to a variable displacement pump (1) comprises a valve device (10, 110), composed of a logic element, which is pilot-operated and configured to bring a high-pressure channel (2) into communication with a low-pressure channel (4), the connection being usually opened by the combined action of an equivalent pressure generated by an elastic member (12) and a counter-pressure which is generated, under operative conditions, in the low-pressure channel (4). The connection is closed in a switching position and it is pilot-operated to a closure position by the combined action of a high-pressure signal (P) and a load sensing signal (LS).

It is an object of the present invention to provide a construction machine having a good engine starting property in a low temperature environment.

The construction machine of the present invention includes: an electric pump having a delivery port connected to a line part of a pilot line, the line part connecting a pilot pump with a pilot control valve; a motor that drives the electric pump; and a temperature sensor that measures a temperature of a hydraulic working fluid delivered from the pilot pump. A controller starts driving of the motor in the case where a key switch is operated from a key OFF state to a key ON state and where the temperature of the hydraulic working fluid measured by the temperature sensor is lower than a predetermined temperature.

A hydraulic propulsion system converts heat or thermal energy into hydraulic energy, and such hydraulic energy into mechanical work. The hydraulic propulsion system includes a thermal unit, a hydraulic cylinder with pistons and springs mounted therein, one or more hydraulic motors, one or more hydraulic accumulators, and one or more electrical energy generators, as well as a plurality of flow control valves to control the flow of hydraulic fluid between the various components. The hydraulic propulsion system may be enhanced by an energy transmission unit including a wave generator.

A valve includes a valve housing (2) for transport of a heatable fluid such as hydraulic oil. The valve housing has at least one utility connection (A, B), at least one pressure supply connection (P), and at least one return connection (T1, T2). A control slide (6) is guided in the valve housing (2) in a longitudinally displaceable manner. In at least one position of the control slide (6), the pressure supply connection (P) is at least partially separated from the utility connection (A, B), and the heatable fluid arrives, proceeding from this pressure supply connection (P) and via a heat-emitting connection in the control slide (6), at the at least one return connection (TI, T2) as a loss volume flow. The loss volume flow serves as a heat source and heats at least regions of the control slide (6).

Provided are embodiments for a system including an adaptive controller, wherein the system includes a hydraulic actuator including a fluid medium, and a sensor that is disposed on the hydraulic actuator, wherein the sensor is configured to obtain sensor data of the actuator. The system also includes a processor configured to calculate an ultrasonic velocity in the fluid medium using the sensor data, wherein the processor is further configured to determine a temperature of the fluid medium based at least in part on the calculated velocity, and a controller coupled to the actuator, wherein the controller is configured to control the actuator based at least in part on the calculated velocity and determined temperature. Also provided are embodiments for a method for operating the adaptive controller.

Disclosed embodiments include power machines, and hydraulic systems for power machines, in which a machine controller is configured to detect high temperature conditions of the hydraulic oil and to responsively control or reduce the overall torque available from the engine to reduce heat generation in the hydraulic system.

A work machine is provided. The work machine includes a changeover valve capable of disabling area limiting control by bypassing an area limiting control solenoid proportional valve disposed in a pilot line through which pilot pressure generated by a hydraulic pilot type operation device is guided to a directional control valve and the work machine can perform the area limiting control while ensuring response of a work implement. When a first fluid temperature T1 is higher than a first predetermined temperature Ta and a control changeover switch 66 specifies disabling of the area limiting control, a controller brings a plurality of changeover valves into a bypass position. When the first fluid temperature T1 is equal to or lower than the first predetermined temperature Ta, the controller brings the changeover valves into a communication position and places the solenoid proportional valves in a fully open position.