Machine control system having hydraulic warmup procedure

A machine control system, comprising:

• a pump driven to pressurize fluid;
• a low pressure reservoir;
• at least one actuator connected to receive fluid pressurized by the pump and discharge fluid to the low pressure reservoir;
• a bypass passage situated to allow fluid pressurized by the pump to bypass the at least one actuator and flow to the low pressure reservoir;
• a warmup valve disposed within the bypass passage and being movable between a flow-passing position and a flow-blocking position;
• a hydraulic temperature sensor configured to generate a signal indicative of a temperature of the fluid;
• and
• a controller in communication with the pump, the warmup valve, and the hydraulic temperature sensor, the controller being configured to:
• move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust an input speed of the pump in response to the signal;
• fix the displacement of the pump at a maximum displacement position when the signal indicates a temperature of the fluid less than a desired temperature;
• set the input speed of the pump to a speed greater than a low-idle speed when the signal indicates the temperature of the fluid less than the desired temperature;
• and
• increment the input speed of the pump over a period of time when the signal indicates the temperature of the fluid less than the desired temperature.

A method of warming a machine control system, comprising:

• displacing an amount of fluid at a displacement rate to pressurize the fluid;
• directing pressurized fluid to an actuator;
• sensing a temperature of the fluid;
• in response to the sensed temperature, selectively directing pressurized fluid to bypass the actuator, fixing the displacement amount, and adjusting the displacement rate,
• the displacement amount being fixed, the pressurized fluid being directed to bypass the actuator, and the displacement rate being periodically incremented from a low-idle rate when the sensed temperature is less than about 30° C.,
• incrementing the displacement rate to a maximum rate and maintaining the displacement rate at the maximum rate for a period of time when the sensed temperature is less than about 30° C.;
• and
• returning the displacement rate to a low-idle rate, reducing the displacement amount to a minimum amount, and blocking the pressurized fluid from bypassing the actuator when the temperature of the fluid increases above about 30° C. or the displacement rate has been maintained at the maximum rate for the period of time.

A method of warming a machine control system, comprising:

• displacing an amount of fluid at a displacement rate to pressurize the fluid;
• directing pressurized fluid to an actuator;
• driving the displacing of fluid with an engine;
• sensing a temperature of the engine,
• sensing a temperature of the fluid;
• and
• in response to the sensed fluid temperature, selectively directing pressurized fluid to bypass the actuator, fixing the displacement amount, and adjusting the displacement rate only after a temperature of the engine has increased to a desired engine temperature or the engine has driven the displacing of fluid for a period of time.

A machine, comprising:

• an engine;
• an engine temperature sensor configured to generate an engine temperature signal indicative of a temperature of the engine;
• a pump driven by the engine to pressurize fluid;
• a low pressure reservoir;
• a work tool;
• at least one actuator connected to receive fluid pressurized by the pump and discharge fluid to the low pressure reservoir to move the work tool;
• a valve stack having:
• a supply passage fluidly connected to the pump;
• a drain passage fluidly connected to the drain passage;
• at least one control valve fluidly connected between the supply and the drain passages and being configured to selectively regulate fluid flow to and from the at least one actuator;
• a bypass passage fluidly connecting the supply and drain passages;
• and
• a warmup valve disposed within the bypass passage and being movable between a flow-passing position and a flow-blocking position;
• a hydraulic temperature sensor configured to generate a hydraulic temperature signal indicative of a temperature of the fluid;
• and
• a controller in communication with the engine, the engine temperature sensor, the pump, the warmup valve, and the hydraulic temperature sensor, the controller being configured to move the warmup valve to the flow-passing position, fix a displacement position of the pump, and adjust periodically increment a speed of the engine in response to the hydraulic temperature signal only after the engine temperature signal indicates a temperature of the engine above a desired engine temperature or the engine has operated for a period of time.