High Ambient Temperature Propulsion Speed Control Of A Self-Propelled Agricultural Product Applicator

A system for limiting operating speed at high temperatures in a hydraulically-driven, self-propelled, agricultural product applicator having a hydraulic system including a pump supplying pressurized fluid to a variable-displacement hydraulic motor operatively connected for propelling the applicator, the system comprising:

• a temperature sensor operatively connected for detecting a temperature of the pressurized hydraulic fluid in the hydraulic system;
• and
• a propel controller operatively connected between the temperature sensor and the propulsion motor and configured for limiting displacement of the propulsion motor according to a predetermined de-rated condition resulting in reduced motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is, detected by the temperature sensor:
• wherein the propulsion motor includes a swashplate for controlling motor rotational speed as a function of swashplate angle, and the propel controller is operatively connected for limiting motor speed by limiting swashplate angle in the de-rated condition.

A system for limiting operating speed at high temperatures in a hydraulically-driven, self-propelled, agricultural product applicator having a hydraulic system including a pump supplying pressurized hydraulic fluid to a variable -displacement hydraulic motor operatively connected for propelling the applicator, the system comprising:

• a temperature sensor operatively connected for detecting a temperature of the pressurized hydraulic fluid in the hydraulic system;
• and
• a propel controller operatively connected between the temperature sensor and the propulsion motor arid configured for limiting displacement of the propulsion motor according to a predetermined de-rated condition resulting in reduced motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor:
• wherein the propel controller is further configured for maintaining the propulsion motor in the de-rated condition until the temperature sensor detects that the hydraulic fluid temperature has dropped to a predetermined motor de-rating de-activation temperature.

A self-propelled, hydraulically-driven, agricultural product applicator having an engine and a hydrostatic drive system, the hydrostatic drive system including a propulsion pump driven by the engine at a fixed ratio of engine speed and supplying pressurized hydraulic fluid to a variable-displacement hydraulic propulsion motor operatively connected for propelling the applicator, and a system for limiting operating speed of the hydraulically-driven, self-propelled, agricultural product applicator at high temperatures, where the system for limiting speed at high temperatures comprises:

• a temperature sensor operatively connected for detecting a temperature of the pressurized hydraulic fluid in the hydraulic system;
• and
• a propel controller operatively connected between the temperature sensor and the propulsion motor and configured for limiting displacement of the propulsion motor according to a predetermined de-rated condition resulting in reduced motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor;
• wherein the propel controller is further configured for maintaining the propulsion motor in the de-rated condition until the temperature sensor detects that the hydraulic fluid temperature has dropped to a predetermined motor de-rating de-activation temperature.

A method for limiting operating speed at high temperatures in a hydraulically-driven, self-propelled, agricultural product applicator having a hydraulic system including a propulsion pump supplying pressurized hydraulic fluid to a variable-displacement hydraulic propulsion motor operatively connected for propelling the applicator, the method comprising:

• operatively connecting a temperature sensor for detecting a temperature of the pressurized hydraulic fluid in the hydraulic system;
• operatively connecting a propel controller to the temperature sensor and the propulsion motor and configuring the controller for limiting displacement of the propulsion motor according to a predetermined de-rated condition resulting in reduced motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor;
• and
• limiting displacement of the propulsion motor according to the predetermined de-rated condition resulting in reduced propulsion motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor.

A method for limiting operating speed at high temperatures in a hydraulically-driven, self-propelled, agricultural product applicator having a hydraulic system including a propulsion pump supplying pressurized hydraulic fluid to a variable-displacement hydraulic propulsion motor operatively connected for propelling the applicator, the method comprising:

• operatively connecting a temperature sensor for detecting a temperature of the pressurized hydraulic fluid in the hydraulic, system:
• operatively connecting a propel controller between the temperature sensor and the propulsion motor and configuring the controller for limiting displacement of the propulsion motor according to a predetermined de-rated condition resulting in reduced motor speed, when a predetermined motor tie-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor;
• and
• limiting displacement of the propulsion motor according to the predetermined de-rated condition resulting in reduced propulsion motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor;
• wherein:
• the propulsion motor includes a swashplate for controlling motor rotational speed as a function of swashplate angle, and the propel controller is operatively connected for limiting propulsion motor speed by limiting swashplate angle in the de-rated condition;
• the propulsion motor operates at maximum speed when the swashplate angle and corresponding motor displacement arc at minimum values, and the controller is operatively connected to control the swashplate angle at an angle greater than the minimum value of swashplate angle in the de-rated condition, to thereby limit operation of the propulsion motor to a speed less than the maximum speed of the motor whenever the controller is limiting the motor to operation in the de-rated condition;
• and
• the method further includes, controlling the swashplate angle at an angle greater than the minimum value of swashplate angle in the de-rated condition, to thereby limit operation of the propulsion motor to a speed less than the maximum speed of the motor whenever the controller is limiting the motor to operation in the de-rated condition.

A method for limiting operating speed at high temperatures in a hydraulically-driven, self-propelled, agricultural product applicator having a hydraulic system including a propulsion pump supplying pressurized hydraulic fluid to a variable-displacement hydraulic propulsion motor operatively connected for propelling the applicator, the method comprising:

• operatively connecting a temperature sensor for detecting a temperature of the pressurized hydraulic fluid in the hydraulic system;
• operatively connecting a propel controller between the temperature sensor and the propulsion motor and configuring the controller for limiting displacement of the propulsion motor according to a predetermined de-rated condition resulting in reduced motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor;
• and
• limiting displacement of the propulsion motor according to the predetermined de-rated condition resulting in reduced propulsion motor speed, when a predetermined motor de-rating activation temperature limit of the hydraulic fluid is detected by the temperature sensor;
• wherein the controller is configured for providing and maintaining a warning signal, and for reducing and maintaining propulsion motor displacement in accordance with a schedule of predetermined temperatures as determined by the temperature sensor, the method further comprises performing at least one operation from the list of operations consisting of:
• sending the warning signal at a warning activation temperature, and maintaining the warning until the temperature sensor detects that the hydraulic fluid has cooled to a warning de-activation temperature that is lower than the warning activation temperature;
• limiting motor displacement to a first de-rated condition in a manner providing a first reduction in operating speed of the applicator at a first motor de-rating activation temperature that is higher than the warning activation) temperature, and maintaining the limited motor displacement in the first derated condition until the temperature sensor detects that the hydraulic fluid has cooled to a first motor de-rating de-activation temperature that is lower than the first motor de-rating activation temperature;
• and
• limiting motor displacement to a second derated condition in a manner providing a second reduction in operating speed of the applicator at a second motor de-rating activation temperature that is higher than the first motor derating activation temperature, and maintaining the limited motor displacement in the second de-rated condition until the temperature sensor detects that the hydraulic fluid has cooled to a second motor derating de-activation temperature that is lower than the second motor de-rating activation temperature.