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US 7,920,949 B2Granted
Feedback adjustment for open-loop torque control map
AssigneeCaterpillar Inc.
InventorsBrian D Kuras, Frank A DeMarco, Adam J Vaccari, Tyler Bowan
Life of this patent
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Abstract
A variator torque control system and method utilize a hydraulic actuator to control the variator output via a torque control map, wherein the values of the torque control map are evaluated and modified during use of the map to improve map accuracy. In an example, errors in the map are evaluated to determine whether a system fault has occurred.
Claims20
A method of controlling an output torque of a variator having a hydraulic actuator responsive to an actuator pressure signal, the method comprising:
- receiving an indication of a first expected output torque;
- evaluating a plurality of parameters related to operation of the variator;
- reading a map to link the plurality of parameters to a first mapped value for the actuator pressure signal, wherein the first expected output torque is associated with the first mapped value;
- applying the first mapped value to the hydraulic actuator as the actuator pressure signal;
- measuring a first output torque of the variator and comparing the first output torque to the first expected output torque to derive an error value;
- determining whether the error value conforms to at least one modification condition;
- replacing the first mapped value of the map with a modified value if it is determined that the error value conforms to at least one modification condition;
- determining whether the error value exceeds a first error limit value, and producing a system error signal if it is determined that the error value exceeds the first error limit value;
- and
- determining whether the error value has exceeded a second error limit value that is less than the first error limit value, and if so, whether the error value has exceeded the second error limit value more than a predetermined number of times, and producing the system error signal if the error value has exceeded the second error limit value more than the predetermined number of times.
7 more elements
A method of detecting a fault in a variator having a hydraulic actuator responsive to an actuator pressure signal, the method comprising:
- receiving an indication of a first expected output torque;
- evaluating a plurality of parameters related to operation of the variator;
- reading a map to link the plurality of parameters to a first mapped value for the actuator pressure signal, wherein the first expected output torque is associated with the first mapped value;
- applying the first mapped value to the hydraulic actuator as the actuator pressure signal;
- measuring a first output torque of the variator and comparing the first output torque to the first expected output torque to derive an error value;
- determining whether the error value exceeds a first error limit value;
- producing a system error signal if it is determined that the error value exceeds the first error limit value and otherwise determining whether the error value exceeds a second error limit value that is less than the first error limit value;
- determining whether the error value has exceeded the second error limit value more than a predetermined number of times if it is determined that the error value exceeds the second error limit value;
- and
- producing the system error signal if it is determined that the error value has exceeded the second error limit value more than the predetermined number of times.
7 more elements
A variator controller for controlling an output torque of a variator via a hydraulic actuator, the variator controller comprising:
- a processor system including:
- a digital data processor;
- a first data input connected to at least one circuit pressure sensor to receive a signal related to a hydraulic pressure within an internal hydraulic circuit of the variator;
- a second data input connected to a pump speed sensor to receive a signal related to a rotational speed of a variator input shaft;
- a third data input connected to a motor speed sensor to receive a signal related to a rotational speed of a variator output shaft;
- a fourth data input connected to an operator interface to receive a signal related to an expected torque;
- a fifth data input connected to receive a signal corresponding to a first mapped control pressure based on data received at the first, second, and third data inputs;
- and
- a computer-readable memory having stored thereon computer-executable instructions to cause the processor to evaluate a plurality of parameters related to operation of the variator, read a map to link the plurality of parameters to a first mapped value associated with the first expected torque, and determine that the error value conforms to at least one modification condition and replace the first mapped value with a modified value.
6 more elements
Dependencies are inferred from the claim text.