Back pressure relief motor control for a non-bleeder turbine style hvlp spray gun

A high volume low pressure (HVLP) turbine assembly, comprising:

• a turbine assembly housing;
• a turbine disposed within the housing, the turbine comprising a turbine fan rotatable within a turbine casing, the turbine casing comprising a turbine air inlet and a turbine air outlet;
• a hose outlet fitting connected to the housing, the hose outlet fitting in airflow communication with the turbine air outlet, where the hose outlet fitting is configured to be connectable to an air hose for a spray gun;
• an electric motor mechanically coupled to the turbine fan and configured to rotate the turbine fan inside the turbine casing;
• a microcontroller disposed within the housing, where the microcontroller is electrically connected to the electric motor and wherein the microcontroller comprises a proportional-integral-derivative loop controlling the electric motor configured to maintain a constant output pressure under a variable demand load;
• a temperature sensor attached to the turbine casing, the temperature sensor electrically connected to the microcontroller, wherein the microcontroller is configured to turn off the electric motor if the temperature sensor senses an operating temperature above a predefined temperature threshold;
• a power input electrically coupled to the microcontroller;
• a pressure sensor in airflow communication with the turbine air outlet, where the pressure sensor is electrically connected to the microcontroller;
• an airflow sensing means electrically connected to the microcontroller, and wherein the airflow sensing means comprises monitoring an error term of the proportional-integral-derivative loop, wherein a period of inactivity is indicated by the error term settling to substantially zero;
• a timer electrically connected to the microcontroller;
• wherein the microcontroller is configured to reduce the speed of the electric motor to an idle speed after a predetermined time has elapsed, wherein the predetermined time is started when the airflow sensing means indicates the period of inactivity;
• and
• wherein the microcontroller is configured to increase the speed of the electric motor from the idle speed when an abrupt change in the error term of the proportional-integral-derivative loop is detected.

A high volume low pressure (HVLP) turbine assembly, comprising:

• a turbine comprising a turbine fan rotatable within a turbine casing, the turbine casing comprising a turbine air inlet and a turbine air outlet, wherein the turbine air outlet comprises a hose outlet fitting where the hose outlet fitting is configured to be connectable to an air hose for a spray gun;
• an electric motor mechanically coupled to the turbine fan and configured to rotate the turbine fan inside the turbine casing;
• a microcontroller electrically connected to the electric motor and configured to control a speed of the electric motor;
• a power input electrically coupled to the microcontroller;
• a pressure sensor in airflow communication with the turbine air outlet, where the pressure sensor is electrically connected to the microcontroller;
• an airflow sensing means electrically connected to the microcontroller;
• a timer electrically connected to the microcontroller;
• wherein the microcontroller is configured to reduce the speed of the electric motor to an idle speed after a predetermined time has elapsed, wherein the predetermined time is started when the airflow sensing means indicates a period of inactivity;
• wherein the microcontroller comprises a proportional-integral-derivative loop controlling the electric motor configured to maintain a constant output pressure under a variable demand load;
• and
• wherein the airflow sensing means comprises monitoring an error term of a proportional-integral-derivative loop of the microcontroller, wherein the period of inactivity is indicated by the error term settling to substantially zero.