SYSTEM AND METHOD FOR MONITORING CONTROL STATUS OF AN EXHAUST APPARATUS PRESSURE CONTROL SYSTEM
An exhaust pressure control apparatus is disclosed. The exhaust pressure control apparatus including a main body in which an inlet port and an outlet port are formed, the main body also including a pilot chamber. The system also includes a spool comprising an upper slide and a lower slide, the upper slide forming a movable portion of the pilot chamber, and the spool is held by the upper slide and the lower slide so that it can slide in an axial direction over a sliding surface connecting the intake port and the discharge port. A control system regulates a pressure in the intake port by controlling a pressure regulating gas supplied to the pilot chamber, and a control status portion provides an indication of the stability of the control system based upon the pressure in the pilot chamber.
1 . An exhaust pressure control apparatus comprising:
a main body in which an inlet port and an outlet port are formed, the main body also including a pilot chamber;
a spool comprising an upper slide and a lower slide, the upper slide forming a movable portion of the pilot chamber, and the spool is held by the upper slide and the lower slide so that it can slide in an axial direction over a sliding surface connecting the intake port and the discharge port;
a control system to regulate a pressure in the intake port by controlling a pressure regulating gas supplied to the pilot chamber; and
a control status portion configured to provide an indication of the stability of the control system based upon the pressure in the pilot chamber.
2 . The exhaust apparatus pressure control apparatus of claim 1 , wherein the control status portion includes a differential pressure sensor arranged so as to provide the indication of the stability of the control system based upon a difference between the pressure in the pilot chamber and a pressure in the intake port.
3 . The exhaust apparatus pressure control apparatus of claim 2 , wherein the differential pressure sensor is coupled to the intake port and atmospheric pressure, and responsive to a control-status query, a control circuit sends switching signals to uncouple the differential pressure sensor from atmospheric pressure and couple the differential pressure sensor to the pilot chamber.
4 . The exhaust apparatus pressure control apparatus according to claim 1 , wherein the control system includes:
an absolute pressure sensor; and
a control valve disposed to modulate a flow of the pressure regulating gas supplied to the pilot chamber, the control system driving the control valve based upon an output of the absolute pressure sensor.
5 . The exhaust apparatus pressure control apparatus according to claim 4 , wherein the control system includes a differential pressure sensor coupled to atmospheric pressure and the intake port, and the control system drives the control valve based on the output from the absolute pressure sensor or differential pressure sensor.
6 . The exhaust apparatus pressure control apparatus according to claim 5 , wherein the control status portion includes the differential pressure sensor, and responsive to a control-status query, a control circuit sends switching signals to uncouple the differential pressure sensor from atmospheric pressure and couple the differential pressure sensor to the pilot chamber.