Multiple piston pump control
First Claim
1. A method of reducing pulsations in the flow produced by a multiple piston assembly pump of the kind which has a pressure piston assembly and a damper piston assembly connected in series with the outlet of the pressure piston assembly connected to the inlet of the damper piston assembly and which provides an overlap between the flow output of the piston assemblies during a portion of the strokes of the piston assemblies and wherein a sudden pump speed change occurs during the overlap between the flow output of the piston assemblies, said method comprising,controlling, except during the overlap, the speed of the pump by a first fast control loop which responds to pump output pressure and a second slow control loop which responds to average pump speed,detecting the sudden pump speed change which occurs during the overlap between the flow output of the piston assemblies, said step of detecting the speed change including detecting the beginning and the end of the actual duration of the time period of the overlap, anddeactivating the slow control loop from controlling the pump speed during the time period of the overlap and running the pump to hold a substantially constant pump output pressure during the duration of the time period until the pump speed returns to the normal speed existing prior to the sudden speed change.
5 Assignments
0 Petitions
Accused Products
Abstract
A multiple piston assembly pump of the kind which provides an overlap between the flow output of the piston assemblies during a portion of the strokes of the piston assemblies incorporates a method and apparatus for reducing pulsations in the flow during the time when the pump is changing over from one piston pumping to the other piston pumping. A first fast control loop responds to pump output pressure and is operatively associated with a second slow control loop which responds to average pump speed. A sudden pump speed change is detected, and the pump is run in a constant pressure mode until the speed returns to normal.
32 Citations
4 Claims
-
1. A method of reducing pulsations in the flow produced by a multiple piston assembly pump of the kind which has a pressure piston assembly and a damper piston assembly connected in series with the outlet of the pressure piston assembly connected to the inlet of the damper piston assembly and which provides an overlap between the flow output of the piston assemblies during a portion of the strokes of the piston assemblies and wherein a sudden pump speed change occurs during the overlap between the flow output of the piston assemblies, said method comprising,
controlling, except during the overlap, the speed of the pump by a first fast control loop which responds to pump output pressure and a second slow control loop which responds to average pump speed, detecting the sudden pump speed change which occurs during the overlap between the flow output of the piston assemblies, said step of detecting the speed change including detecting the beginning and the end of the actual duration of the time period of the overlap, and deactivating the slow control loop from controlling the pump speed during the time period of the overlap and running the pump to hold a substantially constant pump output pressure during the duration of the time period until the pump speed returns to the normal speed existing prior to the sudden speed change.
-
3. A pump control for reducing pulsations in the flow produced by a multiple piston assembly pump of the kind which has a pressure piston assembly and a damper piston assembly connected in series with the outlet of the pressure piston assembly connected to the inlet of the damper piston assembly and which provides an overlap between the flow output of the piston assemblies during a portion of the strokes of the piston assemblies and wherein a sudden pump speed change occurs during the overlap between the flow output of the piston assemblies, said apparatus comprising,
first relatively fast responding control loop means for controlling the speed of the pump in response to pump output pressure, second relatively slow responding control loop means for controlling the speed of the pump in response to average pump speed, compensation means for detecting the sudden pump speed change, including detecting means for detecting the beginning and the end of the actual duration of the time period of the overlap, deactivating means for deactivating the relatively slow responding control loop means and for running the pump to hold a substantially constant pump output pressure during the duration of the time period until the pump speed returns to the normal speed existing prior to the sudden speed change.
Specification