Injection pump

Abstract

A chemical injection pump system includes a reversible and controllable electric motor driving a cam wheel having a pressure ramp and a suction ramp, which rotates about an axis; and at least injection pump having a reciprocating plunger which is actuated by rotation of the cam wheel. The motor may be an outrunner brushless DC motor having a rotor which acts as the cam wheel, with an outer surface defining a cam profile having a pressure ramp and a suction ramp, which rotates about a stator axis. The system may be controlled to independently operate two or more injection pumps at different injection rates.

1 . A pump system comprising:
 (a) an outrunner brushless DC motor comprising a stator and a rotor wherein the rotor has an outer surface defining a cam profile having a pressure ramp and a suction ramp, which rotates about the stator axis; and   (b) at least one pump head comprising an injection pump having a reciprocating plunger which is actuated by rotation of the cam profile.   
     
     
         2 . The pump system of  claim 1  wherein the outer cam profile is created by a non-circular profile of the rotor. 
     
     
         3 . The pump system of  claim 1  wherein the rotor has a circular profile but has an offset axis of rotation. 
     
     
         4 . The pump system of  claim 1  comprising at least two pump heads, radially arrayed around the rotor. 
     
     
         5 . The pump system of  claim 1 , further comprising a motor controller for controlling the speed and/or direction of the motor. 
     
     
         6 . The pump system of  claim 5  wherein the motor controller is configured to stroke at least one pump head by cycling the rotor backwards and forwards, over the entire pressure ramp, or a portion of the pressure ramp. 
     
     
         7 . The pump system of  claim 4  further comprising a motor controller for controlling the speed and/or direction of the motor and wherein the motor controller is configured to stroke one pump head by cycling the rotor backwards and forwards, over the entire pressure ramp, or a portion of the pressure ramp, while the other pump head is not actuated, or actuated at a lower injection rate. 
     
     
         8 . The system of  claim 1  wherein the pressure ramp comprises about 180 degrees of rotation of the rotor. 
     
     
         9 . The system of  claim 8  wherein the portion of the rotor which is not the pressure ramp comprises a base circle. 
     
     
         10 . A pump system comprising:
 (a) a reversible and controllable electric motor driving a cam wheel having a pressure ramp and a suction ramp, which rotates about an axis; and   (b) at least one pump head comprising an injection pump having a reciprocating plunger which is actuated by rotation of the cam wheel.   
     
     
         11 . The pump system of  claim 10  wherein the reversible and controllable motor comprises an outrunner BLDC, a stepper motor or a servo motor. 
     
     
         12 . The pump system of  claim 10  comprising two or more pump heads, and a cam wheel configured to operate a first pump head out of phase with another pump head. 
     
     
         13 . The pump system of  claim 12  wherein the two or more pump heads are arrayed at a 90 degree angle or an 180 degree angle from each other, and the cam wheel is circular with an offset axis of rotation. 
     
     
         14 . The pump system of  claim 12  comprising a motor controller configured to stroke one pump head by cycling the rotor backwards and forwards, over the entire pressure ramp, or a portion of the pressure ramp, while the other pump head is not actuated, or actuated at a lower injection rate. 
     
     
         15 . A method of actuating a reciprocating pump having a plunger, comprising the steps of
 (a) providing a reversible and controllable electric motor driving a cam wheel having a pressure ramp and a suction ramp, which rotates about an axis;   (b) rotating the cam wheel to actuate the plunger.   
     
     
         16 . The method of  claim 15  wherein the reversible and controllable motor comprises an outrunner BLDC, a stepper motor or a servo motor. 
     
     
         17 . The method of  claim 16  wherein the motor is an outrunner BLDC having a rotor which defines the cam wheel or which drives the cam wheel. 
     
     
         18 . The method of  claim 15  which actuates two or more reciprocating pumps, arrayed radially around the circumference of the cam wheel. 
     
     
         19 . The method of  claim 15  comprising the further step of cycling the motor backwards and forwards to stroke at least one pump on the pressure ramp. 
     
     
         20 . The method of  claim 19  wherein the motor is cycled backwards and forwards to stroke a first pump over the entire pressure ramp, or a portion of the pressure ramp, while a second pump is not actuated, or actuated at a lower injection rate. 
     
     
         21 . A chemical injection pump system comprising an injection pump having a suction valve and an output valve, the system comprising a mechanism configured to disable normal operation of one or both of the suction valve or the output valve, to reduce or eliminate fluid output of the pump. 
     
     
         22 . The system of  claim 21  wherein the mechanism is configured to maintain the suction valve in an open bypass position during a pressure stroke, to maintain the suction valve closed during a suction stroke, to maintain the output valve open during a suction stroke, and/or to maintain the output valve closed during a pressure stroke. 
     
     
         23 . The system of  claim 22  wherein the mechanism comprises a pin moveable between an extended position where it interferes with seating of the suction valve, and a non-interfering retracted position, and a ferromagnetic armature and a solenoid coil for actuating the pin. 
     
     
         24 . A method of disabling a chemical injection pump having a suction valve at its inlet and output valve at its outlet, comprising the step of disabling normal operation of either the suction valve or the output valve. 
     
     
         25 . The method of  claim 24  wherein normal operation is disabled by opening the suction valve during a pressure stroke of the pump while keeping the output valve closed.