Low ripple gear pump/motor

Abstract

A gear pump system comprises a gear pump having an inlet, an outlet, and at least one rotating gear for pumping fluid from the inlet to the outlet and producing an output flow characterized by pressure pulses arising from the geometry of the teeth of the gear; and at least one valve operative to vary the output flow in timed relation to the rotation of the gear for counteracting the pressure pulses, thereby to reduce the amplitude of the pressure pulses.

1 . A gear pump system comprising a gear pump having an inlet, an outlet, and at least one rotating gear for pumping fluid from the inlet to the outlet and producing an output flow characterized by pressure pulses arising from the geometry of the teeth of the gear; and at least one valve operative to vary the output flow in timed relation to the rotation of the gear for counteracting the pressure pulses, thereby to reduce the amplitude of the pressure pulses.  
   
   
       2 . A system as set forth in  claim 1 , wherein the valve is operative to introduce secondary pulses of flow in timed relation to the pressure pulses to counteract the pressure pulses.  
   
   
       3 . A system as set forth in  claim 1 , wherein the valve includes a pulse width modulated valve.  
   
   
       4 . A system as set forth in  claim 1 , comprising a sensor for providing an output synchronous with the pressure pulses, and a controller for controlling the at least one valve to introduce into the flow passage secondary pulses of flow “phased” with the pressure pulses.  
   
   
       5 . A system as set forth in  claim 1 , wherein the sensor includes a position sensor operatively coupled to the at least one rotating gear to provide a position output signal representative of the position of the at least one gear.  
   
   
       6 . A system as set forth in  claim 4 , wherein the valve is a pulse width modulated valve, and the controller controls the modulation of the valve in timed relation to the position output of the position sensor.  
   
   
       7 . A system as set forth in  claim 4 , wherein the sensor includes a pressure sensor for sensing the pressure at the outlet of the pump.  
   
   
       8 . A system as set forth in  claim 1 , wherein the at least one valve is operated to modulate flow at a rate at least equal the rate of pressure pulses.  
   
   
       9 . A system for counteracting pressure pulses in a fluid circuit comprising a fluid circuit characterized by pressure pulses, and a flow control device for varying the flow in the fluid circuit in a manner that counteracts the pressure pulses, thereby to reduce the amplitude of the pressure pulses.  
   
   
       10 . A system as set forth in  claim 9 , wherein the flow control device includes at least one valve operative to open and close in timed relation to the pressure pulses for controlling flow of fluid to or from the fluid circuit.  
   
   
       11 . A system as set forth in  claim 10 , wherein the valve is operative under the control of the controller to introduce into the fluid circuit secondary pulses of flow “phased” with the pressure pulses.  
   
   
       12 . A system as set forth in  claim 10 , wherein the valve includes a pulse width modulated valve.  
   
   
       13 . A system as set forth in  claim 10 , wherein the fluid circuit includes a pump, and the pressure pulses are produced by the pumping action of the pump.  
   
   
       14 . A system as set forth in  claim 13 , wherein the at least one valve is mechanically connected to a rotating component of the pump.  
   
   
       15 . A system as set forth in  claim 13 , wherein the timing of the at least one valve is electronically controlled.  
   
   
       16 . A method for counteracting pressure pulses in a fluid circuit comprising the steps of using a sensor to provide an output synchronous with the pressure pulses, and operating a valve to vary the flow in the fluid circuit a function of the output of the sensor so as to vary the flow in fluid circuit in a manner that counteracts the pressure pulses, thereby to reduce the amplitude of the pressure pulses.  
   
   
       17 . A motor system comprising a hydraulic gear motor having an inlet for receiving an input flow of pressurized fluid, an outlet, and at least one rotating gear rotated by flow of fluid from the inlet to the outlet and producing an output torque characterized by torque pulses arising from the geometry of the teeth of the gear; and at least one valve operative to vary the input flow pressure in timed relation to the rotation of the gear for counteracting the torque pulses, thereby to reduce the amplitude of the torque pulses.