Electric Pump

Abstract

A pump for pumping liquid has an electric motor driving an impeller disposed within a pump chamber. The motor has a stator, a rotor, and an end cap. The end cap has a printed circuit board upon which are mounted two brushes connected to a pair of motor terminals through a thermistor. Optionally, the motor may include, singularly or in combination, one or more inductors located between the brushes and the motor terminals, a varistor for preventing excessive voltage spikes electrically connected between the motor terminals, and one or more capacitors electrically connecting the motor terminals to ground.

1 . An electric pump for pumping liquid, comprising:
 a pump housing defining a pump chamber;   an impeller disposed in the pump chamber; and   an electric motor for driving the impeller, the motor comprising:
 a stator defining a plurality of magnetic poles; and 
   a rotor configured to rotate relative to the stator, the rotor comprising: a shaft; a rotor core fixed to the shaft; a commutator fixed to the shaft adjacent one end of the rotor core; and a plurality of winding coils wrapped around the rotor core and electrically connected to the commutator;   first and second motor terminals configured to be connected to an external power source;   first and second brushes in sliding contact with the commutator; and   a positive temperature coefficient thermistor,   wherein the first brush is electrically connected to the first motor terminal through the thermistor; and   the second brush is electrically connected to the second motor terminal.   
     
     
         2 . The pump of  claim 1 , wherein the brushes, the thermistor, and the motor terminals are mounted on an end cap located on an axial end of the motor. 
     
     
         3 . The pump of  claim 2 , wherein the brushes and the thermistor are mounted on a printed circuit board mounted on the end cap of the motor. 
     
     
         4 . The pump of  claim 1 , further comprising one or more inductors, electrically connected between the brushes and the motor terminals, respectively. 
     
     
         5 . The pump of  claim 4 , wherein the one or more inductors comprise a first inductor and a second inductor, such that the first brush is connected to the thermistor through the first inductor, and the second brush is connected to the second motor terminal through the second inductor. 
     
     
         6 . The pump of  claim 1 , further comprising a varistor, wherein the varistor is connected to the two motor terminals in series with the thermistor. 
     
     
         7 . The pump of  claim 1 , further comprising a first capacitor and a second capacitor, wherein the first capacitor connects a terminal of the thermistor not connected to the first motor terminal to ground, and the second capacitor connects the second motor terminal to ground. 
     
     
         8 . The pump of  claim 7 , wherein the capacitors are connected to a ground terminal that is connected to a motor housing of the motor. 
     
     
         9 . The pump of  claim 1 , wherein the pump is configured to pump water or a detergent solution onto an automobile windshield. 
     
     
         10 . The pump of  claim 1 , further comprising a pump cover incorporating a connector housing accommodating the motor terminals, with a first end of the motor terminals disposed in the connector for connection to a power supply and a second end of the motor terminals being inserted in respective sockets disposed on the end cap.