Electro-mechanical drive mechanism for an impeller shroud of a variable water pump

Abstract

An external actuator for a variable water pump is provided having a housing and variable flow impeller located therein that is connected to a drive shaft. The actuator includes a housing and a drive ring rotatably mounted therein, with the drive ring having external teeth and an internal thread. A drive gear is engaged with the external teeth of the drive ring, with the drive gear being rotatably mounted in the housing. A drive nut having external threads is located within the drive ring with the external threads engaging the internal threads of the drive ring. Rotation of the drive ring causes an axial displacement of the drive nut. At least one actuator pin is connected to the drive nut and extends into the water pump housing to the variable flow impeller. A motor is connected to the drive gear for rotation of the drive gear to vary an output.

What is claimed is: 
     
         1 . An external actuator for a variable water pump which includes a housing and a variable flow impeller located in the housing that is connected to a drive shaft, the external actuator comprising:
 an actuator housing;   a drive ring rotatably mounted in the actuator housing, the drive ring having external teeth and an internal thread;   a drive gear engaged with the external teeth of the drive ring, the drive gear being rotatably mounted in the actuator housing;   a drive nut having external threads located within the drive ring with the external threads engaging the internal threads of the drive ring so that rotation of the drive ring causes an axial displacement of the drive nut;   at least one actuator pin connected to the drive nut that is adapted to extend into the water pump housing to the variable flow impeller; and   a motor connected to the drive gear for rotation of the gear in either direction to vary an output from the variable flow impeller.   
     
     
         2 . The external actuator for a variable water pump of  claim 1 , wherein the drive gear is a worm screw and the external teeth are worm gear teeth. 
     
     
         3 . The external actuator for a variable water pump of  claim 2 , further comprising a torsion spring connected to a shaft supporting the worm screw. 
     
     
         4 . The external actuator for a variable water pump of  claim 1 , wherein the internal and external threads are multi-lead threads, and the drive ring is adapted to rotate less than 180° for actuation. 
     
     
         5 . The external actuator for a variable water pump of  claim 4 , wherein the drive ring is adapted to rotate less than 90°. 
     
     
         6 . The external actuator for a variable water pump of  claim 1 , wherein the actuator housing has a hollow center, and is adapted to be fastened to the water pump housing about the drive shaft. 
     
     
         7 . The external actuator for a variable water pump of  claim 1 , wherein there are a plurality of the actuator pins, and a return spring is located around each of the actuator pins that are adapted to move the drive nut to a failsafe position. 
     
     
         8 . The external actuator for a variable water pump of  claim 1 , wherein the internal and external threads are not self-locking. 
     
     
         9 . The external actuator for a variable water pump of  claim 1 , wherein the variable flow impeller includes an impeller fixed to the drive shaft and an axially displaceable shroud, and the at least one actuator pin is adapted to be connected to the shroud for axial movement of the shroud in order to vary an output of the water pump. 
     
     
         10 . The external actuator for a variable water pump of  claim 9 , wherein the shroud is rotatable with the impeller, and the at least one actuator pin is connected to a contact ring that presses against the shroud. 
     
     
         11 . A variably actuatable water pump, comprising:
 a pump housing having at least a part of a pump chamber;   a drive shaft extending through the pump housing from a drive side of the water pump to the pump chamber, with a drive wheel connected to a drive side end of the drive shaft;   a variable flow impeller located in the pump chamber, including an axially fixed impeller part connected to the drive shaft and an axially movable shroud, movable relative to the axially fixed impeller part from a first position in which blades connected to the impeller part are exposed in order to pump coolant, to a second position in which the blades are covered in order to prevent pumping of the coolant;   an external actuator connected to the pump housing, including:
 an actuator housing; 
 a drive ring rotatably mounted in the actuator housing, the drive ring having external teeth and an internal thread; 
 a drive gear engaged with the external teeth of the drive ring, the drive gear being rotatably mounted in the actuator housing; 
 a drive nut having external threads located within the drive ring with the external threads engaging the internal threads of the drive ring so that rotation of the drive ring causes an axial displacement of the drive nut; 
 at least one actuator pin connected to the drive nut that extends into the water pump housing to the variable flow impeller; and 
 a motor connected to the drive gear for rotation of the gear in either direction to vary an output from the variable flow impeller. 
   
     
     
         12 . The variable water pump of  claim 11 , wherein the actuator housing has a hollow center, and is adapted to be fastened to the water pump housing about the drive shaft in a space between the drive wheel and the pump housing. 
     
     
         13 . The variable water pump of  claim 11 , further comprising a seal located between the at least one actuator pin and the pump housing. 
     
     
         14 . The variable water pump of  claim 11 , further comprising a return spring located around the at least one actuator pin that presses against the pump housing and the drive nut to move the drive nut and the shroud to the first position as a failsafe.