LABYRINTHINE RADIAL PISTON-HYDRAULIC VARIABLE WATERPUMP ACTUATION SYSTEM
A regulatable coolant pump of an internal combustion engine having a pump housing in which a pump shaft with an associated impeller is rotatably mounted. The impeller conveys a coolant from an inlet connection into an outlet of the coolant pump, a volume flow of the coolant pump being adjustable by a cover that externally surrounds the impeller at least in some regions and is displaceable by a pressure medium. The cover is moved by an actuator including a solenoid in contact with a piston that is moveable into a piston pressure chamber in order to generate high pressure pulses of a pressure medium that are transmitted to a plunger chamber where they act on a plunger connected to the cover. Upon actuation of the solenoid, the cover is moved by the pressure medium acting on the plunger to an actuated end position.
1 . A regulatable coolant pump of an internal combustion engine, comprising a pump housing in which a pump shaft with an associated impeller is rotatably mounted, that conveys a coolant into an outlet of the coolant pump, a volume flow of the coolant pump being adjustable by a cover that at least one of externally surrounds the impeller at least in some regions or blocks an inlet flow to the coolant pump, the cover is hydraulically displaceable by an actuator between two end positions, the actuator including:
a solenoid in contact with a piston that is moveable into a piston pressure chamber via actuation of the solenoid in order to generate high pressure pulses of a pressure medium,
a return spring that acts to return the piston to an initial position,
a plunger chamber in communication with the pressure chamber via a communication path in order to receive the high pressure pulse of the pressure medium,
a plunger located in the plunger chamber,
a check valve located in the communication path to prevent a backflow of the pressure medium from the plunger chamber;
wherein the plunger is connected to the cover so that upon actuation of the solenoid, the cover is moved by the pressure medium acting on the plunger to an actuated end position in which the impeller is surrounded at least in some regions or the inlet flow to the coolant pump is blocked.
2 . The coolant pump as recited in claim 1 , wherein the communication path extends through the pump shaft.
3 . The coolant pump as recited in claim 2 , wherein the pressure chamber extends radially from the pump shaft in an upper cap that together with a lower cap are connected together around the pump shaft, to radial cross-bores located in the pump shaft, a labyrinth seal being formed by annular projections on the upper and lower caps being received in annular grooves in the pump shaft on either side of the radial cross-bores, and an axial bore in the pump shaft is connected to the plunger chamber which is located at an impeller end of the pump shaft.
4 . The coolant pump as recited in claim 3 , wherein the cover is rotationally fixed to impeller and at least partially covers the impeller blades in the actuated end position.
5 . The coolant pump as recited in claim 1 , wherein a return spring acts on the plunger to return the cover to a non-actuated end position.
6 . The coolant pump as recited in claim 1 , wherein the actuator is connected to the pump housing and the cover comprises a non-rotatable ring that at least partially covers radial ends of the impeller in the actuated end position.
7 . The coolant pump as recited in claim 1 , wherein the actuator is variably actuatable by varying an actuation frequency of the solenoid to adjust a coolant flow through the coolant pump.
8 . The coolant pump as recited in claim 1 , wherein the cover is connected to the pump shaft and covers an inlet of the coolant pump in the actuated end position.
9 . The coolant pump as recited in claim 8 , wherein guide posts are located on the cover and extend through openings in the impeller.
10 . The coolant pump as recited in claim 1 , wherein the pressure chamber extends radially from the pump shaft in an upper cap that together with a lower cap are connected together around the pump shaft, to radial cross-bores located in the pump shaft, a labyrinth seal being formed by annular projections on the upper and lower caps being received in annular grooves in a sleeve located on the pump shaft on either side of the radial cross-bores, and an axial bore in the pump shaft is connected to the plunger chamber which is located at an impeller end of the pump shaft.
11 . The coolant pump as recited in claim 1 , wherein a relief check valve is located in the pressure chamber.
12 . The coolant pump as recited in claim 1 , wherein the piston has radial and axial holes defined therein, and the radial hole is alignable with a coolant relief passage at one stroke position of the piston to recharge piston chamber.
13 . The coolant pump as recited in claim 1 , wherein the pressure medium is the coolant.