Controllable coolant pump with an actuator that can be activated hydraulically

Abstract

A coolant pump for an engine with a controllable coolant flow, including a pump housing in which a hollow pump shaft is rotatably supported with an associated impeller. A volume flow of the pump is influenced by a guide plate allocated to the impeller. The guide plate is rotationally locked to a push rod guided in the pump shaft and continuously variable between two axial end positions via an actuator, provided as a radial piston pump integrated within the coolant pump that is adjustable by a cam and includes, for generating pressure, a piston that is enclosed on the outside by the cam and guided in the radial direction in a bore of the pump shaft and allocated to a pressure space. The pressure space is connected indirectly to a high pressure space in which a high pressure piston applying a force on the push rod is displaceably guided.

1 . Coolant pump of an internal combustion engine with a controllable coolant flow, comprising a pump housing in which a pump shaft constructed as a hollow shaft is supported so that it can rotate with an associated impeller and feeds a coolant via a suction connection into a pressure channel of the coolant pump, a volume flow or a displacement volume of the coolant pump is influenced by a guide plate allocated to the impeller via an actuator, the guide plate is connected rotationally locked to a push rod guided in the pump shaft and continuously variable between two end positions in an axial direction, the actuator comprises a radial piston pump that is integrated within the coolant pump and is adjustable via a cam and includes, for generating pressure, at least one oscillating piston or suction piston that is enclosed on an outside by the cam and is guided in a radial direction in a passage bore of the pump shaft and is allocated to a pressure space, and the pressure space is connected indirectly to a high pressure space in which a high pressure piston applying a force on the push rod is guided in a displaceable manner. 
     
     
         2 . Coolant pump according to  claim 1 , wherein a cam carriage or slide is provided that can move continuously in a radial direction in the pump housing, the carriage or slide has a receptacle in which a cylindrical sleeve or an outer ring of a roller bearing is positioned, and the piston of the radial piston pump is guided on an inside of an inner ring of the roller bearing or the sleeve and an adjustment of the cam carriage influences an eccentricity (E) and thus a stroke of the piston. 
     
     
         3 . Coolant pump according to  claim 1 , wherein the radial piston pump includes two of the pistons offset relative to each other by 180°, and at least one of the pistons is fixed in rotation on the inner ring of the roller bearing. 
     
     
         4 . Coolant pump according to  claim 3 , wherein a spring element is inserted between the pistons of the radial piston pump. 
     
     
         5 . Coolant pump according to  claim 2 , wherein the piston for rotational coupling has a piston peak rounded on an end that engages with a positive fit in a complementarily shaped receptacle of the roller bearing inner ring. 
     
     
         6 . Coolant pump according to  claim 1 , wherein, in a suction phase of the piston, coolant flows out from the coolant pump via a suction valve constructed as a one-way valve into the pressure space. 
     
     
         7 . Coolant pump according to  claim 1 , wherein a closing valve is inserted between the pressure space and the high pressure space, and the closing valve allows a flow of coolant from the pressure space into the high pressure space when there is a pressure drop between the two pressure spaces. 
     
     
         8 . Coolant pump according to  claim 1 , wherein a leakage gap is provided between the high pressure piston and a bore wall of the high pressure space. 
     
     
         9 . Coolant pump according to  claim 1 , wherein an open overpressure valve inserted in the high pressure piston guarantees a coolant flow from the high pressure space via a drainage channel of the push rod into an outflow opening of the pump shaft. 
     
     
         10 . Coolant pump according to  claim 2 , wherein the cam carriage is adjustable by a hydraulically, electronically, or pneumatically acting control element. 
     
     
         11 . Coolant pump according to  claim 10 , wherein, for fault protection, at least one of the cam carriage or the push rod interacts with a fail safe device constructed as a spring element.