Double-flow pump unit, and method for controlling same

Abstract

A pump unit includes an electric motor and a pump with a duct. The pump is rotationally driven by the electric motor to provide a setpoint volumetric flow to the duct. A rotational speed controller is configured to, during operation of the pump, determine a setpoint rotational speed based on a fixed-point iteration of an initial rotational speed. The setpoint rotational speed is associated with a setpoint volumetric flow. The rotational speed controller is further configured to operate the pump at the setpoint rotational speed.

1 . A pump unit, comprising:
 an electric motor;   a pump having a duct and being rotationally driven by the electric motor to provide a setpoint volumetric flow to the duct, and   a rotational speed controller configured to:   during operation of the pump, determine a setpoint rotational speed of the pump based on a fixed-point iteration of an initial rotational speed of the pump, wherein the setpoint rotational speed is associated with a setpoint volumetric flow; and   operate the pump at the setpoint rotational speed.   
     
     
         2 . The pump unit according to  claim 1 , wherein the pump includes a second duct, the pump being rotationally driven by the electric motor to provide a second setpoint volumetric flow to the second duct. 
     
     
         3 . The pump unit according to  claim 2 , wherein the duct and the second duct are hydraulically coupled to one another via a pressure-limiting valve. 
     
     
         4 . The pump unit according to  claim 2 , wherein the duct is a high-pressure duct configured to actuate a component, and the second duct is a low-pressure duct configured to provide a fluid supply to the component, and wherein the component is a clutch, a parking lock, or a disk set of a variator of a continuously variable belt transmission. 
     
     
         5 . A method for controlling a pump unit, comprising:
 determining an initial rotational speed of the pump based on an efficiency of the pump and a required setpoint volumetric flow, wherein the efficiency is a maximum efficiency for the pump or is equal to one;   determining a setpoint rotational speed based on a specified number of iteration steps of the initial rotational speed and a correction value from the efficiency of the pump, wherein the correction value is determined based on the initial speed and the setpoint volumetric flow, wherein the setpoint rotational speed is associated with a setpoint volumetric flow; and   operating the pump at the setpoint rotational speed.   
     
     
         6 . The method according to  claim 5 , wherein the specified number of iteration steps is odd. 
     
     
         7 . The method according to  claim 5 , further comprising applying a safety value to the setpoint rotational speed. 
     
     
         8 . The method according to  claim 5 , wherein the pump unit includes two ducts separate from each other, the method further comprising:
 determining the initial rotational speed of the pump for each duct based on the efficiency of the pump for respective duct and the required setpoint volumetric flow for each duct;   determining the setpoint rotational speed of the pump for each duct based on the specified number of iteration steps of the initial rotational speed for the respective duct and the correction value of the efficiency for the respective duct; and   operating the pump at a maximum of the determined setpoint rotational speeds.   
     
     
         9 . The method according to  claim 5 , wherein the pump includes two ducts connected to each other via a hydraulic coupling, the method further comprising:
 determining the initial rotational speed of the pump for each duct based on the efficiency of the pump for respective duct and the required setpoint volumetric flow for each duct;   determining the setpoint rotational speed of the pump for each duct based on the specified number of iteration steps of the initial rotational speed for the respective duct and the correction value of the efficiency for the respective duct;   determining a corrected setpoint rotational seed based on a maximum of the determined setpoint rotational speeds, and a volume exchange via the hydraulic coupling; and   operating the pump at the corrected setpoint rotational speed.   
     
     
         10 . The method according to  claim 9 , wherein a size of the volume exchange is determined from the efficiencies of the pump for the ducts at the maximum of the determined setpoint rotational speeds. 
     
     
         11 . The pump unit according to  claim 2 , wherein the rotational speed controller is further configured to determine a second setpoint rotational speed based on a fixed-point iteration of a second initial rotational speed of the pump, the second setpoint rotational speed being associated with the second setpoint volumetric flow. 
     
     
         12 . The pump unit according to  claim 11 , wherein the rotational speed controller is further configured to operate the pump at a maximum of the setpoint rotational speed and the second setpoint rotational speed. 
     
     
         13 . The pump unit according to  claim 11 , wherein the rotational speed controller is further configured to selectively operate the pump at one of the setpoint rotational speed or the second setpoint rotational speed. 
     
     
         14 . The pump unit according to  claim 11 , wherein the rotational speed controller is further configured to determine the second initial rotational speed based on a desired setpoint volumetric flow through the second duct and a displacement volume of the pump through the second duct. 
     
     
         15 . The pump unit according to  claim 14 , wherein the rotational speed controller is further configured to determine the second setpoint rotational speed further based on an efficiency of the pump operating via the second duct. 
     
     
         16 . The pump unit according to  claim 11 , wherein the rotational speed controller is further configured to determine the initial rotational speed based on a desired setpoint volumetric flow through the duct and a displacement volume of the pump through the duct. 
     
     
         17 . The pump unit according to  claim 16 , wherein the rotational speed controller is further configured to determine the setpoint rotational speed further based on an efficiency of the pump operating via the duct. 
     
     
         18 . The pump unit according to  claim 1 , wherein the rotational speed controller is further configured to determine the initial rotational speed based on a desired setpoint volumetric flow and a displacement volume of the pump. 
     
     
         19 . The pump unit according to  claim 18 , wherein the rotational speed controller is further configured to determine the setpoint rotational speed further based on an efficiency of the pump. 
     
     
         20 . The pump unit according to  claim 3 , wherein the rotational speed controller is further configured to:
 determine a volume exchange via the hydraulic coupling based on an efficiency, at the maximum setpoint rotational speed, of the pump for each duct;   determine a corrected setpoint rotational speed based on the volume exchange and the maximum setpoint rotational speed; and   operate the pump at the corrected setpoint rotational speed.