Hydraulic unit and method for providing a pressurized hydraulic fluid

Abstract

An hydraulic unit provides a pressurized hydraulic fluid at an outlet. The unit has an electric motor and a pump operated by the motor for generating pressure. A reservoir having a variable compensation volume stores the hydraulic fluid primed by the pump in a gas-free manner. The hydraulic fluid is especially pressurized in order to safely and reliably guarantee that the hydraulic fluid is gas-free. The inventive design allows for the safe and operationally reliable use of the hydraulic unit even at high acceleration values. The hydraulic unit is especially adapted for use in an industrial robot.

1 - 20 . (canceled)  
     
     
         21 . An hydraulic unit for providing a pressurized hydraulic fluid at an outlet, comprising: 
 an electric motor;    at least one pump for pressure generation driven by said electric motor;    a storage space configured with a variable compensating volume; and    an amount of the hydraulic fluid enclosed free of gas in said storage space and fluidically connected to a suction side of said at least one pump.    
     
     
         22 . The hydraulic unit according to  claim 21 , wherein the hydraulic fluid is disposed in said storage space with an overpressure.  
     
     
         23 . The hydraulic unit according to  claim 22 , wherein the overpressure is approximately in a region of several 10 5  Pa.  
     
     
         24 . The hydraulic unit according to  claim 23 , wherein the overpressure lies between 3 and 50×10 5  Pa.  
     
     
         25 . The hydraulic unit according to  claim 21 , wherein said storage space includes a compensating wall displaceably mounted in form of a piston and sealing against a stationary housing wall of said storage space.  
     
     
         26 . The hydraulic unit according to  claim 25 , wherein said compensating wall is disposed to be subject to a counterforce.  
     
     
         27 . The hydraulic unit according to  claim 26 , wherein said compensating wall bounds a pressure space with a connection for a pressure medium on an outside facing away from said storage space.  
     
     
         28 . The hydraulic unit according to  claim 26 , which comprises a spring element disposed to generate the counterforce.  
     
     
         29 . The hydraulic unit according to  claim 28 , wherein said spring element is a securing spring.  
     
     
         30 . The hydraulic unit according to  claim 21 , which comprises a housing forming an inner housing space, and wherein said electric motor and said pump are disposed in said inner housing space, and said inner housing space forms said storage space filled with the hydraulic fluid.  
     
     
         31 . The hydraulic unit according to  claim 30 , which comprises a function block disposed to close off said housing and formed with the outlet, and wherein a plurality of hydraulic components are integrated in said function block.  
     
     
         32 . The hydraulic unit according to  claim 31 , wherein said function block is configured for controlling and routing the hydraulic fluid provided at the outlet.  
     
     
         33 . The hydraulic unit according to  claim 31 , which comprises a line connecting said pump to said function block, and wherein all further hydraulic components following said pump are integrated in said function block.  
     
     
         34 . The hydraulic unit according to  claim 21 , wherein said pump is one of at least two pumps for providing a low-pressure part stream and a high-pressure part stream, respectively.  
     
     
         35 . The hydraulic unit according to  claim 34 , wherein said pumps are jointly driven by said electric motor.  
     
     
         36 . The hydraulic unit according to  claim 34 , which comprises a valve assembly configured to provide in each case only one part stream at the outlet.  
     
     
         37 . The hydraulic unit according to  claim 36 , wherein said valve assembly is configured to enable switching one of the part streams to pressureless in each case.  
     
     
         38 . The hydraulic unit according to  claim 21 , wherein said electric motor is a controlled motor for setting a predetermined profile of the pressure of the hydraulic fluid at the outlet.  
     
     
         39 . The hydraulic unit according to  claim 21 , wherein said electric motor is a servomotor.  
     
     
         40 . The hydraulic unit according to  claim 21 , which comprises a connector for connection to a machine tool.  
     
     
         41 . The hydraulic unit according to  claim 40  connected, via said connector, to a rivet setting appliance.  
     
     
         42 . In combination with a machine part that is subject to accelerations during operation, the hydraulic unit according to  claim 21  disposed on the machine part.  
     
     
         43 . A method of providing a pressurized hydraulic fluid, which comprises: 
 providing an hydraulic unit and driving a pump of the hydraulic unit for pressure generation with an electric motor;    supplying the pump with hydraulic fluid from a storage space having a variable compensating volume, wherein the hydraulic fluid is stored in the compensating volume free of gas.