Processing

Please wait...

Settings

Settings

Goto Application

1. EP2024112 - METHOD OF OPERATING A HYDRAULIC PRESSING UNIT, AND HYDRAULIC PRESSING UNIT

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

Claims

1. Method for operating a hydraulic pressing unit (1), in particular a manual pressing unit, the pressing unit (1) comprising a hydraulic pump, a moving part (7), a stationary part (11) and a return valve (16), the moving part (7) further being moved into a pressing position by the build-up of hydraulic pressure obtained by using the hydraulic pump to fill a hydraulic chamber (6) with hydraulic medium from a supply chamber (5), the moving part (7) further being designed to automatically move from the pressing position back into an end position by the action of a restoring spring (15) and the return valve (16) being designed to close only after the pressure drops below a certain pressure acting on the return valve (16) due to the hydraulic medium running back, characterised in that, in order to act on the hydraulic medium upstream of the return valve (16) that flows when said return valve (16) is open, means (25) are provided which counteract the flow of the hydraulic medium in such a way that a pressure drop that occurs leads to the return valve (16) being shifted into the closed position.
  2. Method according to claim 1, characterised in that the flow is acted on by briefly decoupling some of the hydraulic medium, the decoupling preferably taking place by moving a control piston (26) that is arranged in the flow path counter to the direction of flow.
  3. Method according to any of the preceding claims, characterised in that the control piston (26) leaves a flow passage in the non-actuated outflow position and leads to the flow being shut off in the actuated pumping position, the control piston (26) preferably being moved out of the outflow position into the pumping position by pumping hydraulic medium out of the supply chamber (5) into the hydraulic chamber (6), and/or in that, in the return direction of the moving part (7), the control position (26) is arranged beyond the end position of the moving part (7).
  4. Hydraulic pressing unit (1) comprising a hydraulic pump, a moving part (7), a stationary part (11) and a return valve (16), the moving part (7) being moved from a starting position into a pressing position as a result of filling a hydraulic chamber (6) with hydraulic medium from a supply chamber (5) by means of the hydraulic pump, the return valve (16) being automatically moved into an open position in dependence on a hydraulic pressure corresponding to the pressing position and the moving part (7) returning by the action of a restoring spring (15), characterised in that means (25) are provided which act on the flow of the hydraulic medium with the effect of lowering the pressure in such a way that the return valve (16) is moved into the closed position.
  5. Pressing unit according to claim 4, characterised in that the hydraulic chamber (6) comprises a first sub-chamber (45) in which the moving part (7) moves and a second sub-chamber (46), which is formed as a line portion, in which the hydraulic medium for filling or emptying the first sub-chamber (45) flows, and in that the means (25) are arranged in the second sub-chamber, the means (25) preferably being designed to briefly decouple some of the hydraulic medium, and/or in that the means (25) are formed in the line portion for switching between a first line path and a second line path, the decoupling taking place during the switchover.
  6. Pressing unit according to either claim 4 or claim 5, characterised in that the means (25) consist of a control piston (26) that moves in the second sub-chamber (46), the piston shaft (32) preferably being designed to open or close a hydraulic line (36) connected downstream of the hydraulic pump, and/or in that the piston head (33) is designed to open or close an outflow line (37) leading to the return valve (16).
  7. Pressing unit according to any of claims 4 to 6, characterised in that the control piston (26) has three impact surfaces (42, 43, 44) which are separate from one another and/or in that a first continuous impact surface (42) of the control piston (26) is associated with the first sub-chamber (45).
  8. Pressing unit according to any of claims 4 to 7, characterised in that a second impact surface (44) that is arranged opposite the first impact surface (42) is associated with the outflow line (37) and/or in that a third impact surface (43) that is also arranged opposite the first impact surface (42) is associated with the hydraulic pump.
  9. Pressing unit according to any of claims 4 to 8, characterised in that the second impact surface (44) and the third impact surface (43) together correspond in terms of size to the first impact surface (42).
  10. Pressing unit according to any of claims 4 to 9, characterised in that the control piston (26) can be moved between an outflow position and a pumping position.
  11. Pressing unit according to any of claims 4 to 10, characterised in that, in the outflow position, the piston head (33) is housed in an annular chamber (50) having an enlarged diameter in comparison with the piston head (33), which annular chamber (50) transitions into the outflow line (37).
  12. Pressing unit according to any of claims 4 to 11, characterised in that, in the outflow position, the control piston (26) acts as a slide to close the hydraulic line (36) and/or in that, in the pumping position, the control piston (26) acts as a slide to close the outflow line (37).
  13. Pressing unit according to any of claims 4 to 12, characterised in that the control piston (26) has an integrated pressure relief valve (47), the pressure relief valve (47) preferably being formed by a disc-spring-like valve disc (49) that is secured by means of a pin.
  14. Pressing unit according to any of claims 4 to 13, characterised in that the pin is formed as a screw (48).
  15. Pressing unit according to any of claims 4 to 14, characterised in that the control piston (26), part of the outflow line (37) and part of the hydraulic line (36) are formed in an insert part (27) which is inserted as a whole into a bore-like continuation (28) of the first sub-chamber (45).