Hydraulic oscillator as a drive of machines

• US 6,647,719 B2
• Filed: 01/24/2002
• Issued: 11/18/2003
• Est. Priority Date: 02/17/2001
• Status: Expired due to Fees

• Current Assignee: Globemag LP
• Original Assignee: Globemag LP
• Inventors: Truninger, Rolf
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): Lazo, Thomas E.
• Application Number:
  US10/056,138
• Publication Number:
  US 20020112476A1
• Time in Patent Office: 663 Days
• Field of Search: 604/13, 604/14, 604/16, 604/17, 604/45, 604/46, 604/73, 604/75, 604/76, 921/34
• US Class Current: 60/414
• CPC Class Codes: B29C 2045/7673 Recovering energy or power from drive motors
• CPC Class Codes: B29C 45/5008 Drive means therefor
• CPC Class Codes: B29C 45/681 using a toggle mechanism as mould clamping device
• CPC Class Codes: B29C 45/7666 of power or energy, e.g. integral function of force
• CPC Class Codes: B30B 1/16 operated by fluid-pressure means
• CPC Class Codes: F15B 1/024 used as a supplementary power source, e.g. to store energy in idle periods to balance pump load
• CPC Class Codes: F15B 21/12 Fluid oscillators or pulse generators
• CPC Class Codes: F15B 21/14 Energy-recuperation means
• CPC Class Codes: F15B 7/006 Rotary pump input
• CPC Class Codes: Y02P 70/10 Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

Abstract

The invention proposes a novel drive with electrical power control for machines which have to execute cyclic movements with high accelerations. An electric motor drives a pump which, in turn, is connected directly to a cylinder. This arrangement has added to it a system of pressure accumulators and valves which give the system the property of an oscillator. The acceleration forces in the event of a cyclic movement near to resonance are then exerted largely by the pressure accumulators and the cylinders connected to these. This leads to a relieving of the electric motor and makes it possible to install lower powers on the machine or else, for the same power, achieve shorter cycle times of the machine.

Claims

1. A device for driving a machine element, comprising:

a hydraulic actuator operatively connected to a machine element and having a first cylinder and a first piston reciprocating in the first cylinder;

a hydraulic pump connected in a dosed hydraulic circuit to the actuator;

a variable-speed electric motor which drives the hydraulic pump; and

at least one energy accumulator operatively connected to a member selected from the group consisting of piston and machine element to only apply a potential force on the member in dependence on a position of the member, wherein the energy accumulator is loaded or unloaded in response to a movement of the member.

2. The device of claim 1, and further comprising at least one valve or a coupling for separating the at least one energy accumulator from the hydraulic actuator.

3. The device of claim 1, and further comprising a valve for regulating a fluid flow from the pump to the at least one energy accumulator.

4. The device of claim 1, wherein the hydraulic actuator is an element selected from the group consisting of hydraulic cylinder, hydraulic cylinder with a continuous piston rod, pivoting piston, hydraulic pump and hydraulic motor.

5. The device of claim 1, configured for use to drive a shaft of a crane, press, forming press, bending press, shears, stretch-straightening machine, testing machine, lifting platform of a punching machine, injection-moulding machine, die-casting machine or other machine.

7. The device of claim 1, wherein the electric motor is a member selected from the group consisting of permanently excited synchronous motor, vector-regulated asynchronous motor, direct-current motor, brushless DC motor, and switched reluctance motor.

8. The device of claim 1, and further comprising an internally or externally toothed, compensated or non-compensated gear pump, a constant or variable displacement axial or radial piston pump, a constant or variable displacement vane-cell pump, a screw pump or another hydrostatic displacement unit.

9. The device of claim 1, wherein the hydraulic actuator has a second cylinder and a second piston reciprocating in the second cylinder and subdividing the second cylinder in two compartments, with the pump further connected to one of the compartments of the second cylinder, said first and second pistons being interconnected, and further comprising a valve for regulating a fluid flow from the pump to the at least one energy accumulator.

10. The device of claim 1, and further comprising a second energy accumulator fluidly connected to the pump, said second energy accumulator, said pump and said at least one energy accumulator being placed in series.

11. The device of claim 1, wherein the piston subdivides the cylinder in two compartments, with the pump connected to one compartment of the first cylinder of the actuator, said energy accumulator fluidly connected to the other one of the compartments of the cylinder.

12. The device of claim 11, wherein the hydraulic actuator has a second cylinder and a second piston reciprocating in the second cylinder and subdividing the second cylinder in two compartments, said pump connected to one of the compartments of the second cylinder of the actuator, and further comprising a second energy accumulator operatively connected to the other one of the compartments of the second cylinder of the hydraulic actuator, wherein the at least one energy accumulator and the second energy accumulator are filled or discharged in response to a movement of the member.

13. The device of claim 11, wherein the hydraulic actuator has a second cylinder and a second piston reciprocating in the second cylinder and subdividing the second cylinder in two compartments, with the pump further connected to one of the compartments of the second cylinder, and further comprising a second energy accumulator fluidly connected to the other one of the compartments of the second cylinder.

14. The device of claim 13, wherein the first and second pistons are interconnected.

15. The device of claim 11, wherein the hydraulic actuator has a second cylinder and a second piston reciprocating in the second cylinder and subdividing the second cylinder in two compartments, with the pump further connected to one of the compartments of the second cylinder, said at least one energy accumulator further connected to the other one of the compartments of the second cylinder.

16. The device of claim 11, wherein the at least one energy accumulator is connected directly with the other one of the compartments of the first cylinder in parallel to the closed hydraulic circuit.

17. The device of claim 1, wherein the energy accumulator is a spring.

6. The device of clam 1, and further comprising sensors configured to measure pressures, positions or time derivations thereof, and an electronic control receiving a signal in response to the measurement from the sensors.