Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B20/00—Safety arrangements for fluid actuator systems; Applications of safety devices in fluid actuator systems; Emergency measures for fluid actuator systems
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
  • B30B15/16—Control arrangements for fluid-driven presses
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/205—Systems with pumps
  • F15B2211/20507—Type of prime mover
  • F15B2211/20515—Electric motor
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/205—Systems with pumps
  • F15B2211/2053—Type of pump
  • F15B2211/20561—Type of pump reversible
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
  • F15B2211/27—Directional control by means of the pressure source
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
  • F15B2211/00—Circuits for servomotor systems
  • F15B2211/30—Directional control
  • F15B2211/305—Directional control characterised by the type of valves
  • F15B2211/3056—Assemblies of multiple valves
  • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve

Definitions

• the invention relates to an electro-hydraulic control for a safe electro-hydraulic axis.
• electro-hydraulic controls are used for example in presses or in injection molding machines, as well as in many other applications of industrial automation.
• Conventional presses are often valve-controlled. Via a proportional valve, a speed or a pressing force of a press cylinder are set.
• Safety requirements with regard to safety at work can be implemented, for example, by switching valves which block a hydraulic connection to the press cylinder in an unactuated position. The switching valves are also monitored by a switch which detects the switching position.
• the DIN EN 12622: 2001 shows in Annex C an example of a hydraulic press control circuit, are implemented in the safety requirements or occupational safety requirements.
• DE 103 29 067 A1 discloses an electro-hydraulic control for a press with a driven by a variable-speed drive hydraulic pump is disclosed.
• a cylinder space of a press cylinder over which a piston of the press cylinder in a press tion with a pump pressure of the hydraulic pump can be acted upon, is in direct pressure fluid connection with the hydraulic pump.
• An annular space of the press cylinder for pressurizing the piston against the pressing direction is connected to a hydraulic accumulator, which is charged via the hydraulic pump.
• a pressure relief valve is provided to limit the pressure of the pump pressure.
• Press cylinder in the pressing direction for example in an emergency situation, can be done only by stopping the hydraulic pump.
• the object of the present invention is to provide a reliable and as simple as possible or cost-effective implementation of occupational safety requirements in an electro-hydraulic control, which has a variable speed driven hydraulic machine. This object is achieved by an electro-hydraulic control according to claim 1.
• an electrohydraulic control for a safe electrohydraulic axle which comprises at least one hydraulic consumer.
• the control is used in particular for a press, an upper piston press or a press brake.
• the controller has a valve block with a first working port and a second working port for the hydraulic consumer.
• the valve block has two supply ports for a pressure medium supply and a pressure medium discharge. Fluidic paths are provided between at least one of the working ports and at least one of the supply ports.
• a hydraulic machine is connected between the two supply connections. This is coupled to an electric drive having an actuator for adjusting its speed.
• On the valve block further monitored switching valves are arranged, which is assigned to monitor their switching position in each case a monitoring device.
• two monitored switching valves are arranged one behind the other.
• at least two independent mutually effective security means present, which limit a supply of pressure medium in the second working port in a predetermined state.
• the valves which are flown through in the normal operating cycle - also all the monitored valves - are designed as switching valves, as a result of which throttle losses which occur with proportional valves are reduced.
• the safety means comprise at least one monitored switching valve arranged in a bypass path from the second working port to a tank. Due to the arrangement in the bypass path, the switching valve is flowed through only in emergency operation of pressure medium and thus causes in normal operation substantially no flow resistance.
• the safety means in each path which allows a pressure fluid supply to the second working port, comprise at least one monitored switching valve.
• the security means in each path which allows a pressure medium supply to the second working port, two monitored switching valves, whereby a high reliability is ensured.
• the safety means comprise a safety device on the electric drive of the hydraulic machine. This safety device forces a shutdown or an operating state with reduced power of the electric drive as a function of a release signal supplied to it.
• the safety means comprise a monitored switching valve, which fluidly connects the two supply ports in an unactuated position, whereby the supply of the hydraulic consumer is stopped with pressure medium.
• FIG. 1 in a hydraulic circuit diagram, an electro-hydraulic control according to an embodiment
• the switching valves 12, 16, 18 are thus successively in a path from the hydraulic machine 8 to the annular space 30 of the hydraulic cylinder 2. In the unconfirmed basic position a, the switching valves 12, 16 each interrupt this path in both pressure medium flow direction and the switching valve 18 in a pressure medium flow direction.
• a valve spool of the switching valve 14 is biased by the spring 33 in a basic position a, in which the pressure line 48 connected to the shuttle valve 50 is connected to the control line 54 and the tank line 38 to the working line 52.
• About the actuator 34 of the valve spool of the switching valve 14 in a switching position b can be brought, in which the pressure line 48 with the working line 52 and the tank line 38 with the control line 54 are in fluid communication.
• the check valve 56 which can be unlocked with a control pressure of the control line 54 is arranged between the tank 42 and the cylinder chamber 29 of the hydraulic cylinder 2.
• a valve body of the check valve 56 is biased by a spring on a valve seat.
• the check valve 56 opens in the pressure medium flow direction from the tank 42 to the cylinder chamber 29.
• the pressure port Z1 of the cylinder chamber 29 is disposed between the check valve 56 and the cylinder chamber 29.
• Another check valve 60 is arranged in the pressure line 48 between the shuttle valve 50 and the switching valve 14, which opens in the pressure fluid flow direction from the shuttle valve 50 to the switching valve 14.
• a check valve 61 in the tank channel 38 By a check valve 61 in the tank channel 38, a flow of pressure medium only in the direction of the tank 42 is possible.
• control line 54 is throttled between the switching valve 14 and the check valve 56.
• a pressure fluid flow path from the annular space 30 of the hydraulic cylinder 2 to the tank 42 is secured by a pressure limiting valve 84 which is set above the maximum nominal pressure of the hydraulic machine 8 and opens at a pressure in the annular space 30 of 350 bars, for example.
• This also has a small nominal size, e.g. NG 4, so that in case of release, the hydraulic cylinder 2 extends only slowly.
• a pressure limiting valve 88 or 90 connected to the tank 42 is likewise arranged.
• the pressure limiting valve 88 opens approximately at a pressure of 315 bar in the first working line 24 and the pressure relief valve 90 approximately at a pressure of 200 bar in the second working line 24.
• each working line 24 and 26 is connected to a suction line 92 and 94, respectively, which are in fluid communication with the tank 42.
• opening check valve 96, 98 is arranged. Due to the suction lines 92, 94 pressure fluid can be sucked out of the tank 42 by the hydraulic machine 8 in the absence of pressure medium.
• the cylinder chamber 29 of the hydraulic cylinder 2 is protected by the switching valve 12 against inadvertent supply of pressure medium.
• the two connections A1, A2 of the hydraulic machine 8 are connected and the consumer connections A, B of the Switching valve 12 locked.
• the switching valve 14 in the unactuated position, a bypass connection from the cylinder chamber 29 of the hydraulic cylinder 2, via the pressure line 32, the working line 52 and the tank channel 38 to the tank 42 ago.
• the electric drive 6 is included in the safety concept.
• Drive 6 has a secure control electronics, which only after the presence of a release signal of the switch 20, the drive 6 in the normal operating state in which the drive 6 converts control signals, switches. If the release signal is not present, the drive 6 is stopped or only with low power, i. operate with low torque or low speed.
• the press brake 1 is at a standstill.
• the switching valves 12 to 18 are in their unactuated currentless home position a.
• the first and the second working line 24, 26 of the hydraulic machine 8 are connected to each other via the switching valve 12 and the second working line 26 is in addition via the pump channel 37, the switching valve 16 and the tank channel 38 to the tank 42 in fluid communication.
• these fluid flow paths have been highlighted with a dashed line having a large line width.
• the pressure medium flow path from the annular chamber 30 of the hydraulic cylinder 2 is also highlighted with a dashed line having a large line width and ends at the switching valve 18 and the pressure limiting valve 84, 86th
• the switching valves 12, 16, 18 are arranged, which are each monitored by the switch 20.
• the monitoring has the purpose that the hydraulic machine 8 promotes pressure fluid from the annulus 30 into the cylinder chamber 29 of the hydraulic cylinder 2 only when the switching valves 12, 16, 18 are in the switching position b.
• the switches 20 report the switching position b to the electronics 4, which controls the electric drive 6. To stop the rapid traverse, one of the switching valves 12, 16, 18 is simply switched to the initial position b without a current.
• FIG. 3 the switching positions of the electro-hydraulic control for the press brake 1 for a crawl of the piston 28 of the hydraulic cylinder 2 are shown.
• the switching valves 12, 14 and 16 are actuated and the switching valve 18 is not actuated.
• the non-actuated switching valve 18 is a pressure medium flow path (having large line thickness dashed line in FIG. 3) between the annular space 30 of the hydraulic cylinder 2 and the hydraulic machine 8 only via the pressure limiting valve 86.
• This opens only at a certain annulus pressure in the annular space 30, for example, 90 bar, which causes this annulus pressure counteracts the working pressure in the cylinder chamber 29, whereby the adjustment speed of the piston 28 of the hydraulic cylinder 2 is reduced and this is moved in crawl.
• FIG 4 shows the switching positions of the electro-hydraulic control for a decompression of the hydraulic cylinder 2 of the press brake 1.
• the hydraulic machine 8 promotes hydraulic pump as pressure medium from the cylinder chamber 29 of the hydraulic cylinder 2 to the tank 42.
• This pressure medium from the cylinder chamber 29, via the pressure line 32, the switching valve 12, the first working line 24, the second working line 26, the switching valve 16 to the tank 42 promoted ,
• the press brake 1 is thus relieved, since the working pressure in the cylinder chamber, 29 of the hydraulic cylinder 2 is reduced.
• the piston 28 of the hydraulic cylinder 2 is moved upwards in rapid traverse.
• the switching valves 12 and 16 are actuated. Pressure medium is thus promoted by the cylindrical space 29 of the hydraulic cylinder 2 via the pressure line 32, the switching valve 12, the first working line 24, the second working line 26, the switching valve 12, the switching valve 16, the switching valve 18 and the annular space channel 44 to the annular space 30.
• the check valve 56 is controlled by the pressure in the control line 54, which is connected via the switching valve 14, the shuttle valve 50 and connected to the second working line 26 pump channel 37.
• the following table gives an overview of the sections of the machine cycle described above in FIGS. 1 to 5. It also indicates, by marking the respective table field, which of the switching valves 12, 14, 16, 18 are actuated in the respective cycle section.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• General Engineering & Computer Science (AREA)
• Fluid-Pressure Circuits (AREA)

Priority Applications (2)

Applications Claiming Priority (4)

Publications (1)

Family

ID=43307926

Family Applications (1)

Country Status (4)

Cited By (5)

Families Citing this family (7)

Citations (3)

Family Cites Families (2)

• 2009
  • 2009-12-15 DE DE102009058408A patent/DE102009058408A1/de not_active Withdrawn
• 2010
  • 2010-06-17 EP EP10732281.0A patent/EP2452080B1/de active Active
  • 2010-06-17 WO PCT/EP2010/003669 patent/WO2011003506A1/de active Application Filing
  • 2010-06-17 CN CN201080035124.3A patent/CN102549273B/zh not_active Expired - Fee Related

Patent Citations (3)

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