Vacuum Generating Device and Method for the Operation Thereof

• US 20100303641A1
• Filed: 11/27/2008
• Published: 12/02/2010
• Est. Priority Date: 12/04/2007
• Status: Active Grant

• Current Assignee: Festo SE & Company KG
• Original Assignee: Festo AG & Company KG (Festo GmbH & Company KG)
• Inventors: Krehl, Yvonne, Medow, Ralf, Bretzler, Markus
• Granted Patent: US 8,678,776 B2
• Time in Patent Office: Days
• US Class Current: 417/188
• CPC Class Codes: B25J 15/0625 provided with a valve
• CPC Class Codes: F04F 5/52 of evacuating pumps

Abstract

The invention relates to a vacuum generating device (1) and to a method suitable for the operation thereof. An ejector device (27) is connected with an inlet (29) thereof to an air supply conduit (32) that can be selectively closed or opened by an electronic control unit (14) in order to selectively turn off or turn on the ejector device (27). When the ejector device (27) is turned on, a vacuum is generated in a suction channel (35). The ejector device (27) is operated such that the vacuum fluctuates between an upper switching value and a lower switching value. By comparison to a reference time value, the operating period of the ejector device (27) is determined in order to generate a diagnosis signal that allows a conclusion of the leak that is present.

Claims

1. A method for the operation of a vacuum generating device, having an ejector device, whose inlet is connected with an air supply conduit and whose suction side is connected with a suction channel, which is connected with a suction gripper, and which has a pressure detection installation for detecting the vacuum in the suction channel, wherein the vacuum in the suction channel is regulated in that the air supply of the inlet is turned off once the vacuum has reached an upper switching value and is switched on again until the upper switching value has been reached once the vacuum drops to a lower switching value, and wherein the regulating time which has passed between the shutting off of the air supply and either the subsequent restarting, or the renewed shutting off of the air supply, is detected and compared with at least one predetermined reference time value in order to generate an electrical diagnostic signal as a function of the result of the comparison.

2. The method in accordance with claim 1, wherein a diagnostic signal is generated when the regulating time falls below the predetermined reference time value.

3. The method in accordance with claim 1, wherein the diagnostic signal is output as an optical and/or acoustic signal.

4. The method in accordance with claim 1, wherein the diagnostic signal is output as an electric signal in such a way that it can be supplied to an external electronic control device.

5. The method in accordance with claim 1, wherein the detected regulation time is compared with several different reference time values in order to generate different electrical diagnostic signals as a function of the length of the regulating time.

6. The method in accordance with claim 1, wherein the lower switching value can be generated by means of an addition of a predetermined safety pressure value to the difference between the variable predeterminable upper switching value and of an also variably predeterminable hysteresis value.

7. The method in accordance with claim 1, wherein the upper switching value and the lower switching value are fixed by a learning process, wherein (a) a first suction channel pressure with the suction gripper closed, and a second suction channel pressure with the suction gripper open or covered by a leaky object are determined, (b) the mean pressure value is formed from the first and second suction channel pressure, (c) the mean pressure value itself, or with the addition of a safety pressure value, is determined to be the lower switching value, and (d) the first suction channel pressure itself, or minus a safety pressure value, is determined to be the upper switching value.

15. The vacuum generating device in accordance with claim 8, wherein the regulating device is embodied for executing the method in accordance with claim 1.

8. A vacuum generating device, having an ejector device which has an inlet connected with an air supply conduit and has a suction opening, to which a suction channel is connected which is, or can be, connected with a suction gripper, furthermore with a pressure detection installation used for detecting the vacuum in the suction channel, and with an electronic regulating device for regulating the vacuum in the suction channel in such a way that the air supply to the inlet is switched off when the vacuum being built up has reached an upper switching value, and is again switched on until the upper switching value has been reached, when the vacuum drops to a lower switching value, wherein the regulating device has regulating time detection means, by means of which the regulating time passing between the switching off of the air supply and either the subsequent restarting or the renewed switching off of the air supply can be detected, and wherein the regulating device furthermore has comparison means, by means of which the detected regulating time can be compared with at least one reference time value stored in memory means, and wherein the regulating device has output means which, as a function of the result of the comparison made by the comparison means, can output an electrical diagnostic signal.

9. The vacuum generating device in accordance with claim 8, wherein a check valve, which opens in the direction toward the suction opening and blocks in the opposite direction, has been inserted into the suction channel.

10. The vacuum generating device in accordance with claim 9, wherein the pressure detection installation is connected to the section of the suction channel extending between the check valve and the suction gripper, or directly to the suction gripper.

11. The vacuum generating device in accordance with claim 8, wherein a control valve has been inserted into the air supply conduit, which can be switched between an open position and a closed position for switching the air supply either on or off, and which can be triggered by the regulating device.

12. The vacuum generating device in accordance with claim 8, wherein a blow-off conduit is connected with the suction channel, into whose course a blow-out valve has been inserted, which can be switched between an open position and a closed position and can be triggered by the regulating device.

13. The vacuum generating device in accordance with claim 8, wherein the memory means are embodied in such a way that several different reference time values can be simultaneously stored in them in such a way that different electrical diagnostic signals can be output by the output means as a function of the result of the comparison.

14. The vacuum generating device in accordance with claim 8, wherein the regulating device has input means serving for the input of data and which can be manually operated.