EP2191148B1 - Vacuum generator device and method for operating the same - Google Patents

Description

The invention relates to a method for operating a vacuum generator device which has an ejector device whose inlet is connected to an air supply channel and the suction side with a suction channel connected to a suction cup, and which has a pressure detecting device for detecting the pressure prevailing in the suction channel, wherein in the suction channel during an evacuation phase, starting from the atmospheric pressure, a sufficient working negative pressure is built up for holding an object through the suction gripper, and during a subsequent aeration phase, a release of the previously sucked-in object causing negative pressure reduction is caused.

The invention further relates to a vacuum generator device having an ejector device which has an inlet connected to an air supply channel and has a suction opening, to which a suction channel is connected, which is connected or connectable to a suction gripper, and with a for detecting the prevailing in the suction channel Pressure-serving pressure detection device, and with control electronics to such control of the pressurization of the suction channel, that during an evacuation phase, starting from the atmospheric pressure for holding an object sufficient vacuum can be built up by the vacuum gripper and, during a subsequent ventilation phase, a releasing of the previously sucked-in object causing negative pressure reduction can be caused.

Such a vacuum generator device as well as a method suitable for its operation of the type mentioned are known from the DE 10 2004 031 924 B4 out. The known vacuum generator device comprises an ejector device whose inlet can be connected via an air supply channel to a compressed air source in order to generate a negative pressure on a suction opening defining a suction side. The negative pressure is also applied to a connected suction channel which is connected or connectable to a suction gripper, by means of which an object to be handled can be held and transported by means of negative pressure. The working vacuum required to hold an object is established in an evacuation phase in which the inlet of the ejector device is supplied with compressed air. For releasing or depositing the previously sucked object, the negative pressure is reduced to an atmospheric pressure or up to an overpressure in a ventilation phase which adjoins the evacuation phase with a time interval. This happens in connection with a shutdown of the ejector.

The known vacuum generator device includes a monitoring device for detecting the number of control operations that are performed between the evacuation phase and the aeration phase to keep the working negative pressure constant within a certain range. This allows some monitoring of the performance of the vacuum generator device. In particular, it is possible to draw conclusions as to whether an increased leakage occurs and consequently whether there are system faults.

From the DE 10 2004 047 853 A1 shows a control device for a suction element, which has a device for generating negative pressure and contains an electronic module which is in operative connection with a separate display and / or operating device. Among other things, the electronic module is used to monitor parameters such as evacuation and ventilation times and transmits the measured parameters to the display and / or operator panel.

The DE 42 29 834 C2 describes a method and apparatus for electrically processing vacuum pressure information, comparing measured to stored pressure values, and then making an error determination.

The US 5,617,898 discloses an array of fluid pressure devices, each having its own electronic control unit to relieve a connected sequencer. The fluid pressure devices may include displays to indicate malfunctions.

The present invention has for its object to propose measures that enable a functional monitoring of a vacuum generating device.

This object is achieved in a method of the type mentioned in that the evacuation in the evacuation phase to build up the working negative pressure evacuation time and / or in the ventilation phase until reaching a release of the previously held article associated ventilation pressure passing ventilation time is detected and compared with at least one predetermined reference time value to produce an electrical diagnostic signal in response to the comparison result, wherein one generates the at least one reference time value within the scope of a teaching process, whereby several work cycles containing at least one evacuation phase and / or at least one aeration phase are processed and the evacuation times (t _E ) and / or ventilation times (t _B ) occurring are determined, wherein the thus determined measured time values are derived, the reference time values, for example by averaging.

The invention is further achieved in a vacuum generating device of the type mentioned above in that the control electronics has time recording means by the evacuation in the evacuation phase to build up the working negative pressure evacuation time and / or in the ventilation phase until reaching a release of the previously recorded object associated ventilation pressure elapsing ventilation time is detected that the control electronics also has comparator means by which the detected evacuation and / or ventilation time with at least one stored in memory means reference time value is comparable, and that the control electronics has output means, depending on the Comparison result of the comparator means can output an electrical diagnostic signal.

Both in the method and in the process according to the vacuum generating device, it is possible to monitor depending on the equipment either only the evacuation phase or only the ventilation phase or simultaneously both the evacuation phase and the aeration phase in their time and by comparison with at least one predetermined reference time value to get a statement about possible malfunctions. The vacuum generating device according to the invention is equipped to perform either only monitoring the evacuation phase or only monitoring the ventilation phase, although it is expediently designed such that both phases can be monitored.

In the method, the reference time value or values are determined by a learning process. This can be done, for example, by alternately operating the vacuum generator device alternately in the evacuation phase and the aeration phase and detecting the evacuation times and ventilation times that occur in the process, which are then evaluated later to determine the respective reference time value. For example, the evaluation may consist in determining an average value. Preferably, the thus determined reference time values can be visualized by the vacuum generator device. It may also be possible to manually change these values to suit individual requirements.

In the evacuation phase, the evacuation time is measured with the help of the pressure detection device connected to the suction channel, which elapses until the build-up of the working negative pressure, expediently starting from the previously applied Atmospheric pressure and in particular beginning with an activation of the ejector device.

In the aeration phase, the aeration time is measured, which elapses until the vacuum prevailing in the suction channel has dropped from the region of the working negative pressure to a venting pressure which is associated with a release of the previously sucked-in article. The aeration pressure used for the time comparison is expediently a pressure in the presence of which it can be assumed that a previously held object was normally released again. The venting pressure may correspond directly to the atmospheric pressure, but is conveniently a slight safety pressure below the atmospheric pressure, which allows for a more accurate measurement because the venting characteristic may be very shallow towards the atmospheric pressure, especially when operating without the ejector pulse. In an operation with ejection pulse, so if the release of the object is supported by a controlled by a blow-off overpressure pulse, the venting pressure may also be an overpressure.

By comparing the time in the evacuation phase, for example, pertinent sources of error can be determined that the system has too high a leakage, that an object does not adhere as intended to the suction pad or that the ejector device is not working. In connection with the ventilation phase can be detected by determining a timeout, for example, that the ejector device has not been disabled or any existing blow-out does not work.

For example, at least one time value based on empirical values can be stored as the reference time value, with which the detected evacuation time and / or aeration time are comparable, in order then to generate an electrical diagnostic signal depending on the result of the comparison, which gives the user indications of the current functional state or directly himself or causes a plurality of measures, for example, the output of an optical and / or acoustic warning message or the direct output of an operable by an external electronic control device electrical signal.

Expediently, the evacuation phase and the aeration phase are each assigned at least one own reference time value.

Advantageous developments of the invention will become apparent from the dependent claims.

Depending on the configuration of the vacuum generator device, it is possible to use the switch-off time of the ejector device and / or the time of an active air injection into the suction channel as starting time for the detection of the ventilation time.

Expediently, a respective diagnostic signal is generated if the detected evacuation time or ventilation time is above the respectively assigned reference time value. The diagnostic signal can be visualized directly on site at the vacuum generator device. If the vacuum generator device is connected to an external electronic control device, a diagnostic signal can also be output to this external control device.

It is possible to classify the detected deviations from the at least one reference time value taking into account the degree of deviation. In this context, a plurality of different reference time values for the evacuation time and / or for the ventilation time can be stored at the same time, wherein the output electrical diagnostic signal depends on which of the stored reference time values corresponds to the respectively detected time. Accordingly, diagnostic signals can be generated at different diagnostic levels where different follow-up actions are taken. Thus, for example, only a warning signal can be emitted at a lower diagnostic level without impairing the function of the vacuum generator device. If the time difference increases and the system thereby enters a higher diagnostic level, drastic measures can be taken, up to a switch to continuous suction operation or a controlled shutdown of the device.

It can be provided that the ejector device remains in operation even after reaching the working negative pressure in order to produce a constant suction effect in the suction channel. In particular, in this case, the working negative pressure used for the time comparison may be below the maximum actual negative pressure actually achievable. Alternatively, there is also the possibility of such a configuration that the ejector device is switched off when a working negative pressure is reached. In this case, a pertinent provision is expediently provided that in time sequence is always evacuated until reaching the desired working negative pressure when the negative pressure falls below a certain threshold. With such Design is associated with a special air-saving effect and consequently an energy-saving effect.

In particular, in the aforementioned embodiment, it is advantageous if in the suction channel, a check valve is turned on, which prevents unwanted degradation of the negative pressure in the located between the check valve and the suction pad system section with the ejector device. The Druckfassungseinruchtung detected here expediently the negative pressure in the extending between the check valve and the suction pad portion of the suction channel.

The aeration phase can be initiated by shutting off the ejector device. If necessary, a blow-off valve can be activated simultaneously with the switching off of the ejector device in order to actively blow pressurized air under atmospheric pressure into the suction channel and to assist in depositing a previously aspirated object by means of an overpressure pulse denominated as a discharge pulse.

Conveniently, the reference time values for the evacuation time and / or the aeration time can be entered by the user of the device itself. For this purpose, the vacuum generator device expediently contains suitable input means.

The control electronics of the vacuum generator device responsible for the evaluation is expediently an internal component of a vacuum generator unit which also contains the ejector device.

In the course of the suction channel, an air filter is expediently switched on. In this context, it is advantageous if monitoring means for monitoring the degree of filter contamination are present. Their function is based in particular on an evaluation of the differential pressure of the prevailing pressure before and after the air filter.

Furthermore, it is possible to monitor any existing electrically actuated valves in their function and to diagnose possible malfunctions in this way. The evaluation is also carried out expediently by the control electronics.

Figur 1

in schematischer Darstellung eine bevorzugte Ausführungsform der erfindungsgemäßen Vakuumerzeugervorrichtung zur Durchführung eines erfindungsgemäßen Verfahrens, und

Figur 2

ein Diagramm, in dem anhand eines während des Handhabens eines Gegenstandes stattfindenden Arbeitszyklus der über die Zeit aufgetragene Unterdruckverlauf im Saugkanal ersichtlich.

In the following we will explain the invention with reference to the accompanying drawings. In this show:

FIG. 1

a schematic representation of a preferred embodiment of the vacuum generator device according to the invention for carrying out a method according to the invention, and

FIG. 2

a diagram in which can be seen on the basis of an occurring during the handling of an object work cycle of the applied over time vacuum curve in the suction channel.

Specifically, the vacuum generator device, indicated generally by reference numeral 1, serves the purpose of temporarily holding articles 5 by means of negative pressure so that they can be repositioned between different locations. It is used, for example, in assembly technology or in the packaging industry. In FIG. 1 is exemplified as an object 5 illustrates a plate-shaped product.

The vacuum generator device 1 contains a vacuum generator unit 2, to which at least one suction gripper 7 is connected. In principle, the vacuum generator device 1 can also be equipped with a plurality of vacuum generator units 2, which can also be combined to form an assembly.

The suction gripper 7 is connected via a suction line 4 to the vacuum generator unit 2. In this case, it can be arranged away from the vacuum generator unit 2. However, it is also possible to arrange the suction gripper 7 directly on the vacuum generator unit 2, so that a rigid assembly is present.

The suction gripper 7 is an example of a suction cup or suction cup. It limits a suction opening 12 having a working opening 8 and can be displaced in such a way that it comes into contact with its work opening 8 ahead of the object 5 to be handled. At the moment of investment the work opening 8 is covered by the article 5 and the suction chamber 12 is closed to the atmosphere.

This condition is indicated by dash-dotted lines in the drawing.

The displacement of the suction pad 7 is done by shifting a device supporting it, which may be the vacuum generator unit 2 itself when it is attached thereto.

On a one or more part of the main housing 3 of the vacuum generator unit 2 is an air supply interface 17, which serves for the supply of compressed air, which is provided by an external compressed air source 18. Furthermore, there is at least one electromechanical communication interface 22 on the main housing 3 for the exchange of electrical signals and for the supply of the electrical energy required for the operation of the electrical components of the vacuum generator unit 2. To the communication interface 22 may in this context an in FIG. 1 schematically indicated external electronic control device 23 are connected.

The vacuum required for gripping an article 5 is generated directly in the vacuum generator unit 2. This is for this purpose equipped with at least one ejector 27, which includes at least one operating according to the ejector principle suction nozzle 26, the inlet 29 is connected via an air supply channel 32 to the air supply interface 17 and thus to the compressed air source 18.

The ejector device 27 also has an outlet 33 leading to the atmosphere, to which a silencer can be connected if required.

Finally, the ejector device 27 has a suction side or suction opening 34, which is connected via a suction channel 35 to the suction chamber 12 of the suction gripper 7.

The suction channel 35 extends with a first channel section 35a inside the main housing 3, wherein it extends from the suction opening 34 to a suction line interface 6 arranged outside the main housing 3. At the latter, the already mentioned suction line 4 is connected, in which the suction channel 35 continues with a channel section 35b to the suction chamber 12.

In the course of the air supply channel 32, an electrically actuated control valve 36 is turned on, which conveniently has a 2/2-way functionality. It may selectively shut off or release the passage of air through the air supply passage 32 to thereby selectively shut off or turn on the air supply to the inlet 29 of the ejector means 27.

Another air supply channel, which is designated for better distinction as a blow-off channel 38 and which is optionally present, also communicates with the air supply interface 17 at one end and is connected to the suction channel 35 at a connection point 28 at the other end. If the outlet channel 38 is present, in turn an electrically actuable control valve is turned on, that is designated for better distinction as a blow-off valve 37. It is preferably of the same type as the already mentioned control valve 36 and may optionally occupy one of two positions in which it either shuts off or releases the passage of air through the exhaust passage 38.

In the course of the suction channel 35, a dotted only indicated check valve 42 may be turned on. It is mainly used when the vacuum generator device 1 is equipped with an air-saving function. While the purge valve 37 with exhaust passage 38 may be present regardless of the presence of a check valve 42, the presence of the check valve 42 presupposes the presence of the purge passage 38 and the associated purge valve 37.

The check valve 42 is oriented so that it allows an air flow from the suction pad 7 toward the ejector 27, but prevented in the opposite direction. In other words, it assumes a shut-off position when the pending on the side of the ejector 27 pressure is absolutely greater than the pending on the side of the suction pad 7 pressure.

The check valve 42 is seated in that portion of the suction channel 35 which extends between the suction port 34 and the connection point 28. As a further feature, the vacuum generator device 1 has a pressure detection device 24. This allows a detection of the pressure prevailing in the suction channel 35 pressure and consequently also the negative pressure prevailing therein. In particular, the pressure detection device 24 is a pressure sensor which converts the pneumatic pressure into electrical pressure signals and feeds them to the vacuum generator unit 2 via a signal line 25, indicated by dashed lines, of an internal electronic control device designated below as control electronics 14.

The pressure detection device 24 is preferably connected directly to the suction channel 35. The designated connection point 30 is located between the possibly existing check valve 42 and the suction pad 7, preferably at the first channel portion 35a. As a result, the negative pressure prevailing in the suction channel 35 is reliably detected even when the ejector device 27 is switched off and the suction opening 34 is connected to the atmosphere via the outlet 33.

The control valve 36 and the possibly existing blow-off valve 37 are expediently solenoid valves, although it is also conceivable to design them as piezo valves. Appropriately, they are of the type "normally closed", so that they occupy the shut-off the associated channel closed position in the electrically non-actuated state. However, they could also be of the "normally open" type, and in particular the control valve 36 can also be designed as a bistable valve (impulse valve).

Their control signals receive the control valve 36 and the blow-off valve 37 via at least one electrical control line 47, 48, by which they are connected to the already mentioned control electronics 14. Via the control lines 47, 48 can also be transmitted from the valves 36, 37 diagnostic signals to the control electronics 14, when the valves 36, 37 are equipped with means for their function monitoring. Such monitoring means may be, for example, means which monitor the switching position of the respective valve. Furthermore, it can be detected by the monitoring means, for example, when an EEPROM is defective, when there is undervoltage or a short circuit, when the solenoid is burned out or when the solenoid does not switch.

In the course of the suction channel 35, an air filter 10 is expediently switched on, which frees the sucked air from impurities. This air filter 10 expediently associated monitoring means 11 which monitor the degree of filter contamination. By way of example, the operating principle of the monitoring means 11 is based on a differential pressure measurement, based on the pressure difference, which is determined by the pressure sensing device 24 arranged on one side of the air filter and a pressure sensor 13 arranged on the other side of the air filter 10. The electrical pressure signals are transmitted via the already mentioned signal line 25 and a further signal line 15 to the control electronics 14 and evaluated by this. The pressure drop across the air filter is a measure of the pollution and can be used to output a signal indicating the need for a filter change.

The control electronics 14 is connected via at least one signal transmission line 43 and expediently also at least one energy transmission line 44 transmitting the electrical energy with the communication interface 22 and can communicate in this way with the external electronic control device 23.

The dot-dash line indicated, sucked object 5 is held by the vacuum generated in response to the evacuation of the suction chamber 12. To deposit it again, the vacuum can be canceled by ventilating the suction chamber 12 again. The latter is done in the embodiment solely by switching off the ejector 27 by shutting off the inlet 29 of the compressed air source 18 by means of the switched into the closed position control valve 36. The suction chamber 12 is then on the suction passage 35 and the suction port 34th and the outlet 33 in the atmosphere and is consequently ventilated.

If the vacuum generator device 1 is equipped with a blow-off valve 37, the ventilation can be assisted by this blow-off valve 37 or carried out alone. A sole venting through the purge valve 37 takes place when the check valve 42 is present. In these cases, pressurized air flows under pressurized air, causing the discharge valve 37 to open at the connection point 28 bypassing the ejector device 27 into the suction channel 35, so that the negative pressure is reduced very rapidly and under certain circumstances even at least for a short time Suction channel 35 prevails.

In the following, with additional description of further functionalities and features of the vacuum generator device 1, a preferred mode of operation of this device will be explained. This is done with reference to the in FIG. 2 shown diagram, which reproduces the time-dependent course of the prevailing in the suction passage 35 at the junction 30 pressure p based on the curve 52 shown in a solid line. The zero point of the ordinate here corresponds to the atmospheric pressure, upwards the negative pressure is plotted.

The diagram refers to a vacuum generator device 1 without a blow-off valve 37 and without a check valve 42.

At any time to prevails in the suction duct 35 atmospheric pressure. The ejector 27 is deactivated because the control valve 36 assumes the closed position.

Any existing blow-out valve 37 would be closed in this case.

In order subsequently to lift an object 5, the suction gripper 7 with its work opening 8 is attached in advance to the object 5 and the ejector device 27 is switched on. The latter is done by switching on the air supply of the inlet 29 by the control valve 36 is switched to the open position. This starts a in FIG. 2 identified evacuation phase 62.

In the evacuation phase 62, a negative pressure gradually builds up in the suction channel 35 in accordance with a first curve section 52a, which increases until it has reached a working negative pressure p _A after the lapse of an evacuation time t _E at the time t ₁ . This working negative pressure p _A is sufficiently high to firmly suck the object to be transported 5 and securely hold.

This is followed by an intermediate phase 63, in which the ejector device 27 is still unchanged during operation, but the negative pressure does not increase any further or at least barely increases because of reaching the power limit of the ejector device 27. During the period of the intermediate phase 63, the negative pressure in the suction channel 35 thus remains substantially at the level of the working negative pressure p _A , with a certain fluctuation range being permissible.

The intermediate phase 63 may be a control phase in a vacuum-saving device 1 equipped with air-saving measures. The vacuum generator device 1 then contains the check valve 42 and the exhaust passage 38 with associated blow-off valve 37. The control phase provides that the control electronics 14, the ejector 27 at the time t ₁ turns off, wherein the negative pressure in the suction channel 35 then still essentially remains, because the check valve 42 prevents degradation of the negative pressure. However, unavoidable leaks will nonetheless lead to a gradual reduction of the negative pressure, with the control electronics 14 re-operating the ejector means 27 when the pressure sensing means 24 detects excessive pressure reduction to a predetermined lower shift value. In the control electronics 14 integrated control means provide here for the desired pressure control and control of the components responsible for it, so that the working vacuum p _{A is maintained} during the intermediate phase 63 within a limited by the lower switching value tolerance band. Since the ejector device 27 is only temporarily in operation in such an intermediate phase functioning as a control phase, compressed air and consequently energy are saved.

The curve 52 has a substantially horizontal course in its second curve section 52b assigned to the intermediate phase 63.

The time t ₂ marks the end of the intermediate phase 63 and at the same time the beginning of a subsequent ventilation phase 64. At the beginning of this ventilation phase 64, the control valve 36 is switched by the control electronics 14 in the closed position, thereby deactivating the ejector 27. This condition is maintained throughout the ventilation phase 64. It has the consequence that the suction line 25 and thus the suction chamber 12 in the manner already mentioned via the outlet 33 of the Ejektoreinrichtung 27 is in communication with the atmosphere and consequently standing at atmospheric pressure air can flow into the suction line 35, which is referred to as aeration ,

As a result of this measure the negative pressure in the suction channel 35 decreases according to the third cam portion 52c from gradually until a time t ₄ again, the atmospheric pressure is reached. This depressurization in the venting phase 64 causes a release of the vacuum in the suction chamber 12 and consequently a release of the previously sucked object 5.

The elapsed between the time t ₂ and the time t ₄ time is in FIG. 2 marked by a double arrow and is referred to as the total aeration time t _GB .

The phases 62, 63, 64 thus define a total of one working cycle A, starting with the suction of an object 5, its subsequent holding and finally depositing the object. The intermediate phase 63 can be used to displace the suction gripper 7 with object 5 fixed thereto, in order to implement the object 5 between two places.

At the time t ₄ , a new evacuation phase can immediately follow again, or else a rest phase, which is used to position the suction gripper 7 closest to the object to be handled.

The control electronics 14 is equipped with time detection means 51 which are capable of detecting both the above-mentioned evacuation time t _E and, independently, an aeration time t _B between the start time t _{2 of} the aeration phase and the attainment of a venting pressure p _B passes. The start time for the detection of the evacuation time t _E is expediently based on the switch-on time of the ejector device 27. In other words, here corresponds to the evacuation time t _{E of} the time that elapses until the suction channel 35th has built up from the atmospheric pressure of the working vacuum p _A.

In the diagram of FIG. 2 is shown as relevant for the time recording working vacuum p _{A of} the maximum generated by the system vacuum. Deviating from this, however, a lower negative pressure, which is already sufficient to hold an object 5, can also be used as the working negative pressure p _A. Such under the maximum producible negative pressure working vacuum p _A is in FIG. 2 dash-dotted and drawn in parentheses. In this case, the time t ₁ would move accordingly (also dash-dotted lines and indicated in parentheses).

As starting time for the detection of the aeration time t _B in the embodiment of coinciding with the time t ₂ shutdown of the ejector 27 is used. If a blow-off valve 37 were present, its switching into the open position and consequently the time of active air injection into the suction channel 35, ie the generation of a discharge pulse, could also be used as the starting time for the detection of the aeration time t _B.

The end time for the measurement of the aeration time t _B may be the already mentioned time t ₄ , in which the pressure in the suction channel 35 has risen to the atmospheric pressure. Here, the aeration pressure p _B then corresponds to the atmospheric pressure and the aeration time t _{B of} the total aeration time t _GB (the values for this are in FIG. 2 in brackets). However, it is in a working without Abwurfimpuls device advantageous than pressure limit (ventilation pressure p _B ) for determining the ventilation time t _B does not use the prevailing at time t ₄ atmospheric pressure, but a order a safety pressure value Δp _s - for example 50mbar - sub-atmospheric pressure. This ventilation pressure p _B modified by a safety factor with regard to the atmospheric pressure naturally already exists at an earlier point in time t ₃ , so that accordingly the ventilation time t _{B to be} detected is shorter than the total ventilation time t _GB .

The reason that it is advantageous to not using it as a ventilation pressure p _B directly to the atmospheric pressure, but the modified by a safety pressure value negative pressure is due to the fact that the third cam section expires 52c relatively flat in its end portion, and thus no exact measured value were available, it would resort to the time t ₄ . Nevertheless, in the exemplary embodiment, the modified aeration pressure in the range of atmospheric pressure, so that it can be concluded upon reaching this modified aeration pressure that a previously sucked object is no longer held.

If the ventilation phase 64 is assisted by a blow-off valve 37, a faster reduction of the negative pressure results, and consequently a considerably steeper third curve section 52c. In such a case, the total aeration time t _GB can be used directly as the time duration t _B to be compared with the reference time value. Alternatively, in such a case, as for the time recording relevant ventilation pressure p _B, for example, also in the suction passage 35 adjusting, overlying the atmospheric pressure over pressure can be used.

The control electronics 14 contains storage means 53, in which both the used for the determination of the evacuation time Working vacuum p _A as well as the used for the determination of the ventilation time ventilation pressure p _{B is} stored. In addition, it contains electronic comparator means 54 in which the negative pressure detected by the pressure detecting means 24 in the suction passage 35 is compared with the stored pressure values to determine the start and end points of the time windows to be measured.

Both the working sub-pressure p _A and the aeration pressure p _B can be preset at the factory. Additionally or alternatively, the control electronics 14 may be equipped with input means 57, which also allow a manual input and / or change of values by the user.

Both during the evacuation phase 62 and during the aeration phase 64, disturbances may occur which impair the desired process. For example, due to leaks occurring, the structure of the desired working negative pressure p _{A may be} delayed or prevented. For example, during the venting phase, a defective spreader valve 36 may erroneously actuate the ejector device 27, so that the venting process may be delayed, if at all. In order to be able to monitor this, the vacuum generator device 1 allows a comparison of the determined times for the evacuation time t _E and the ventilation time t _B with a predetermined reference time value in order to generate an electrical diagnostic signal as a function of the comparison result.

At least one reference time value is stored in the already mentioned storage means 53 for both the evacuation phase 62 and the aeration phase 64, with which the respective measured evacuation time t _E or aeration time t _{B is} compared in the comparator means 54 already mentioned becomes. From the comparison result, an electrical diagnostic signal is generated, which can be output directly or indirectly via output means 55 of the control electronics 14. There is immediate information about the current operating situation.

In particular, a diagnostic signal is generated when the detected time t _E or t _{B is} above the predetermined and stored associated reference time value.

On the basis of the diagnostic signal, for example, an optical and / or acoustic signal can be output. By way of example, the vacuum generator device 1 is equipped for this purpose with output means 55 in the form of a display 55a and a tone generator 55b. In addition, however, the output means 55 also include an output interface 55c via which the diagnostic signal can be output directly as an electrical signal for further processing, in particular to the signal transmission line 43 and via this to the external electronic control device 23.

The reference time values can be permanently programmed from the factory. However, the control electronics 14 of the exemplary embodiment also include manually-operated input means 57 already mentioned, which enable a variable input on site, so that the value can be varied, in particular also as a function of the volume of the connected suction chamber 12.

The vacuum generator device 1 may also have other interface means allowing external input of the various values, in particular those allowing wireless communication.

Preferably, the control electronics 14 also offers the possibility of simultaneously storing a plurality of reference time values in the storage means 53 for both the evacuation time t _E and the aeration time t _B , which are compared with the respectively currently evacuated time t _E or aeration time t _B. Here then it is possible to generate and output different electrical diagnostic signals depending on the duration of the detected times. So you can view and / or process different levels of diagnosis, depending on the intensity of the detected disorder.

The above-mentioned safety pressure value Δp _s is expediently set at the factory.

The exemplary vacuum generator apparatus 1 also offers the possibility to record the reference time values for both the evacuation time t _E and the aeration time t _B in a teach-in mode. This happens in particular in that the device is operated successively in several of the above-mentioned working cycles A, without carrying out the time comparison according to the invention. The herbei measured values for the evacuation time t _E and the ventilation time t _B are then evaluated in each case to form a reference time value. The latter happens in particular in each case by forming an average value from the measured data.

The reference time values determined in this way can be visualized on the display 55a. The user also has the option of changing these values via the input means 57.

Claims (14)

1. Method for the operation of a vacuum generator unit (1) which has an ejector device (27) with an inlet (29) connected to an air supply duct (32), and a suction side (34) connected to a suction passage (35) linked to a suction gripper (7), and having a pressure sensing device (24) for detecting the pressure prevailing in the suction passage (35), wherein in the suction passage (35) during an evacuation phase (62) starting from atmospheric pressure, a working vacuum (p_A) sufficient for an object (5) to be held by the suction gripper (7) is built up, and during a venting phase (64) taking place later in time, a vacuum reduction effecting release of the object (5) previously held by suction is generated, wherein the evacuation time (t_E) elapsing in the evacuation phase (62) until the build-up of the working vacuum (p_A) and/or the venting time (t_B) elapsing in the venting phase (64) until reaching release of the object (5) held previously is recorded and compared with at least one preset reference time value, in order to generate an electrical diagnostic signal based on the result of comparison, characterised in that the reference time value or values is or are generated as part of a teaching process, wherein several operating cycles, each including at least one evacuation phase and/or at least one venting phase are processed, and the evacuation times (t_E) and/or venting times (t_B) occurring here are determined, wherein the reference time values are derived from the measured time values thus determined, for example by averaging.
2. Method according to claim 1, characterised in that a pressure lying in the region of atmospheric pressure is used as venting pressure (p_B).
3. Method according to claim 1 or 2, characterised in that the atmospheric pressure is directly used as venting pressure (p_B).
4. Method according to claim 1 or 2, characterised in that a vacuum lying around a safety pressure value (Δp_s) below atmospheric pressure or an overpressure lying above atmospheric pressure is used as venting pressure (p_B).
5. Method according to any of claims 1 to 4, characterised in that the time elapsing from atmospheric pressure until reaching working vacuum (p_A) is used as evacuation time (t_E).
6. Method according to any of claims 1 to 5, characterised in that the switch-on time of the ejector device (27) is used as the starting time for recording the evacuation time (t_E).
7. Method according to any of claims 1 to 6, characterised in that the switch-off time of the ejector device (27) and/or the time of active air injection into the suction passage (35) are/is used as the starting time for recording the venting time (t_B).
8. Method according to any of claims 1 to 7, characterised in that a diagnostic signal is generated when the recorded time exceeds the preset reference time value.
9. Method according to any of claims 1 to 8, characterised in that an optical and/or an acoustic signal is output on the basis of the diagnostic signal.
10. Method according to any of claims 1 to 9, characterised in that the electrical diagnostic signal is fed to an external electronic control unit (23).
11. Method according to any of claims 1 to 10, characterised in that the recorded time is compared with several different reference time values, in order to generate different electrical diagnostic signals depending on duration.
12. Method according to any of claims 1 to 11, characterised in that the ejector device is switched off when the vacuum in the suction passage has reached the working vacuum (p_A).
13. Method according to any of claims 1 to 12, characterised in that in each case at least one separate reference time value is assigned to the evacuation time (t_E) and the venting time (t_B) as a benchmark.
14. Vacuum generator unit with an ejector device (27), which has an inlet (29) connected to an air supply duct (32), and has a suction orifice (34) at which is connected a suction passage (35) which is or may be connected to a suction gripper (7), also with a pressure sensing device (24) for detecting the prevailing pressure in the suction passage (35), and with control electronics (14) for controlling pressurisation of the suction passage (35) so that, during an evacuation phase (62) starting from atmospheric pressure, a working vacuum (p_A) sufficient for the holding of an object (5) by the suction gripper (7) may be built up, and during a subsequent venting phase (64) a vacuum reduction effecting release of the previously sucked-on object (5) may be generated, wherein the vacuum generator unit is designed to implement the method according to any of claims 1 to 13, and wherein the control electronics (14) have time recording means (51) through which the evacuation time (t_E) elapsing in the evacuation phase (62) until the build-up of the working vacuum (p_A) and/or the venting time (t_B) elapsing in the venting phase (64) until the reaching of a venting pressure (p_B) assigned to the release of the previously held object (5) are or is detected, that the control electronics (14) also have means of comparison (54) through which the recorded evacuation and/or venting times (t_E, t_B) may be compared with at least one reference time value stored in memory means (53), and that the control electronics (14) have output means (55) which, depending on the result of comparison by the means of comparison (54), are able to output an electrical diagnostic signal.

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