US20040197196A1

US20040197196A1 - Vacuum producing device

Info

Publication number: US20040197196A1
Application number: US10/793,093
Authority: US
Inventors: Udo Matheis; Yvonne Krehl
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 2003-04-03
Filing date: 2004-03-04
Publication date: 2004-10-07
Also published as: ATE306619T1; EP1464842A1; EP1464842B1; DE50301356D1

Abstract

A vacuum producing device having at least one ejector unit and a pressure monitoring unit. Since the ejector unit and the pressure monitoring unit are arranged in a common device housing dimensions are extremely compact

Description

BACKGROUND OF THE INVENTION

The invention relates to a vacuum producing device comprising at least one ejector unit, which comprises a nozzle connected with a supply connection, a receiving nozzle placed downstream from the nozzle and an aspiration zone defined in the transition region between the nozzle and the receiving nozzle and connected by way of an aspiration duct with an aspiration connection and furthermore a pressure monitoring unit, which has a pressure sensor connected with the aspiration duct.

THE PRIOR ART.

A vacuum producing device disclosed in the German patent publication 3,818,381 A1 of this type possesses a device housing, which contains an ejector unit and which externally has a plurality of components mounted on it, including a pressure monitoring unit for the pressure in the aspiration duct. The dimensions of this vacuum producing device are relatively large so that it is not really suitable for installation on a suction gripper for handling of objects. The connection with the suction gripper is therefore generally produced using a separate line or pipe.

SHORT SUMMARY OF THE INVENTION

One object of the invention is to provide a compactly designed vacuum producing device.

In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present invention in the case of such a vacuum producing device the ejector unit and the pressure monitoring unit are provided in a common device housing.

The ejector unit and the pressure monitoring unit accordingly possess a common housing so that it is possible to dispense with separate individual housings and the structure may have compact dimensions. The ejector unit serving for the production of a vacuum and the pressure monitoring unit for monitoring the production of vacuum are accordingly integrated in a common housing, the saving in space and weight thus made possible meaning that the device is well suited for the direct integration in suction grippers.

Further advantageous developments of the invention are defined in the claims.

The pressure monitoring unit is preferably accommodated in an accommodating chamber of the device housing termed a sensor accommodating chamber, assembly being substantially simplified owing to having a housing cover. Since the housing cover can be later removed for access to the sensor accommodating chamber, in the case of a defect speedy replacement of the pressure monitoring unit is possible.

The vacuum producing device is extremely convenient as regards fitting since after removal of the housing cover detachable placement of the pressure monitoring unit in the sensor accommodating chamber is possible. Thus the pressure monitoring unit may be firstly installed and then the housing cover may be put in place without the danger of the pressure monitoring unit falling out.

In order to exclude mutual interference the ejector unit and the pressure monitoring unit are preferably separately accommodated on the one hand in an ejector accommodating chamber and on the other hand in a sensor accommodating chamber in the housing of the device. Neither the ejector unit nor the pressure monitoring unit needs a housing of its own, since the housing of the device performs the common housing function for both units.

Preferably the pressure monitoring unit is so designed that an external electronic control means may be connected. For this purpose it possesses an electromechanical interface permitting the connection of such means. The interface is preferably on the same outer side of the device housing as the supply connection of the ejector unit, the same orientation contributing to an improved ease of connection.

A more particularly short overall length is to be achieved, if the ejector unit and the pressure monitoring unit are placed at the same level alongside each other as related to the principal axis of the device housing. It is in this manner that furthermore short paths are produced between the pressure monitoring unit and the aspiration duct, something which improves the response behavior of the pressure sensor.

On the outer side of the device housing and more especially on a removable housing cover preferably optical display means are provided capable of indicating at least one operational state of the pressure monitoring unit, as for example the maintenance of a predetermined vacuum.

Owing to the placement in a common device housing the pressure monitoring unit does not need any separate housing of its own. Preferably it comprises essentially a board, which is fitted with the pressure sensor and suitable evaluating electronic circuitry and preferably furthermore with an electromechanical interface for the connection of an external means. If the evaluating electronic circuitry comprises a micro-controller, settings may be adjusted in a highly convenient manner, for example to set the response thresholds, at which sensor signals are produced in accordance with the needs of the user. The task may also be very easily performed on site, if the vacuum producing device has operating means accessible from the outside. Such operating means may for instance comprise a key extending through the device housing.

Further advantageous developments and convenient forms of the invention will be understood from the following detailed descriptive disclosure of one embodiment thereof in conjunction with the accompanying drawing.

The single figure thereof shows a longitudinal section of a preferred embodiment of the vacuum producing device.

DETAILED ACCOUNT OF WORKING EMBODIMENT OF THE INVENTION.

The vacuum producing device generally referenced [0016] 1 possesses an ejector unit 2 and a pressure monitoring unit 3, which, as considered separately, do not have housings and instead are arranged in common device housing 4 of the vacuum producing device 1. In principle a multiple provision of the device housing 4 with a plurality of ejector units 2 and/or a plurality of pressure monitoring units 3 is possible. In the working embodiment at present the two units 2 and 3 are in the singular, as is considered to be optimum.
The device housing [0017] 4 is provided with two accommodating chambers, which in the following are termed the ejector accommodating chamber 5 and the sensor accommodating chamber 6, the ejector accommodating chamber 5 containing the ejector unit 2 and the sensor accommodating chamber 6 containing the pressure monitoring unit 3.
The [0018] ejector unit 2 comprises a nozzle 7 with a nozzle duct 8 and a receiving nozzle 2 with a receiving nozzle 12 having its receiving nozzle duct 13. In the working embodiment the ejector unit 2 is designed like a cartridge, the nozzle 7 and the receiving nozzle 12 preferably being axially inserted into one another. Generally the ejector unit 2 has an elongated form
The [0019] ejector unit 2 coaxially inserted into the preferably cylindrical ejector accommodating chamber 5. Assembly by plugging is performed through an assembly opening 14 formed as an extension of the ejector accommodating chamber 5, in the device housing 4, in which then a connection device 16 defining a supply connection 15 is secured. The supply connection 15 consequently communicates the with the nozzle 7. The connection device 16 is designed to be able to connect a compressed air line or hose, connected with a source of pressure, in a sealed manner.
The receiving nozzle [0020] 12 is placed downstream from the nozzle 7. It communicates on all sides with the atmosphere, it being connected in the working example with an outlet opening 17 in the device housing 4, which is fitted with a muffler 19.
The nozzle duct [0021] 8 and the nozzle receiving duct 13 are spaced apart, the resulting intermediate space defining an aspiration zone 18. This zone is connected by way of an aspiration duct 22 with an aspiration connection 23, which in the working example is delimited by a further connection device 24 fixed to the housing and which renders possible the connection of a pressure medium line.
The vacuum producing device is more particularly employed to produce a vacuum at a predetermined level in a space, which is to be evacuated, connected with the [0022] aspiration connection 23. The space to be evacuated may more especially be delimited as the interior space of a suction gripper constituted for example by a suction cup or a suction plate, which is part of a vacuum handling instrumentality, with whose aid any desired objects may be held by vacuum and/or conveyed. Since the vacuum producing device 1 has extremely compact dimensions, it may be directly arranged on such a suction gripper so that the suction gripper and the vacuum producing device 1 constitute a single unit.
During operation of such a vacuum handling means the above mentioned suction gripper is applied to the outer face of an object to be handled with the open side of the suction gripper to the fore, following which the above mentioned space is aspirated and evacuated so that there is a vacuum which causes the object to stick to the suction gripper. The following movements of the suction gripper will bring the object into any desired position. In order to release the object, the vacuum in the space is killed. [0023]
The pressure monitoring unit [0024] 3 possesses a pressure sensor 25, which is connected by way of a tapping duct 26 with the aspiration duct 22. The tapping duct 26 extends through a partition 27 separating the ejector accommodating chamber 5 from the sensor accommodating chamber 6, of the device housing 4.
The [0025] pressure sensor 25 is mounted on a board 28, which furthermore carries evaluating electronic circuitry 32. Moreover the board has an electromechanical interface 33 on fixed it, which is connected electrically with the evaluating electronic circuitry 32, such interface 33 being for example designed as a plug device and permitting the connection of an electric cable, not illustrated, by way of which the connection to an external electrical control means may be produced.
The pressure monitoring unit [0026] 3 of the working example is thus composed of the board 28, the pressure sensor 25, the evaluating electronic circuitry 32 and the electromechanical interface 33. With the exception of the electromechanical interface 33, which is accessible from the outside and may protrude a bit past the outer face of the device housing 4, all components of the pressure monitoring unit 3 are accommodated in the interior of the device housing 4 and screened off from the surroundings.
During operation of the vacuum producing device [0027] 1 the pressure sensor 25 measures pressure obtaining in the aspiration duct 22, the evaluating electronic circuitry 32 producing a sensor signal on the basis of the measurements and such signal may be tapped at the electromechanical interface 33. It is in this manner that a control of the ejector unit 2 is possible on the basis of the instantaneous pressure obtaining in the aspiration duct 22. The supply of compressed air to the supply connection 15 may be interrupted for example when and as long as the desired vacuum is present in the aspiration duct 22.
It is an advantage for the evaluating [0028] electronic circuitry 32 to comprise a micro-controller 34. Same permits customized programming and more especially allows the setting of predetermined pressure values, at which the evaluating electronic circuitry 32 produces particular sensor signals. It is accordingly possible for example to set the upper and lower pressure threshold, which define the vacuum to be maintained during operation.
In the working embodiment actuating means [0029] 35 are provided which are accessible from and outside which render possible simple adjustment of the settings of the micro-controller on site. Here it is a question of one or more keys 36, which extend through the wall of the device housing 4 and may be depressed from the outside manually or with a small tool so that same act on the micro-controller 34 by causing a setting operation.
It is furthermore advantageous for optical display means [0030] 37 to be provided on the outer side of the device housing 4 to serve for the display of at least one operational state of the vacuum producing device 1. In the working embodiment the display means 37 comprise a light guide, which extends into the ejector accommodating chamber 5 where it is opposite to at least one light element 38, whose light is passed to the outside to be readily visible.
The [0031] ejector unit 2 and the pressure monitoring unit 3 respectively preferably have an elongated shape. As related to a principal axis 42 of the device housing the two units 2 and 3 in the working example are so placed that they are arranged at the same level parallel to each other. It is in this manner that a compact structure with small longitudinal dimensions of the device housing 4 is made possible.
Furthermore in this manner the tapping [0032] duct 26 may be made extremely short. It opens at the longitudinal side into the ejector accommodating chamber 5 so that the vacuum is measured in the direct vicinity of the aspiration zone 18 and hence short measurement paths and a correspondingly high accuracy of measurement are achieved.
At the other end the tapping [0033] duct 26 opens into a recess 43 in the partition 27 belonging to the sensor accommodating chamber 3, into which the pressure sensors 25 extends through an intermediate seal 44. The recess 43 is consequently sealed off from the remaining part of the sensor accommodating chamber 6, in which the pressure monitoring unit 3 is located.
The two [0034] units 2 and 3 are both placed in a principal plane, coinciding with the principal axis 42, of the device housing 4 such plane being identical to the plane of the drawing. Considered at a right angle to this the vacuum producing device is very narrow. There is more especially a provision such that the supply connection 15, the aspiration connection 13 and the electromechanical interface 33 lie in this principal plane and are aligned in the direction of extent of the principal plane.
In the working embodiment furthermore the [0035] lectromechanical interface 33 and the supply connection 15 are arranged in a common, front outer side 45 of the device housing 4 and are identically orientated and aligned with the principal axis 42.
The [0036] aspiration connection 23 in the said principal plane is directed to the side. The outlet opening 17, also lying in the principal plane, is preferably located on the rear outer side 46 opposite the front outer side 45, of the device housing 4.
If the [0037] ejector unit 2 is replaced by a differently designed structural shape, the aspiration connection 23 and the outlet opening 17 may be interchanged as well.
One or more through [0038] holes 47 extend through the device housing 4 at a right angle to the principal plane to receive screws, for example, serving to fix the vacuum producing device 1 on some suitable support structure, as for example on a suction gripper.
While the [0039] ejector unit 2 is able to be installed and removed through the above mentioned assembly opening 14, the installation and removal of the pressure monitoring unit 3 takes place through an opening 48 in the housing leading into the sensor accommodating chamber 6, such opening 48 being shut by a housing cover, which may be opened. By way of an attachment screw 53 the housing cover 52 is fixed to the remaining housing component 54 more especially in a detachable manner so that when required it may be removed in order to gain access to the sensor accommodating chamber 6. Instead of an attachment screw 53 other attachment means may be employed, as for example a detent connection between the housing cover 52 and the remaining housing component 54.
Further attachment means [0040] 55 render possible securing the pressure monitoring unit 3 even after removal of the housing cover in the desired position of installation. In the working embodiment the further attachment means 55 comprise the pressure sensor 25, the annular sensor 44 surrounding it, and the recess 43. These components may be plugged into each other so that the resulting friction holds the pressure monitoring unit 3 on the remaining housing component 54 temporarily. Then the housing cover 52 may be readily put in position and secured.
The setting means [0041] 35 and the display means 37 are preferably arranged on the removable housing cover 52.
The [0042] housing cover 52 extends preferably along the elongated sensor accommodating chamber 6 so that when the cover 52 is removed the latter chamber is accessible along its full length and accordingly the pressure monitoring unit 3 may be inserted in the transverse direction.
Since the housing of the [0043] ejector unit 2 and of the pressure monitoring unit 3 are respectively constituted directly by the common device housing 4, there is no need for separate housings for the two units and an economic and extremely compact structure of the vacuum producing device 1 is possible.

Claims

1. A vacuum producing device comprising at least one ejector unit, which comprises a nozzle connected with a supply connection, a receiving nozzle placed downstream from the nozzle and an aspiration zone defined in the transition region between the nozzle and the receiving nozzle and connected by way of an aspiration duct with an aspiration connection and furthermore a pressure monitoring unit, which has a pressure sensor connected with the aspiration duct, wherein the ejector unit and the pressure monitoring unit are provided in a common device housing.

2. The vacuum producing device as set forth in claim 1, wherein the pressure monitoring unit is arranged in a sensor accommodating chamber shut off by a housing cover.

3. The vacuum producing device as set forth in claim 2, wherein the housing cover is able to be removed for gaining access to the sensor accommodating chamber.

4. The vacuum producing device as set forth in claim 2, comprising attachment means for detachable holding in place of the pressure monitoring unit in the sensor accommodating chamber when the housing cover is taken off.

5. The vacuum producing device as set forth in claim 1, wherein the ejector unit and the pressure monitoring unit are arranged separately in an ejector accommodating chamber of the device housing.

6. The vacuum producing device as set forth in claim 1, wherein the pressure monitoring unit is provided with an electromechanical interface accessible from the outside and rendering possible the connection of an external means.

7. The vacuum producing device as set forth in claim 6, wherein the electromechanical interface of the pressure monitoring unit and the supply connection of the ejector unit are provided on a common outer side of the device housing and are orientated in the same direction.

8. The vacuum producing device as set forth in claim 1, wherein the device housing has a principal axis and the ejector unit and the pressure monitoring unit each have an elongated shape and with respect to the direction of the principal axis are placed at the same level in a manner parallel to one another.

9. The vacuum producing device as set forth in claim 1, comprising display means on the outer side of the device housing for the display of at least one operational state.

10. The vacuum producing device as set forth in claim 1, wherein tapping of pressure for the pressure sensor is arranged to take place in an ejector accommodating chamber containing the ejector unit.

11. The vacuum producing device as set forth in claim 1, wherein the pressure monitoring unit comprises a circuit board bearing a pressure sensor and evaluating electronic circuitry.

12. The vacuum producing device as set forth in claim 11, wherein the evaluating electronic circuitry comprises a micro-controller.

13. The vacuum producing device as set forth in claim 12, comprising externally accessible actuating means for changing the settings of the micro-controller.

14. The vacuum producing device as set forth in claim 13, wherein the actuate means comprise at least one key extending through the wall of the device housing.