EP2943295B1 - Blowing device and method for the operation thereof - Google Patents

Description

• mindestens einer Anschlussöffnung für das gasförmige oder flüssige Medium,
• sowie mehreren Anblasdüsen, über welche das gasförmige oder flüssige Medium kontrolliert auf vorbestimmte Einzelstücke des Materialstroms blasbar ist,
• sowie den Anblasdüsen zugeordneten Ventilen, vorzugsweise Magnetventilen, durch welche der Anblasvorgang ausgelöst bzw. gestoppt werden kann und die am oder zumindest teilweise im Gehäuse angeordnet sind,
• sowie einem Strömungskanal zwischen jeder Anblasdüse und dem Ventilsitz des einer Anblasdüse zugeordneten Ventils.

The present invention relates to a device for blowing over a free fall distance or a link belt conveyed individual pieces of a stream of material with a gaseous or liquid medium, comprising a housing with

• at least one connection opening for the gaseous or liquid medium,
• as well as a plurality of blowing nozzles, via which the gaseous or liquid medium can be blown in a controlled manner onto predetermined individual pieces of the material stream,
• and valves assigned to the blowing nozzles, preferably solenoid valves, by means of which the blowing process can be triggered or stopped and which are arranged on or at least partially in the housing,
• and a flow passage between each blowing nozzle and the valve seat of the valve associated with a blowing nozzle.

Such devices are approximately from the AT 8634 U1 known and come in sorting machines for transparent and non-transparent bulk materials such as metals, plastics, rocks and glass, paper or cardboard used. They work preferably by means of optical or inductive transmitter and receiver units and serve to remove foreign matter located in the material flow from the material flow or to convey different types of the material of the material flow into different containers.

The transmitter units consist for example of light rays emitting light sources, preferably diode light sources, which are bundled in the receiver unit via a lens system on a photocell. However, embodiments are also known in which color cameras are used as receiver units and as Light sources conventional light sources such as fluorescent tubes act.

Both transmitter and receiver units are connected to a central processing unit, which processes the incoming data and, due to the intensity of the incident on the receiver unit and radiated by the transmitter units light beams to detect location, size and type of individual pieces located in the material flow.

Subsequently, the sorting of the individual pieces is carried out in dependence on the successful detection of the individual pieces in the material flow. This takes place in a manner known per se by blowing the individual pieces by means of a gaseous or liquid medium, for example compressed air or water, during their free fall or during their transport on a link belt through the gaps of the link belt, whereby these from their trajectory or . Are deflected from the material flow lying on the link belt in a designated container.

In known sorting machines serves as a blowing the Anblasdüsen and leading to the Anblasdüsen flow channels containing component to which commercial acquirable solenoid valves are coupled, preferably screwed, whereby the Ventilauslassöffnung or the Ventilauslassöffnungen are connected to corresponding component provided on the input openings of the device to establish a connection to the blowing nozzles. A conventional solenoid valve usually consists of a valve stem and a return spring, to reset the valve stem and an electromagnet, which causes the opening movement of the valve stem. Return spring and electromagnet are due to the operation of the Valve, each seen on different sides of the valve stem with respect to the axis thereof, arranged.

In order to achieve a high sorting accuracy, as many solenoid valves as possible are arranged on the desired sorting width (width of the free-fall path or the link belt). In addition to the number of solenoid valves but also the shortest possible switching time and the shortest possible distance of the valve seat to the exhaust nozzle, more precisely to the nozzle mouth, are crucial. Therefore, about commercially available quick-acting solenoid valves are used. These can be equipped with a quick-switching function (based on electrical overexcitation) and with lubrication checked for food safety in order to shorten the reaction time. In order to obtain as precise a compressed air surge as possible, high flow velocities and small volumes flowed through are required. When switching off the solenoid valve, the fastest possible pressure drop in the flow channel is desired, which quickly stops the flow.

If the control electronics opens the solenoid valve, a compressed air flow builds up from the valve seat in the flow channel in the direction of the nozzle mouth. Due to the abrupt closing when the solenoid valve is switched off, a vacuum or negative pressure is generated in the flow channel due to the inertia of the air column. As a result, small dust particles are sucked into the flow channel. If they reach the valve stem of the solenoid valve, they cause additional friction and, as a result, increased wear. This reduces the life of the solenoid valves.

Although this could be reduced or even prevented by slower closing times of the solenoid valve or a greater distance between the valve seat and the nozzle mouth, however, both alternatives cause a slower pressure drop in the flow channel and thus not one exact end of the compressed air flow, which has a negative effect on the sorting.

The DE 10 2008 050 907 A1 discloses the preamble of claim 1.

The DE 10 2008 050 907 A1 shows two variants of dust protection means between the outlet opening of the exhaust nozzles and the valves of a blower: a first variant comprises a cavity, seen from each of the exhaust nozzles in the direction of fall, the nozzle subsequent to the nozzle supply line extends to the bottom of the cavity. At a distance above the ground a Querzuführleitung opens into the Düsenzuführleitung. This ensures that penetrating dust particles do not penetrate to the valves, but deposit below the mouth of Querzuführleitung in the cavity. This first variant has the disadvantage that the nozzle supply line adjoining the nozzle must always be arranged vertically in order to deposit dust particles that penetrate. In addition, increases by the distance of the transverse feed bore to the bottom of the cavity, the volume of the nozzle supply line and the space required.

The second variant of dustproofing the DE 10 2008 050 907 A1 comprises for each exhaust nozzle a valve-free bypass line, via the compressed air when the main body of the blower permanently compressed air flows to the exhaust nozzles. As a result, compressed air continuously exits from the exhaust nozzles, whereby dust particles can be prevented from entering the exhaust nozzle. The bypass lines are open in this variant during the entire Druckluftbeaufschlagung, which constantly lost compressed air.

It is therefore an object of the present invention to provide a device of the type mentioned, which prevents the suction of dust particles in the flow channel after the shooting of the solenoid valve, without slower closing times of the solenoid valve or a greater distance between the valve seat and the nozzle mouth, and also without limiting the direction of how the nozzle supply lines must be arranged in the operating state of the device and without bypass lines with continuous Druckluftbedeaufschlagung.

This is achieved by the characterizing features of claim 1 according to the invention. Accordingly, it is provided that in each case at least one connecting channel branches off from a plurality of flow channels, which opens into at least one pressure reservoir common to the connecting channels, which is sealed gastight and / or liquid-tight except for the connecting channels and the pressure reservoir communicates only through the connecting channels through that medium through which the Anblasdüsen associated valves, preferably solenoid valves, has flowed, acted upon, can.

This ensures that the so-called backflow compensation, ie the avoidance of the suction of dust particles in the flow channel, is activated only in the time in which the valves of the device (the device is usually designed as a block) are active. During the break times, the valves are closed and there is no loss of compressed air, which makes it - in comparison to DE 10 2008 050 907 A1 - comes to a reduction in compressed air consumption. The compressed air for the backflow compensation is diverted from the exhaust air of the active valves via a - designed as a throttle bore - connecting channel and passed into the - executed as a cross bore - common pressure reservoir. From there it is sucked back into an adjacent flow channel or, after completion of a valve opening, back into the same flow channel (ie into the same or an adjacent blow-out bore). The spatial orientation of the flow channel section in front of the Anblasdüse plays no role.

In other words, the pressure reservoir, the connection channels and the flow channels are formed so that when opening one or more valves medium from each open valve through the associated flow channel and the one or more branching from this flow channel connecting channels flows into the pressure reservoir, while the same medium from the pressure reservoir flows through one or more other connecting channels in those or those flow channels whose valve is closed.

Preferably, exactly one connection channel will branch off from each flow channel of a device according to the invention and all flow channels of a device will have a connection channel. But it is also conceivable that only some flow channels have such a connection channel. Independently of this, it would also be possible to provide a plurality of connection channels per flow channel, which lead into the same pressure reservoir. Or it could lead to different connection channels of a flow channel in different pressure reservoirs.

Through the connection of the individual flow channels via connection channels and a common pressure reservoir, a compressed air partial flow is branched off from those flow channels which are currently exposed to compressed air and passed into the pressure reservoir, which thus serves as a compressed air reservoir. If the solenoid valve of the previously acted upon with compressed air flow channels closed, is sucked by the resulting vacuum or negative pressure pure compressed air from the pressure reservoir through the connecting channels and no longer contaminated ambient air through the nozzle mouth. This increases the service life of the solenoid valves.

Since when using the inventive device for sorting the solenoid valves often switch, it is also ensured that the pressure reservoir repeatedly with compressed air is replenished. From a certain on-time of the solenoid valves per minute, the saturation is reached, the pressure in the pressure reservoir will not increase, due to the back pressure flows less medium from the flow channels in the connecting channels, the volume of the branched medium thus decreases.

There is no additional control effort for the operation of the connection channels or the pressure reservoir necessary, at standstill, the pressure reservoir consumes no compressed air, it is only in valve activity in operation. There must be - due to the lack of moving parts - no maintenance of the connecting channels or the pressure reservoir.

A good effect according to the invention is provided if the cross-sectional area of the connecting channels is 5-10%, in particular about 6.5%, of the cross-sectional area of the nozzle mouth of the blowing nozzles. As a result, less than 10% of the air that passes through the solenoid valve in the flow channel, in the connecting channel and in the pressure reservoir.

The volume of the pressure reservoir is usually greater than the common volume of all flow channels. If the pressure reservoir is designed as a simple bore, then its diameter is usually larger by a multiple than the diameter of a flow channel.

It can be provided that the flow channel causes a, in particular only a single, deflection of the gaseous medium and the connecting channel branches off in the region of this deflection of the flow channel, in particular in the direction of the medium before the deflection (relative to the flow direction of the medium in the operating state, if it flows from the valves to the blowing nozzles). For example, it may be provided that the flow channel consists of a first straight section, starting at the valve seat of the valve, and a second straight section, which in an angle between 0 and 180 °, in particular at an angle of 90 °, to the first section, and the longitudinal axis of the connecting channel coincides with the longitudinal axis of the first straight section. That is, the first straight portion begins at the valve seat, follows the longitudinal axis of the valve seat and ends at the deflection. The second section begins at the deflection and ends at the nozzle mouth of the blowing nozzle. The deflection is designed so that the second section in the region of the deflection at least over the longitudinal axis of the valve seat or the first section.

If the longitudinal axis of the connecting channel coincides with the longitudinal axis of the first straight section, that is, the connecting channel in the region of the deflection so to speak arranged opposite the valve, this has the advantage that there is the greatest negative pressure when the valve is closed. After closing the valve, therefore, the medium can flow from the pressure reservoir via the connecting channel directly to this point where the greatest negative pressure prevails.

In this preferred embodiment with an angle of 90 ° between the first and second sections of the flow channel then the valve stem of the valve, if this is screwed approximately into the device, substantially perpendicular to the Anblasdüse or to the second portion of the flow channel. Otherwise, the valve stem of the valve will enclose an acute angle with the axis of the blowing nozzle or with the second portion of the flow channel.

The design that the pressure reservoir next to the connecting channels has a closable connection for the supply of gaseous or liquid medium could be used to fill the pressure reservoir from outside the device with medium and to ensure that the pressure in the pressure reservoir is always high enough. However, one would do without the inventive advantage that no additional supply of medium, such as compressed air, is necessary.

The blowing device according to the invention can be operated with compressed air.

Preferably, each valve can be assigned a Anblasdüse. This variant makes it possible, given the number of blowing nozzles, to achieve the highest resolution or blowing precision. But it would also be possible for a valve to supply several blowing nozzles. By controlling multiple Anblasdüsen by means of a valve a simplified control is possible.

A particularly compact design for a device according to the invention is achieved when the Anblasdüsen, the valve stem including the valve seat, the at least one connection port, the flow channels, the connecting channels and the pressure reservoir are housed in a single housing. The housing may have approximately the shape of a cuboid.

Another embodiment of a device according to the invention provides that the Anblasdüsen, the at least one port, the flow channels, the connecting channels and the pressure reservoir are housed in a single housing, while the valve stem and valve seat of the valves are outside the housing.

The pressure reservoir can most easily be designed as a cylindrical bore, but other shapes and production methods of a cavity can also be used.

The subject invention is basically used in all generic devices for blowing (valve blocks).

A possible method for operating a device according to the invention provides that the pressure reservoir is acted upon via the connecting channels by that medium which has flowed through the valves associated with the blowing nozzles, preferably solenoid valves. It is not excluded that the pressure reservoir at least temporarily additional medium is fed through a - different from the connection channels - closable connection.

However, according to the invention, the method is designed so that the pressure reservoir is closed gas-tight and / or liquid-tight except for the connecting channels and the pressure reservoir is acted upon only via the connecting channels by that medium which has flowed through the valves associated with the blowing nozzles, preferably solenoid valves.

Fig. 1

eine perspektivische Ansicht einer erfindungsgemäßen Anblasvorrichtung mit außerhalb des Gehäuses angeordneten Ventilen,

Fig. 2

eine Schnittansicht einer erfindungsgemäßen Anblasvorrichtung nach Fig. 1,

Fig. 3

eine perspektivische Ansicht einer weiteren erfindungsgemäßen Anblasvorrichtung mit innerhalb des Gehäuses angeordneten Ventilen.

Following is now a detailed description of the invention with reference to drawings. It shows

Fig. 1

a perspective view of a blowing device according to the invention with arranged outside the housing valves,

Fig. 2

a sectional view of a blowing device according to the invention according to Fig. 1 .

Fig. 3

a perspective view of another blowing device according to the invention with valves arranged within the housing.

Fig. 1 shows a Anblasvorrichtung invention, consisting of a cuboid housing 12 whose walls are transparent here in order to recognize the arrangement of the individual elements inside. The housing 12 is preferably made of aluminum. Alternative materials However, such as steel, stainless steel, brass or plastic can also be used.

In this case, compressed air is introduced into the housing 12 via the connection opening 1, which opens into a supply chamber 2, which extends in the housing transversely to all - in this case twelve - solenoid valves 3. Six solenoid valves 3 are arranged on the top of the housing, six on the back. The valve seat and the valve stem of the solenoid valves 3 are located outside the housing here. The direction of movement of the valve stem may, for example, be parallel to the surface of the housing 12, ie normal to the subsequent flow channel 4 located in the housing 12. However, the direction of movement of the valve stem may also be normal to the surface of the housing 12, ie in the direction of the adjoining flow channel 4 ,

Through the supply chamber 2, the compressed air is evenly distributed to all the solenoid valves 3 by each a compressed air line 11 leads from the supply chamber 2 to a solenoid valve 3. This can open, whereby compressed air enters the respective flow channel 4.

One type of flow channels 4, which are assigned to the solenoid valves 3 on the back, consists of a straight first section (here perpendicularly oriented from back to front), which at a right angle into a straight second section (here down) passes to into a Anblasdüse 7 (not visible here) to open at the bottom of the housing 12. In continuation of the straight first section is in each case a connecting channel 5 in the all twelve flow channels 4 common pressure reservoir 6 via.

The second type of flow channels 4, which are assigned to the solenoid valves 3 on the top, is just (here from top to bottom) in the Anblasdüse 7 on the underside of the housing 12, about in the last quarter a connecting channel 5 branches off at right angles into the common pressure reservoir 6.

At the pressure reservoir 6 close for manufacturing reasons, six holes 10, which are irrelevant to the invention and are sealed by means of threaded pins or metal balls, so do not represent a connection to the outside space.

The Anblasdüsen 7 can be designed as its own, screwed about, components, but they can also be easily realized by the last part of the flow channel 4 or by its exit from the housing, see Fig. 2 ,

In Fig. 3 a housing 12 is provided with eight solenoid valves 3, the electromagnets 3 are arranged at the top of the housing. The electromagnets are screwed into the housing 12 and actuate the valve stem, which move in the vertical direction (normal to the surface of the housing 12), but are not visible here. The valve seat is provided in the housing 12. The straight flow channels 4 here form an acute angle with the direction of movement of the valve stem. It is provided for all flow channels 4, a common pressure reservoir 6 in the form of a bore, which also runs normal to the flow channels 4, almost over the entire length of the housing 12. At the pressure reservoir 6 close for manufacturing reasons, holes 10, which are tightly closed in this embodiment by means of threaded pins or metal balls, so do not represent a connection with the outside space. Thus, also in Fig. 3 (as in Fig. 1 ), the pressure reservoir 6 are acted upon only via the connecting channels 5 with gaseous or liquid medium, or can escape only via the connecting channels 5 gaseous or liquid medium from the pressure reservoir 6.

• Über die Anschlussöffnung 1 wird das Arbeitsmedium in das Gehäuse geleitet, wo es zuerst in die Versorgungskammer 2 gelangt, bis es den jeweiligen Ventilsitz der einzelnen Magnetventile 3 erreicht hat. Diese Ventile sind zu diesem Zeitpunkt geschlossen, d.h. jeder Ventilstössel schließt dicht mit dem Ventilsitz ab. In Abhängigkeit von einem Steuersignal einer zentralen Recheneinheit, welches wiederum auf einer Detektion von auszusortierenden Einzelstücken in dem Materialstrom basiert, werden die Elektromagnete aktiviert, wodurch sich die Ventilstössel bewegen und das Ventil öffnet. Das gasförmige Arbeitsmedium kann nun in die entsprechenden Strömungskanäle 4 strömen und aus deren Enden bzw. über die Anblasdüsen 7 austreten.

The operation of the blowing device according to the invention is as follows:

• About the connection opening 1, the working fluid is passed into the housing, where it first enters the supply chamber 2 until it has reached the respective valve seat of the individual solenoid valves 3. These valves are closed at this time, ie each valve stem closes tightly with the valve seat. Depending on a control signal of a central processing unit, which in turn is based on a detection of individual pieces to be sorted out in the material flow, the electromagnets are activated, whereby the valve tappets move and the valve opens. The gaseous working medium can now flow into the corresponding flow channels 4 and exit from their ends or via the blowing nozzles 7.

A compressed air partial flow is diverted from those flow channels 4, which are currently subjected to compressed air, and fed into the pressure reservoir 6, which thus serves as a compressed air reservoir. If the solenoid valve 3 of the previously acted upon with compressed air flow channels 4, is sucked by the resulting vacuum or negative pressure pure compressed air from the pressure reservoir 6 through the connecting channel 5 and no longer contaminated ambient air through the nozzle mouth of the Anblasdüse 7. From a certain on-time The saturation of the solenoid valves 3 per minute is reached, the pressure in the pressure reservoir 6 will not increase any further, because of the counterpressure less medium flows from the flow channels 4 into the connection channels 5, the volume of the branched medium therefore drops.

It is accepted that a part of the compressed air escapes from the pressure reservoir 6 via those connecting channels 5, which are just not acted upon by their flow channels 4 with compressed air.

LIST OF REFERENCE NUMBERS

1

port opening

2

Versorgungskammer

3

Valve (solenoid valve)

4

flow channel

5

connecting channel

6

pressure reservoir

7

Anblasdüse

8th

first section of the flow channel 4

9

second section of the flow channel 4

10

Holes for the pressure reservoir. 6

11

Compressed air line to valve 3

12

casing

Claims (9)

1. A device for blowing individual pieces of a material flow using a gaseous or fluid medium conveyed over a gravity section or link belt comprising a housing (12) having

   - at least one connection opening (1) for the gaseous or fluid medium, - and multiple air jet nozzles (7), through which the gaseous or fluid medium can be blown at predetermined individual pieces of the material flow in a controlled manner,
   and valves assigned to the air jet nozzles (7), preferably solenoid valves (3), by means of which the blowing process can be initiated or stopped and which are arranged an or at least partially within the housing,

   - and a flow channel (4) between each air jet nozzle (7) and the valve seat of the valve (3) allocated to an air jet nozzle (7), with at least one connecting channel (5) branching off from each of a plurality of flow channels (4) and discharging into at least one pressure reservoir (6) common to the connecting channels (5) characterised in that,
   the pressure reservoir (6), apart from the connecting channels (5), is sealed in a gastight and/or liquid-proof manner and the pressure reservoir (6) can only be impinged upon by the medium flowing through the valves, preferably solenoid valves (3), corresponding to the air jet nozzles (7) via the connecting channels (5).
2. Device according to Claim 1 characterised in that the cross-sectional surface of the connecting channels (5) is 5-10%, particularly 6.5%, of the cross-sectional profile of the nozzle mouth of the jet nozzles (7).
3. Device according to either Claim 1 or 2, characterised in that the flow channel (4) effects a diversion, in particular only a single one, of the gaseous or fluid medium and the connecting channel (5) in the area of this diversion branches off from the flow channel, in particular in the direction of the medium ahead of the diversion.
4. Device in accordance with Claim 3, characterised in that the flow channel (4) consists of a first straight section (8), starting at the seat of the valve (3), as well as of a second straight section (9) connecting to the first section (8) at an angle of between 0 and 180 degrees, in particular an angle of 90 degrees, with the longitudinal axis of the connecting channel (5) coinciding with the longitudinal axis of the first straight section (8).
5. Device according to any one of Claims 1 to 4, characterised in that the gaseous/liquid medium is compressed air/water.
6. Device according to any one of Claims 1 to 5, characterised in that one air jet nozzle (7) corresponds to each valve (3).
7. Device according to any one of Claims 1 to 6, characterised in that the air jet nozzles (7), the valve plunger including valve seat, the minimum of one connection opening (1), the flow channels (4), the connecting channels (5) and the pressure (11) reservoir (6) are accommodated in a single housing (12).
8. Device according to any one of Claims 1 to 7, characterised in that the air jet nozzles (7), the minimum of one connection opening (1), the flow channels (4), the connecting channels (5) and the pressure reservoir (6) are accommodated in a single housing, while the valve plunger including the valve seat of the valves (3) are located outside the housing.
9. Method for operating a device for blowing air according to any one of Claims 1 to 8, characterised in that the pressure reservoir (6) can only be impinged upon by the medium flowing through the valves, preferably solenoid valves (3), corresponding to the air jet nozzles (7) via the connecting channels (5), and the pressure reservoir (6), apart from the connecting channels (5), is sealed in a gastight and/or liquid-proof manner.

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