WO2009054732A1

WO2009054732A1 - A coanda ej ector

Info

Publication number: WO2009054732A1
Application number: PCT/NO2008/000378
Authority: WO
Inventors: Terje Lien
Original assignee: Ntnu Technology Transfer As
Priority date: 2007-10-26
Filing date: 2008-10-24
Publication date: 2009-04-30
Also published as: NO20075444L; NO327504B1

Abstract

Ejector for fluids, comprising : - one or more primary fluid inlets (2) for primary fluid (1) to a distribution chamber (4); - one or more secondary fluid inlets (81) for secondary fluid (7) to a secondary fluid chamber (8) with an outlet (86) to a longitudinal outlet channel (6) with first and second wal l (61, 6I1 ); - a first plate (14) covering a first end of said secondary fluid chamber (8) and forming a third wall in said outlet channel (6); - a second plate (13) covering a second, oppositely arranged end of said secondary fluid chamber (8) and forming a fourth wall in said outlet channel (6); - a linear Coanda nozzl e (5) from said distribution chamber (4) leading into said outlet (86) with an angle relative to said outlet channel' s (6) direction, extending in the full height of said secondary fluid chamber' s (6) height between said second plate (13) and said first plate (14); said coanda-nozzle (5) arranged for diverting primary fluid (1) to said outlet channel (6) and create suction effect at secondary fluid inlet (81).

Description

A COANDA EJECTOR

Introduction

The invention relates to an ejector for fluids, of which said fluids may be gas or liquid. More specifically the invention relates to an ejector in which primary air is conducted in and which is blown through a slit and in which the air is deviated along a guide wall according to the so-called Coanda effect, the guide wall being flush with an outlet, so as for the primary air to accelerate secondary air along from a secondary air chamber and produces an underpressure in the secondary fluid chamber, which may be provided with a vacuum suction surface. The invention may be applied among other things as a vacuum gripping device for fragile or porous devices such as paper, textile, skin, fish- and meat filets and other devices having a low weight, high porosity and little bending stiffness.

Background art

The so-called Coanda effect makes an airstream which passes a cylinder surface to be deviated to some degree along the cylinder surface. US3881523 to Paton describes a weaving machine. Paton describes in col. 3, lines 32-47and with reference to Fig. 3 how the running thread may be deviated in a lateral direction at an edge by means of the Coanda effect.

Cylindrical Coanda effect pumps exist in which secondary air is guided through a sleeve,^' se Fig. 8 on background art, in which a supply for pressurized air runs into a distribution channel in the periphery of the sleeve, and in which a slit ends up in an arc-shaped, circular surface which continues to constitute the sleeve's inner surface towards the outlet's direction, will lead the primary air with high speed along the sleeve's inner surface, and thus accelerate secondary air along. Such cylindrical Coanda effect pumps are capable for accelerating air to high speed, but has a small efficiency and form a relatively weak underpressure at the secondary fluid inlet as compared to other vacuum pumps.

US3316657 describes an apparatus for drying a continuous paper band comprising an endless air permeable band which is moveable with the paper band and arranged for pressing the paper band towards drying devices in the apparatus, and a linear Coanda nozzle extending essentially in the direction of the width of the paper band near a surface in this, in a desired position along the path of the band where it is not in contact with the paper band, where the linear nozzle is oriented so with respect to the band that the gas flow induced by the nozzle will arise in the gas mass near the same side of the surface of the surface of the band as the nozzle is situated, and converge with the bans in a sharp angle with the direction of movement of the band, and will pass essentially through the band to the opposite side of the band relative to the nozzle.

US4332529 "Jet diffuser ejector" describes a Coanda ejector for increasing the thrust improvement with a very short length of the ejector. The ejector is provided with primary injection nozzles arranged in a predetermined spatial relationship with the inlet portion of the ejector and in a predetermined angle with respect to the thrust axis of the ejector. The ejector may comprise a diffusion part and downstream diffusion parts with an axially directed diffusion ray arranged between the diffusion parts.

GB1512785 "Ejectors" describes an extended linear Coanda-ejector having an external linear Coanda nozzle. GB1512785 is arranged particularly to move air, and comprises an extended body formed as an extrusion and an extended lid portion attached to the main body, in which the main body and the lid part are shaped so as for defining an air slit for releasing the primary air between an edge of the main body and an edge in the lid part in communication with a primary air chamber inside the main body..

GB791463 describes a device for inducing a stream of cooling air for internal combustion machines, particularly jet engines with a gas turbine.

US5093059 "method for transport of a homogenous mixture of cut fibres" describes an apparatus in which the fibres remain in a homogenously mixed condition during their transport from a cutting pistol to a workpiece by means of two transvector-apparatuses placed in series with a channel attached between those two apparati. The two apparati are Coanda-ejectors which accelerate the air in the inlet and outlet.

US2004/0091350 . "Fluid activation for improved diffuser effect" describes a diffuser having an aperture along the inner diffuser wall so as for counteracting or delaying a limit surface separation of the main flow. The aperture may have an arc-shaped passage channel having a convex curvature relative to the main flow for utilizing the Coanda effect. A gas turbine may comprise the diffuser with an aperture and a central body with an aperture, each for providing a secondary flow of fluid into the diffuser. The gas turbine may comprise the diffuser and may arrange the aperture downstream relative to the diffuser inlet but upstream relative to limit surface separation. Ordinary vacuum catchers have their outlet at the pump side. It is a disadvantage of vacuum catchers that parts of the held object may get loose and get drawn in the direction of the pump. This relates particularly to vacuum catchers for foodstuffs, such as fish and meat, of which vacuum hoses, filters and pumps must be cleaned in order to avoid blocking and not least to comply with hygienic regulations.

Ordinary vacuum catchers with several suction cups having a common vacuum hose also have the disadvantage in that if one or more of the suction cups do not rest against the object to be caught, the open suction cups will draw so much air that the correctly attached suction cups do not have their desired effect, incurring that the object may not be caught sufficiently well. This is often valid for foodstuffs of filet shape with irregular and varying perimeter.

Cylindrical Coanda effect pumps may be used as vacuum catchers, but the feature that the secondary air inlet is axial with the sleeve makes such a vacuum catcher extend in the height and makes it difficultly inserted into textile storage shelves, paper shelves, skin store shelves, etc., and it is further a disadvantage that such cylindrical pumps eject the accelerated secondary air axially with the primary air and thus additionally reduces the usefulness in shelves with low shelf separation. An advantage of the cylindrical Coanda effect pump is that the primary air inlet may not be polluted by particles or liquids from the secondary fluid.

Thus there is a desire for and a need of a low vacuum catcher in which the fluid or the pump system is not subject to the risk of being polluted by particles or liquids in the fluid, and in which the vacuum catcher maintains its catching ability even though its bearing against the object to be lifted is not complete. There is also a need for a low vacuum catcher which is able to lift fragile, easily bent or deformable objects with an easily controllable and even lifting force even when the surface to be attached of the object is uneven, varying or diffuse.

Summary of the invention

The invention provides a solution to the above-mentioned problems and is an ejector for fluids comprising the following features: - a first inlet for primary fluid to a first channel for primary fluid to a distribution chamber; - one or more second inlets for secondary fluid to a second chamber for secondary fluids, in which said secondary fluid inlet is provided with an outlet to an extended outlet channel with a first and a second wall;

- a so-called top plate or first plate, closing a first end of said secondary fluid chamber and which forms a ceiling in said outlet channel;

- a second plate closing a second end of said secondary fluid chamber and which forms a bottom in said outlet channel;

- a linear slit from said distribution chamber which ends up laterally in said outlet, having an angle (alpha) with said outlet channel's direction, in which said slit extends generally in the entire height of said secondary fluid, from said second plate to said first plate;

- wherein a first wall of said linear slit to a first side ends up with an abrupt widening towards said secondary fluid chamber; and

- wherein a second wall of said linear slit along a second side has its continuation flush with a guide wall which continues as said first wall; wherein said guide wall is arranged for leading said flow of primary fluid to said outlet channel and simultaneously create a suction effect which brings secondary fluid out along said outlet channel.

Short figure captions

Fig. 1 is a plane section through an ejector according to the invention in which said inlet for secondary air and thus the suction action takes place along a z-axis normal to the plane of the drawing, the inlet for secondary air takes place from the left side of the drawing, and in which the outlet for primary air and secondary air is towards the right side of the drawing. The primary air is pumped in towards the outlet from the secondary air chamber from one side and laterally relative to the outlet channel's direction.

Fig. 2a is a plane section through a bilateral ejector according to an embodiment of the invention, in which the primary air is pumped in towards the outlet from the secondary air chamber symmetrically from both sides of the outlet channel's direction and at a straight angle on the direction of the outlet channel.

Fig. 2b is a plane section through a double-sided ejector according to a variety of an embodiment of the invention from Fig. 2a, in which the primary air in this embodiment is pumped in towards the outlet from the secondary air chamber symmetrically from both sides of the outlet channel's direction, but which forms an angle (alpha) on the direction of the outlet channel. Fig. 3 illustrates, in an exploded isometric view, a low, prismatic embodiment of an ejector according to the embodiment of the invention corresponding to Fig. 1 , in which said suction inlet runs through said prism's second plate or so-called bottom plate, axially into a cylindrical (or prismatic) secondary air chamber where the secondary air path deviates perpendicularly and runs along to an outlet channel in a short end of the prism. In this figure a so-called "monolateral" primary air path is shown.

Fig. 4 illustrates, in the same way as Fig. 3 does, a low prismatic embodiment of an ejector according to the invention, here corresponding to Fig. 2a in that the embodiment comprises a so-called double-sided primary air path.

Fig. 5 is an isometric view of an embodiment of the invention wherein several ejectors are coupled together in one single prism with a common supply channel to several secondary fluid channels arranged between two top- and bottom plates also called a first plate and a second plate, wherein each secondary fluid chamber has separate supply holes through the second plate and wherein each secondary fluid chamber has an adjacent primary fluid chamber having each their inlet from the common fluid supply channel and wherein each secondary fluid chamber's associated outlet channel runs into a common outlet channel.

Fig. 6 is an exploded isometric view of the multiple ejector embodiment of Fig. 5, showing that all the ejector chambers may be formed as an ejector core having a continuous, linearly extruded or machined cross-section along the entire height of the ejector core, and provided with a tight top plate and a perforated bottom plate or second plate, and having primary fluid inlets in one end and main outlet for all fluids in the ejector core's opposite end.

Fig. 7 roughly illustrates a longitudinal section of an ejector according to the invention in which two alternative positions of the inlet and the primary air channel are indicated.

Fig. 8 shows a perspective view and longitudinal section through a cylindrical Coanda effect pump according to the background art.

Fig. 9 illustrates an alternative embodiment of the invention in which the ejector is shaped as an extended prism having an extended secondary chamber and inlets for the secondary air along a long side of the prism and ejection of primary and secondary air along an extended slit in another long side of the prism being orthogonal to the first long side of the prism.

Fig. 10 shows a rough sketch in which an ejector according to the invention is mounted on a multi-linked mechanical arm and arranged for catching and displacing animal skins.

Description of embodiments of the invention

Fig. 1 shows a plane section through a basic unit (0) of an ejector for fluids according to the invention wherein the inlet (81) for secondary air (7), and thus the suction action, takes place along the z-axis normal to the plane of the drawing, and wherein the inlet (2) of primary air (1), which is pressurized, is from the left side of the drawing. The outlet for primary air and secondary air is towards the right side of the drawing through the outlet channel (6). The primary air (1) is pumped in towards the outlet (86) from the secondary fluid chamber (8) monolaterally and sidewards relative to the direction of the outlet channel (6). The main features of the embodiment shown in Fig. 1 are built up as follows: A first inlet (2) for primary air (1) leads to a first channel (3) for the primary fluid (1) to a distribution chamber (4) for said primary fluid (1). The primary fluid may be any fluid, e.g. air or water. One or more second inlets (81) for secondary fluid (7), here shown running through a so-called bottom plate or second plate (13), leads to a second chamber (8) for secondary fluid (7), wherein said secondary fluid chamber (8) is provided with an outlet (86) to an extended outlet channel (6), here shown towards the right in the drawing, with a first and a second wall (61 , 61') in the outlet channel. The secondary fluid chamber (8) may be cylindrically or prism-shaped. A so-called top plate or second plate (14) closes a first end of said secondary fluid chamber (8) and may at the same time form a ceiling in the outlet channel (6). A second plate (13) in the secondary fluid chambers opposite end relative to the first plate (14) closes a second end of the secondary fluid chamber (8) and may at the same time form a bottom in the outlet channel (6). So far, the mechanical basis is given for the further features which provide the possibility of utilizing the Coanda effect. A linear slit (5) from said distribution chamber (4) runs laterally into said outlet (86). The slit may in one embodiment run out at straight angles, i.e. orthogonally, to the direction of the outlet channel (6) such al illustrated in Fig. 1 and in fig. 2a, or under an angle (alpha) with the direction of the outlet channel such as illustrated in Fig. 2b. The slit (5) extends generally along the entire height of the secondary fluid chamber (6), from the second plate (13) to the first plate (14). A first wall (51) of the linear slit's (5) first side, here shown in the direction towards the left in Fig. 1 , runs out with an abrupt widening towards the secondary fluid chamber (8). A second wall (52) of the linear slit's (5) other side has an extension flush with a guide wall (62) which runs into its continuation in said first wall (61). The guide wall (62), which may also be called the Coanda wall (62), is arranged for conducting the flow of primary fluid (1). The guide wall (62) is in a preferred embodiment smooth arc-shaped such as shown in Figs. 2a and 2b, but may also work if combined by straight section having a small kink angle between each section. The primary fluid (1) is thus led to the outlet channel (6) so as for the primary fluid flow to entrain secondary fluid (7) out of the outlet channel. Thus we may call the linear slit (5) laterally surrounded on the first side by said first wall (51) which deviates abruptly to a first direction, and to the other side of the continuous Coanda wall (62), a linear Coanda nozzle (5).

In an embodiment shown in Fig. 1 and in Fig. 2a the slit (5) for the primary air (1) is directed mainly at right angles relative to the direction of the outlet channel (6). In another embodiment shown in Fig. 2b the slit (5) forms an angle (alpha) with the direction of the outlet channel (6). In the embodiment shown in Fig. 2b the slit's air flow runs out under an angle alpha less than 90 degrees component in the direction of the outlet channel. One may also imagine that the invention would work if the angle (alpha) is somewhat more than 90 degrees.

The illustrated embodiment of Fig. 1 does not limit the position of the inlet (2) and the path of the channel (3) of the primary fluid (1). In Fig. 1 the inlet is placed on the left short side of the cross section of a rectangular block. However the inlet may be placed laterally, i.e. in a long side of the prism, or at the same short side as the mouth of the outlet channel (6), such as indicated by the two alternative positions of the inlet and the channel indicated as two different alternatives having the reference numerals "[2]" and "[3]" in fig. 7. It is also possible to have a parallel or coaxial arrangement of the inlet channel (3) and the outlet channel (6).

In a preferred embodiment of the invention the primary fluid (1) and the secondary fluid (7) are gaseous, preferably air. In most applications as a vacuum catcher it is natural that particularly the secondary fluid (7) is air. However the invention will work well if the primary fluid (1) and the secondary fluid (7) are e.g. water and the vacuum catcher shall be used under water.

In the embodiment of the invention illustrated in Fig. 3 the secondary fluid inlets (81) run through the second plate (13) which is also called the bottom plate. In this way a suction opening for the secondary fluid is formed in a surface that is directed at right angles with the outlet channel (6). This is a significant advantage relative to a cylindrical ejector of the background art, wherein the inlet and the outlet are axially oppositely directed, and the present invention makes, in this embodiment, that one may form a rather flat and low vacuum catcher which may be built having a few millimetres or centimetres height and which may thus be inserted into storage shelves for textiles, papers, skins, etc. for catching sheets even where there is a low clearance between the upper sheet and an overlying shelf plate.

In an embodiment of the invention the secondary fluid chamber is cylindrical, i.e. that the ejector's secondary fluid chamber (8) has a generally cylindrical wall (88) which extends from the second plate (13) to the top plate (14). This is most clearly illustrated in Figs. 3 and 4. The cylindrical wall (88) has a central axis (82) which may be erected at right angles to the second plate (13) and the top plate (14). This chamber may alternatively be prism-shaped with it central axis (82) in the same direction as for the cylinder shaped embodiment. Notice that a cylindrical wall of the secondary fluid chamber according to the invention has its axis across the outlet channel (6), and not parallel to the outlet channel in the case of a cylindrical vacuum ejector according to the Coanda principle according to background art as illustrated in Fig. 8.

In the embodiment shown in Figs. 2 and 3, and generally also in Figs. 2a, 4, 5, and 6, the primary fluid inlet (2) is axial with the outlet channel (6) and arranged at the opposite side of the secondary fluid chamber (8) relative to the primary fluid inlet (2). Further, in each and every of Figs. 1 - 4, an arc-shaped path of the primary fluid channel is shown, in which the primary fluid channel (3) which runs from the primary fluid inlet (2) to the distribution chamber (4), extends around a part of the cylindrical wall (88) of the secondary fluid chamber (8). This is partly for achieving that the inlet (2) for primary air shall be arranged axially with the outlet channel (6) as explained above, but also for forming a mirror symmetric ejector as explained below. In having inlets for primary fluid (1) and the outlet channel (6) arranged in the short sides of the prism, and not in its flat sides, one avoids increasing the height of the prism and maintains the low height of the vacuum catcher. Thus in a plane ejector the separation between the second plate (13) and the first plate (14) generally less than the diameter of the secondary fluid chamber (8), such that the ejector is generally plate shaped. The plane ejector may, as described above, be used as a plane catcher in which the second surfaces (13) one or more inlets (81) for secondary fluid (7) is arranged for being brought against the surface of an object in order to form an underpressure in the secondary fluid (7) in the area between the object's surface and the second plate (13). In an embodiment of the invention the ejector may have a cylindrical distribution chamber, i.e. in which the distribution chamber (4) has a generally cylindrical wall (44) and has an axis (42) which extends orthogonally from the second plate (13) to the top plate (14). This is illustrated in fig. 3. This primary air chamber may alternatively have a prism shape having the same main axial direction (42) as the cylindrical chamber.

In Fig. 5 and 6 it is shown an embodiment of a multiple-chamber ejector according to the invention, comprising two or more basis units' (0) arranged in a block or a prism (10) between two parallel top- and bottom plates (14, 13), where each base units (0) secondary fluid chamber (8) has an adjacent primary fluid chamber (4) having each their inlet channel (3) for the primary fluid (1) to the chamber (4) from a common fluid supply channel or a primary fluid manifold (33) arranged between the top- and bottom plates (14, 13), and wherein the corresponding outlet channel (6) for each secondary fluid chambers runs into a common outlet channel or outlet manifold (66). One of the main advantages of such a multiple chamber ejector used as a vacuum gripping device is that if one or more of the inlets (81) for secondary fluid is not arranged sufficiently close to the surface of an object to be caught, the gripping power of the inlets (81) that in fact achieves the desired contact with the object to be caught, is not reduced. This is because the pressure of the primary fluid (1) is not significantly affected by to what extent air is flowing into the secondary fluid chamber (8), as opposed to vacuum suction cups with a common vacuum suction channel according to background art.

In an alternative embodiment of an ejector according to the invention, where the ejector is not plate-shaped as shown in the examples above, the distance between the second plate (13) and the first plate (14) be quite long, and at least longer than the secondary fluid chambers (8) diameter. In this way one may form an ejector stretching out longer in the z- direction than in the x- and y- direction, where the fluid inlet (81) is arranged as one or more openings along the length of the ejector through the x-z wall (92), please see Fig. 9, where the ejector according to this embodiment of the invention is blowing out air through a long slit (63) formed by the outlet channel (6) i the full length of the ejector. This may be a way of achieving larger volume capacity for the secondary fluid (1), while at the same time obtaining an extended distribution from the outlet channel (6).

According to an additional advantageous embodiment of the invention illustrated in Fig. 2a and 4, the ejector may be double-sided where a second distribution chamber (4^?) with an opposite and reciprocal linear second slit (5¹) is arranged mainly symmetrically about the secondary fluid chamber (8) and the outlet channel (6). For the case illustrated in Fig. 2a and 4 the primary fluid inlet (2) common and connected to both the first channel (3) running to the first distribution chamber (4), and also connected to a second, opposite channel (3¹) for the primary fluid ((1) to the second distribution chamber (4¹). The second slit (5¹) runs from the distribution chamber (4') and ends laterally into the outlet (86), in a right angle to the direction of the outlet channel (6). As mentioned above for the first Coanda nozzle (5), the second Coanda nozzle (5') may also extend mainly in the entire height of the secondary fluid chamber (6) from the second plate (13) to the first plate (14), and as for the first Coanda nozzle (5), a first wall (51') in the linear second Coanda nozzle (5') to a first side falls into an abrupt widening towards the secondary fluid chamber (8); and a second wall (52') in the linear second Coanda nozzle (5') has, along a second opposite side its continuation flush with a second guide wall (62') which continues to make up the second wall (6T) of the outlet channel (6). In this way one may achieve approximately a doubling of the pump capacity for the ejector according to the embodiment of the invention shown in Fig. 2a or 2b relative the monolateral Coanda nozzle embodiment explained above and shown in Fig. 1.

The ejector according to the invention may have a mainly invariable cross-section perpendicular to the axial direction through the secondary chamber (8), the distribution chamber (4), the Coanda nozzle (5) and the outlet channel (6) being mainly similar in all heights between the second plate (13) and the top plate (14). Such an ejector may be simple to make by machining of a prism shaped material (9) or extrusion of metal or plastic.

To work as a vacuum gripping device, the ejector according to the invention may be held by a controllable arm (11) arranged for laying the ejector's secondary fluid inlet (81) against an object to be caught and / or moved, see Fig. 10. The vacuum gripping device according to the invention will be particularly suited to grip and hold fragile objects like paper, cloths, skin, fillets of fish and meat, porous objects like foamed plastic or other more or less solid foams with low density, and other objects with low weight and bend strength. A vacuum gripping device according to the invention may be used to grip and lift carbon fibres or carbon fiber cloths for e.g. composit production of airplane components, fibreglass mats for the production of e.g. wind turbine wings, relocation of fibreglass cords, relocation of plate-shaped components in vehicle manufacturing, and gentle gripping and relocation of silicon [solar] cells or silicon [solar] cell arrays during production of solar cells.

Claims

1. An ejector for fluids, comprising at least one basic unit comprising the following features:

- at least one primary fluid inlet (2) for primary fluid (1) via a primary fluid channel (3) to a distribution chamber (4);

- one or more secondary fluid inlets (81) for a secondary fluid (7) to a secondary fluid chamber (8), said secondary fluid chamber (8) having an outlet (86) to an extended outlet channel (6) having a first and an opposite second wall (61, 61');

- a first plate (14) which covers a first end of said secondary fluid chamber (8) and which forms a third wall in said outlet channel (6);

- a second plate (13) which covers a second, opposite end of said secondary fluid chamber (8) and which forms a fourth wall i said outlet channel (6);

- a linear Coanda-nozzle (5) from said distribution chamber (4) which leads into a lateral portion of said outlet (86), having an angle relative to the direction of said outlet channel (6), and which extends generally in the entire height of said secondary fluid chamber's (6) height between said second plate (13) and said first plate (14); in which said Coanda-nozzle (5) is arranged for diverting primary fluid (1) to said outlet channel (6) and thus creating a suction effect at said secondary fluid inlet (81).

2. The ejector according to claim 1, in which said secondary fluid inlets (81) run through said second plate (13).

3. The ejector according to claim 1, in which

- a first wall (51) of said linear Coanda nozzle (5) to one side falls into an abrupt widening towards said secondary fluid chamber (8), and

- a second wall (52) of said linear Coanda nozzle (5) along another side has its continuation flush with a guide wall (62) which continues flush with said first wall (61) of said outlet channel (6).

4. The ejector according to claim 1, in which said secondary fluid chamber (8) has a generally cylindrical wall (88) extending from said second plate (13) to said first plate (14), said cylindrical wall (88) has a central axis (82) orthogonal to said second plate (13) and said first plate (14).

5. The ejector according to claim 1, in which said primary fluid inlet (2) is axial with said outlet channel (6) and arranged at an opposite end of said secondary fluid chamber (8) relative to said primary fluid inlet (2).

6. The ejector according to claims 4 and 5, in which the primary fluid channel (3) between said primary fluid (2) and said distribution chamber (4) extends around a part of said secondary fluid chamber's (8) cylindrical wall (88).

7. The ejector according to claim 1, in which said distribution chamber (4) has a generally cylindrical wall (44) and has an axis (42) which extends orthogonally between said second plate (13) and said first plate (14).

8. The ejector according to claims 2 and 4, in which the separation between said second plate (13) and said first plate (14) is generally less than the diameter of said secondary fluid chamber (8), so as for said ejector being generally plate-shaped.

9. The ejector according to claim 8, in which said second plate's (13) one or more second inlets (81) for secondary fluids (7) is arranged for bearing against an object's surface for forming an underpressure in said secondary fluid (7) in the range between said object's surface and said second plate (13).

10. The ejector according to claim 2, with a common fluid supply channel or inlet manifold (33) which supplies primary fluid to two or more basis units' (0) primary fluid channels (3).

11. The ejector according to claim 2, in which said two or more basis units' (0) outlet channels (6) lead into a common outlet channel or outlet manifold (66).

12. The ejector according to claims 2 and 4, in which said separation between said second plate (13) and said first plate (14) is longer than the diameter of said secondary fluid chamber (8).

13. The ejector according to claim 1,

- in which said primary fluid inlet (2) further is connected with a second, oppositely arranged channel (3¹) for said primary fluid inlet (1) to a second distribution chamber (4¹) with an opposite and corresponding linear second Coanda nozzle (5') arranged generally symmetrically about said secondary fluid chamber (8) and said outlet channel (6).

14. The ejector according to claim 13,

- in which said second Coanda-nozzle (5') the nozzle aperture (5') running from said distribution chamber (4¹) and which leads laterally into said outlet (86) under an angle with the direction of the outlet channel (6), in which said second, linear Coanda nozzle (5^T) extends generally in the entire height of said secondary fluid chamber {©)(8) between said second plate to said first plate (14);

- in which a first wall (51') in said second linear Coanda nozzle (5¹) leads, to a first side, in an abrupt widening towards said secondary fluid chamber (8); and

- in which a second wall (52') in said linear Coanda nozzle (5¹) along a second, opposite side has its continuation flush with a second guide wall (62') which in its continuation constitutes said second wall (6T) of said outlet channel (6).

15. The ejector according to claim 1, in which a plane section orthogonal to said axial direction through said secondary chamber (8), said distribution chamber (4), said Coanda nozzle (5) and said outlet channel (6) is the same generally in all heights between said second plate (13) and said first plate (14).

16. The ejector according to claim 1, in which said primary fluid (1) and said secondary fluid (7) are gaseous, e.g. air.

17. The ejector according to claim 1 , in which said primary fluid (1) and said secondary fluid (7) are liquid, e.g. water.

18. The ejector according to claim 1 comprising a controllable arm (11) arranged for holding and laying said ejector's secondary fluid inlet (81) against an object so as for exerting a suction force on said object in order to hold or displace said object.

19. Use of the ejector according to claim 1 , by laying said secondary fluid inlet (81) against a piece of foodstuff so as for catching or lifting said piece of foodstuff by means of the underpressure formed between said secondary fluid inlet (81) and said piece of foodstuff by so doing.

20. Use of the ejector according to claim 1 , by laying said secondary fluid inlet (81) against a sheet or foil of paper, plastic or other material, so as for catching or lifting said sheet by means of the underpressure formed between said secondary fluid inlet (81) and said sheet by so doing.

21. Use of the ejector according to claim 1 , by laying said secondary fluid inlet (81) against a portion of a textile so as for catching or lifting said portion of textile by means of the underpressure formed between said secondary fluid inlet (81) and said portion of textile by so doing.

22. Use of the ejector according to claim 1 , by laying said secondary fluid inlet (81) against a piece of animal skin so as for catching or lifting said piece of animal skin by means of the underpressure formed between said secondary fluid inlet (81) and said piece of animal skin by so doing.

23. Use of the ejector according to claim 1, by laying said secondary fluid inlet (81) against a piece of more or less solid foam material so as for catching or lifting said foam material by means of the underpressure formed between said secondary fluid inlet (81) and said foam material by so doing.