Multistage ejector

Abstract

A multistage ejector has a nozzle arrangement, which has at least three nozzles which are arranged in series in the direction of a longitudinal axis, wherein the nozzles are designed for passage of a throughflow of a fluid, wherein a fluid gap is provided between adjacent nozzles in each case, wherein at least two of the at least three nozzles are interconnected monolithically to form a nozzle string, and wherein the nozzle string is arranged at least partially in a sleeve and the nozzle string and the sleeve are detachably fastened to each other. The nozzle string and the sleeve are axially fastened to each other by fastening mechanism which acts in a positively locking manner.

Claims

1. A multistage ejector, comprising: a nozzle arrangement having at least three nozzles arranged in series in a direction of a longitudinal axis, the nozzles adapted to provide passage of a throughflow of a fluid, a fluid gap being provided between adjacent nozzles, at least two of the at least three nozzles are interconnected monolithically to form a nozzle string, a sleeve including an inside and an outside, the sleeve having a first radial opening and a second radial opening opposing the first radial opening, wherein the first and second radial openings are each configured to pass from the inside of the sleeve to the outside of the sleeve, the nozzle string being arranged at least partially in the sleeve; a check valve for closing and freeing the first and second radial openings, the check valve including a slotted annular band having a first portion and a second portion extending circumferentially around the nozzle string, wherein the first and second portions are aligned with the first and second radial openings, respectively, and wherein the slotted annular band is connected monolithically via an axial tab to a discontinuous locking ring, the discontinuous locking ring including a slotted region configured to engage with a radial tongue in the nozzle string defining a rotational position of the check valve relative to the nozzle string, wherein the discontinuous locking ring is disposed between two spaced apart flanges for axially securing the check valve from displacement; and a fastening mechanism rotationally detachable and axially fastening the sleeve and the nozzle string to each other, the fastening mechanism being a positively locking fastening mechanism.

2. The ejector of claim 1, wherein the fastening mechanism fastens the nozzle string and the sleeve to each other in a rotationally secured manner relative to each other.

3. The ejector of claim 1, wherein the at least three nozzles comprise a driver nozzle and at least two receiver nozzles, wherein the at least two receiver nozzles form the monolithic nozzle string.

4. The ejector of claim 1, wherein the nozzle arrangement has at least four nozzles comprising a driver nozzle and at least three receiver nozzles, wherein the at least three receiver nozzles form the monolithic nozzle string.

5. The ejector of claim 1, wherein the fastening mechanism is a latching connection.

6. The ejector of claim 1, wherein the fastening mechanism is a combination of a plug-in and twist connection and a latching connection.

7. The ejector of claim 1, wherein the fastening mechanism is arranged on the nozzle string at a distance from an end of said nozzle string so that the nozzle string projects beyond the sleeve.

8. The ejector of claim 1, wherein the fastening mechanism has at least one radially projecting tongue on the nozzle string and at least one recess on the sleeve, the at least one recess extends parallel to the longitudinal axis, and the at least one recess adjoins a further recess on the sleeve which extends in a circumferential direction around the longitudinal axis.

9. The ejector of claim 1, wherein the nozzle string has a flange abutting against an end face of the sleeve when the nozzle string is being connected to the sleeve.

10. The ejector of claim 1, wherein the nozzle string includes the radial tongue integrally formed in and projecting radially outward from a center of the nozzle string and between free ends of the discontinuous locking ring, and wherein the radial tongue prevents rotation of the check valve around the longitudinal axis.

11. The ejector of claim 10, wherein the two spaced apart flanges are integrally formed on an outer side of the nozzle string forming a seat contacting at least one surface of the discontinuous locking ring.

12. The ejector of claim 1, wherein the fastening mechanism is a plug-in and twist connection.

13. The ejector of claim 12, wherein the fastening mechanism is a bayonet connection.

14. The ejector of claim 1, wherein two or more axial bridges are formed between each of the at least two of the at least three nozzles providing the monolithic interconnection.

15. The ejector of claim 14, wherein the two or more axial bridges are formed in the direction of the longitudinal axis of the nozzle arrangement.

16. The ejector of claim 15, wherein the two or more axial bridges are formed on peripheral surfaces of the at least two of the at least three nozzles.

17. The ejector of claim 16, wherein two axial bridges of the two or more axial bridges are disposed opposite one another radially about the fluid gap.

18. The ejector of claim 17, wherein the multistage ejector includes an inlet side disposed on a first end of the nozzle arrangement and an outlet side disposed on a second and opposite end of the nozzle arrangement, and wherein a portion of the two or more axial bridges connecting a first nozzle to a second nozzle in the nozzle string tapers outwardly from a peripheral surface of the first nozzle in a direction of the outlet side.

19. The ejector of claim 17, wherein a third axial bridge is disposed between the two axial bridges on one side.

20. The ejector of claim 19, wherein the check valve is axially offset from the fluid gap provided between adjacent nozzles in the nozzle string such that the check valve is not radially overlapping any portion of the fluid gap.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment is shown in the drawings and is described in more detail in the following with reference to the drawings. In the drawings:

(2) FIG. 1a is a side elevation view of a multistage ejector according to an embodiment of the present invention;

(3) FIG. 1b is a cross-sectional elevation view of the embodiment of FIG. 1a and taken along line IB-IB of FIG. 1a;

(4) FIG. 2a is a side elevation view of the multistage ejector according to the embodiment of FIG. 1a and rotated 90 degrees about its longitudinal axis with respect to FIG. 1a;

(5) FIG. 2b is a cross-sectional elevation view of the embodiment of FIG. 2a and taken along line IIB-IIB of FIG. 2a;

(6) FIG. 3 is a perspective view of a multistage ejector according to the embodiment of FIG. 1a and wherein a nozzle string and a sleeve are partially separated from each other;

(7) FIG. 4 is a side elevation view of a multistage ejector according one embodiment of the present invention;

(8) FIG. 5 is a side elevation of the multistage ejector of the embodiment of FIG. 4 wherein the ejector is rotated 180 degrees about the longitudinal axis with respect to FIG. 4;

(9) FIG. 6 is a side elevation view of a multistage ejector according one embodiment of the present invention;

(10) FIG. 7 is a perspective view of a check valve according to one embodiment of the present invention; and

(11) FIG. 8 is an elevation view of the ejector of the embodiment of FIG. 1a taken at line VII-VII of FIG. 1a.

DESCRIPTION OF A PREFERRED EXAMPLARY EMBODIMENT

(12) Shown in FIGS. 1a) and b) and also in FIGS. 2a) and b) is a multistage ejector which is provided with the general reference numeral 10. Further details of the ejector 10 are apparent from FIGS. 3 to 8.

(13) The ejector 10 is used for creating a negative pressure or vacuum.

(14) The ejector 10 has a nozzle arrangement 12 with altogether four nozzles 14, 16, 18 and 20 in the depicted exemplary embodiment. The nozzles 14, 16, 18 and 20 are arranged in series in the direction of a longitudinal axis 21.

(15) The nozzles 14, 16, 18 and 20 are designed for passage of a throughflow of a fluid, especially compressed air. In FIGS. 1b) and 2b), the fluid flow is indicated by an arrow 22 on the inlet side and by arrows 24 on the outlet side.

(16) The nozzle 14 forms the driver nozzle, and the nozzles 16, 18 and 20 form the receiver nozzles, as seen in the flow direction of the fluid. The nozzle 14 according to FIG. 1a) has a fluid passage 26, the nozzle 16 has a fluid passage 28, the nozzle 18 has a fluid passage 30 and the nozzle 20 has a fluid passage 32. In this case, a cross section of the fluid passage 28 is larger than a cross section of the fluid passage 26, and the fluid passage 30 has a larger cross section than the fluid passage 28, and the fluid passage 32 has a larger cross section than the fluid passage 30.

(17) The nozzles 16, 18, 20 are interconnected monolithically to form a one-piece nozzle string 34. The nozzle 14 is designed as an individual nozzle.

(18) Shown in FIG. 6 is the nozzle arrangement 12 with the nozzle string 34 and the nozzle 14 alone.

(19) The nozzle string 34 is produced as a whole in one piece from plastic. The nozzle 14 is produced from aluminium, for example.

(20) The nozzles 14, 16, 18 and 20 according to FIG. 1a) and FIG. 6 in each case leave a fluid gap free between each other, specifically a fluid gap 36 between the nozzle 14 and the nozzle 16, a fluid gap 38 between the nozzle 16 and the nozzle 18 and also a fluid gap 40 between the nozzle 18 and the nozzle 20.

(21) In order to realize on the one hand the monolithic connection of the nozzles 16, 18 and 20, and on the other hand the fluid gaps 38 and 40 on the nozzle string 34, the nozzle 16 is connected monolithically to the nozzle 18 via a multiplicity ofin this case threenarrow, axial bridges 42, and the nozzle 18 is connected monolithically to the nozzle 20 via narrow, axial bridges 44. The bridges 42 or 44 are distributed around the longitudinal axis 21 and ensure a sufficiently large opening cross section of the fluid gaps 38 and 40.

(22) The nozzle 14 and also the nozzle string 34 with the nozzles 16, 18 and 20 are accommodated at least partially in a totally monolithic, i.e. one-piece sleeve. The sleeve 46 has a first end 48 in the region of the nozzle 14 and a second end 50 in the region of the nozzle 20. The nozzle 20 projects beyond the second end 50 of the sleeve 46 in this case.

(23) The nozzle string 34 and the sleeve 46, according to FIGS. 1a) and b) and also FIGS. 2a) and b), are fastened to each other axially, that is to say in the direction of the longitudinal axis 21, and around the longitudinal axis 21 in the rotational direction, by means of a fastening mechanism 52 which acts in a positively locking manner. The fastening mechanism is also described below with reference to FIG. 8.

(24) The fastening mechanism 52 is arranged on the sleeve 46 on the end side, specifically in the region of the second end 50, whereas the fastening mechanism 52 is arranged on the nozzle string 34 at a distance from one end 54 of said nozzle string 34.

(25) The fastening mechanism 52 is designed as a plug-in and twist connection, especially as a bayonet connection. To this end, the fastening mechanism 52 has two radially projecting tongues 56 and 58 (see FIG. 1b) on the nozzle string 34, which extend partially circumferentially around the longitudinal axis 21. The tongues 56 and 58 are offset in relation to each other by 180 around the longitudinal axis 21. The tongues 56 and 58 have radial surfaces 57 and 59 which are curved, but with an eccentricity with regard to the longitudinal axis 21. In this way, the surfaces 57 and 59 act as lead-in bevels when closing the fastening mechanism 52 if the nozzle string 34 is rotated relative to the sleeve 46.

(26) The fastening mechanism 52 furthermore has two recesses 60 and 62, extending in the direction of the longitudinal axis 21, which are formed as grooves on the inner side of the sleeve 46. The recesses 60 and 62 have an extent in the circumferential direction around the longitudinal axis 21 which is slightly larger than the circumferential extent of the tongues 56 and 58 on the nozzle string 34. The axial extent of the recesses 60 and 62 is indicated in FIG. 1a) with broken lines for the recess 60. The recesses 60 and 62 are open towards the outermost end of the end 50 of the sleeve 46.

(27) A further recess 64 adjoins the axial recess 60 in the circumferential direction around the longitudinal axis 21, and a further recess 66 adjoins the axial recess 62 in the same rotational direction. The recesses 64 and 66 are formed as radial openings in the sleeve 46 which are set back in relation to the second end 50. In the fastened-together state of the nozzle string 34 and the sleeve 46, the radial tongues 56 and 58 engage in the recesses 64 and 66. The radial tongues 56 and 58 have a slightly greater radial extent than where it corresponds to the inside diameter of the sleeve 46 in the region of the second end 50 so that the radial tongues 56 and 58 can latch into the recesses 64 and 66. The fastening mechanism 52 is therefore not only designed as a plug-in and twist connection in the form of a bayonet connection, but additionally also as a latch-in connection.

(28) The nozzle string 34, by means of the fastening mechanism 52, can therefore be fastened axially on the sleeve 46 and in the rotational direction around the longitudinal axis 21.

(29) The nozzle string 34 has a flange 68 at a distance from its end 54, which in this case is formed as a fully circumferentially extending, radially projecting annular flange which comes to lie against an end face 70 of the sleeve 46 when the nozzle string 34 and the sleeve 46 are being fastened to each other. The flange 68 therefore limits the insertion depth of the nozzle string 34 into the sleeve 46.

(30) FIGS. 1a) and b) and also FIGS. 2a) and b) and FIG. 8 show the ejector 10 in a state in which the nozzle string 34 and the sleeve 46 are fastened to each other by means of the fastening mechanism 52. For releasing the nozzle string 34 from the sleeve 46, starting from the position in FIG. 8, the nozzle string 34 is first of all rotated anticlockwise around the longitudinal axis 21 relative to the sleeve 46, as a result of which the radial tongues 56 and 58 disengage from the recesses 64 and 66. In the process, the radial tongues 56 and 58 enter the axial recesses 60 and 62. The rotational travel of the nozzle string 34 relative to the sleeve 46 which is required for this is approximately 40, but at least less than 45. After the previously described rotation of the nozzle string 34 relative to the sleeve 46, the nozzle string 34 can be fully withdrawn from the sleeve 46, as is indicated in FIG. 3 by an arrow 72. The assembling of the injector 10, that is to say the connecting of the nozzle string 34 to the sleeve 46, is carried out in reverse sequence, that is to say the nozzle string 34 is first of all inserted into the sleeve 46, specifically in a relative rotational position to the sleeve 46, in which the radial tongues 56 and 58 can enter the axial recesses 60 and 62. When the flange 68 abuts against the end face 70, the nozzle string 34 is rotated clockwise (FIG. 8) relative to the sleeve 46 until the radial tongues 56 and 58 engage with the recesses 64 and 66. The bevelled surfaces 57 and 59 of the tongues 56 and 58 reduce the expenditure of force during the rotation and ensure a distinctly perceptible latching of the tongues 56 and 58 into the recesses 64 and 66 by the leading end of the tongues 56 and 58, during the rotation of the nozzle string 34 for the closing of the fastening mechanism 52, having a smaller radial extent than the trailing end.

(31) The sleeve 46 furthermore has a plurality ofin this case sixradial openings 74a, 74b, 76a, 76b, 78a and 78b which enable communication of the inside of the sleeve 46 with its outside. For the freeing and closing of the openings 74a, b; 76a, b and 78a, b, provision is made for check valves 80, 82 and 84, of which the check valves 82 and 84 are connected to the nozzle string 34, whereas the check valve 80 is connected to the nozzle 14. The check valves 82 and 84 are detachably connected to the nozzle string 34 and the check valve 80 is detachably connected to the nozzle 14. The check valves 80, 82 and 84 can therefore be removed from the nozzle 14 or from the nozzle string 34 for the purpose of exchange in the event of wear.

(32) The embodiment of the check valves is described below inter alia with reference to FIGS. 4 and 5 and also FIG. 7. FIG. 7 shows the check valve 84 on its own by way of example. The same description also applies to the two other check valves 80 and 82.

(33) The check valve 84, which overall is produced from an elastomer or rubber, has a slotted annular band 86 which on account of its circumferential discontinuity forms two wings 88 and 90. In the state attached on the nozzle string 34, the wing 88 serves for closing the opening 78b and the wing 90 serves for closing the opening 78a of the sleeve 46.

(34) The annular band 86 is connected monolithically via an axial tab 92 to a partially circumferentially extending or discontinuous ring 94.

(35) As is described below with reference to the check valve 84, the check valves 80, 82 and 84 on the nozzle 14 or on the nozzle string 34 are secured against rotation around the longitudinal axis 21 and against displacement in the direction of the longitudinal axis 21 relative to the nozzle 14 or to the nozzle string 34.

(36) To this end, for the check valve 84 according to FIG. 4 a seat 95 is formed on the nozzle string 34 and is formed by two radial flanges 96 and 98 which are designed as fully circumferentially extending annular flanges and the spacing of which corresponds to the thickness of the ring 94. The ring 94 is inserted between the two flanges 96 and 98 when the check valve 84 is being attached to the nozzle string 34. The check valve 84 is therefore axially secured against displacement between the flanges 96 and 98. The seat 95 also has a radial tongue 100 between the two flanges 96 and 98 which defines the rotational position of the check valve 84 relative to the nozzle string 34 with regard to the longitudinal axis 21 and, via the fastening mechanism 52, relative to the openings 78a and 78b and also secures the check valve 84 against rotation around the longitudinal axis 21 relative to the nozzle string 34. For this, the check valve 84 is attached to the nozzle string 34 so that a slotted region 102 of the ring 94 comes to lie level with the tongue 100 so that the two ends 104 and 106 of the ring 94 are supported on both sides of the tongue 100.

(37) When the ejector 10 is being assembled, the check valves 82 and 84 are first of all attached to the nozzle string 34 in the predetermined axial position and rotational position. The nozzle string 34 is then inserted into the sleeve 46, wherein as a result of the axial securing of the check valves 82 and 84 on the nozzle string 34 these cannot be axially displaced relative to the nozzle string 34 when the nozzle string 34 is being inserted into the sleeve 46. With subsequent rotation of the nozzle string 34 relative to the sleeve 46 for the closing of the fastening mechanism 52, the rotational securing of the check valves 82 and 84 on the nozzle string 34 prevents an undesirable rotation of the check valves 82 and 84 relative to the nozzle string 34.

(38) The nozzles 14, 16, 18 and 20 also have slots or seats 108, 110, 112 and 114 for the location of an O-ring in each case (omitted in the drawing) in order to seal the nozzles 14, 16, 18 and 20 in sections against the sleeve 46.

(39) When in use, the ejector 10 is inserted into an ejector housingnot shownwhich has a bore which is correspondingly matched to the outside diameter of the sleeve 46. If the ejector 10 has to be withdrawn from the ejector housing for maintenance purposes, the previously described fastening mechanism 52, via which the nozzle string 34 and the sleeve 46 are fastened to each other, prevents the nozzle string 34 from being prematurely released from the sleeve 46 when an axial tensile force is being exerted upon the nozzle string 34 and prevents just the nozzle string 34 from being withdrawn from the ejector housing while the sleeve 46 remains fitted in the ejector housing. On the other hand, the fastening mechanism 52 enables a simple dismantling of the ejector 10 into the nozzle string 34 and the sleeve 46 and also enables easy assembly of these parts. When the nozzle string 34 is being inserted into the sleeve 46, the position and orientation of the check valves 82 and 84 relative to the nozzle string 34 does not alter either, as was described previously.