Fluid suction nozzle and fluid-treating apparatus

Abstract: A fluid suction nozzle and a fluid-treating apparatus for improving the cleanliness inside a local space surrounded by an air curtain. The suction nozzle (20) has a suction passage (24) and plural annular discharge passages (25, 26) surrounding the suction passage. The nozzle is connected with an air cleaner (31), etc. The air inside the local space is drawn in through the suction passage (24). At the same time, a larger amount of air is discharged from the discharge passages (25, 26). The flow velocity of fluid inside the outer discharge passage (26) is set smaller than that inside the inner discharge passage (25).

Description: FIELD OF THE INVENTION The present invention relates to a fluid-treating apparatus adapted to clean, condition, or otherwise treat the air inside a local space surrounded by an air curtain. BACKGROUND OF THE INVENTION The present applicant has already filed Japanese Patent application Ser. No. 169893/1990 for "Fluid Suction Nozzle and Fluid-Treating Apparatus". These nozzle and apparatus are shown in Fig. 8, where the suction nozzle, indicated by numeral 1, is connected with an air cleaner 3 via a duct 2. The nozzle 1 comprises an inner member 4 and an outer member 5 that is slightly spaced from the inner member 4. When a fan 6 incorporated in the air cleaner 3 is driven, the air discharged from the fan passes through an outer passage 7 formed inside the duct 2. The air then passes through an annular discharge passage 8 formed between the inner member 4 and the outer member 5 of the nozzle 1, and is forced obliquely downwardly into a room 9. A local space 10 is surrounded by this air flow, indicated by AC. The air inside the space 10 is drawn into a suction passage 11 formed inside the inner member 4 of the nozzle 1. Then, the air passes through an inner fluid passage 12 formed in the duct 2 and enters the air cleaner 3, where the air flows downwardly through a filter 13, a dust collecting material 14, and a deodorant 15. In this process, the air is cleaned. The air is again drawn into the fan 6. Subsequently, the process described thus far is repeated. In the above-described apparatus, the ratio ψ of the flow rate of air Q S drawn into the suction passage 11 to the flow rate of air Q D discharged from the discharge passage 8 is set greater than 1, i.e., ψ = Q S /Q D is greater than 1. Therefore, contaminated air around the air flow AC is caught in the air flow AC and enters the local space 10. This has set a limit to the cleaning inside the local space 10. WO-A 91/05210 discloses an apparatus for creating an air curtain extending vertically from the top to the bottom of the apparatus. The air is discharged from ports arranged coaxially so as to form a circular unidirectional laminar flow of two adjacing air streams, wherein the velocity of the outer stream is smaller than the velocity of the inner stream. A suction port is provided at the bottom of the curtain so that no recirculation areas are formed in this apparatus. EP-0 413 406 A2 discloses another apparatus for forming an air curtain by directing a jet stream onto a guide member to define a working space within the air curtain. According to this prior art it is not intended to exchange and clean the air within the working space by means of this apparatus but rather only to separate the enclosed working space from the surrounding atmosphere. The air for forming the curtain is preferably drawn from outside the working space and the air inside the curtain is thus cleaned by means of a separate fluid regulating device. FR-A-2163927 describes an apparatus in which two fluid passages are separated by a partition member and provided each with a fan to create a fluid flow therethrough. The suction port of the first fluid passage is arranged so as to be surrounded by the discharge port of the second passage forming a curtain around the suction port, while the suction port of the second passage and the discharge port of the first passage are directed to different directions away from the suction port of the first passage and the air curtain formed by the discharge port of the second passage. SUMMARY OF THE INVENTION It is the object of the present invention to provide a fluid-treating apparatus in which a level of purification within the sphere of influence of the fluid treatment apparatus can be further increased. According to the present invention this object is solved by providing a fluid-treating apparatus comprising a nozzle arrangement, said nozzle arrangement comprising a fluid suction passage having a cone-shaped suction port and a plurality of annular fluid discharge passages stacked outside the fluid suction passage so as to surround the suction port and having two or more fluid discharge ports, a fluid drawn toward the suction passage being sheathed in a film of the fluid discharged from the two or more fluid discharge ports, said nozzle arrangement being connected to a fluid treating device including a fan, said fluid treating device being adapted to treat the fluid drawn from the suction passage of the nozzle arrangement and to discharge the treated fluid to the discharge passages together with fluid drawn in through a further suction port from outside of the fluid treating device, a ratio ψ=Qs/Qd of a flow rate Qs of the fluid drawn into the suction passage and a flow rate Qd of the fluid discharged from the two or more fluid discharge passages is set to be 1 or less, and a flow velocity of the fluid discharged from each of the two or more fluid discharge ports is set such that it decreases sucessively toward the outermost discharge port, to thereby form a cone shaped air curtain surrounding an interior drawing-in zone, wherein said air curtain has a flow velocity distribution in which the flow velocity decreases from the interior drawing-in zone toward the outside. According to the invention this object is also solved by providing a fluid-treating apparatus comprising: a partition member, a first fan mounted on one side of the partition member, a first fluid passage having a first suction port communicating with the suction side of the first fan and a first discharge port communicating with the discharge side of the first fan, the first discharge port being located around the first suction port, the first fluid passage extending from the first suction port to the first discharge port through the first fan, a second fan mounted on the other side of the partition member, a second fluid passage having a second suction port communicating with the suction side of the second fan and a second discharge port communicating with the discharge side of the second fan, the second discharge port being located around the first discharge port, thereby forming a nozzle arrangement together with the first suction port, the second fluid passage extending from the second suction port to the second discharge port through the second fan, a fluid-treating device mounted in the first fluid passage, whereby the flow rate of the fluid discharged from the discharge ports being set larger than the flow rate of the fluid drawn into the first suction port, and the flow velocity of the fluid discharged from each of the discharge ports is set such that it decreases sucessively toward the outermost discharge port, to thereby form a cone shaped air curtain surrounding an interior drawing-in zone, wherein said air curtain has a flow velocity distribution in which the flow velocity decreases from the interior drawing-in zone toward the outside. In a further embodiment of this apparatus, the fluid-treating device is a filter for cleaning air. In a yet other embodiment of the invention, the fluid-treating device is a heat exchanger. In accordance with the present invention, the thickness of the film of the fluid discharged from the discharge passages is increased. In addition, the difference of velocity between this discharged fluid and the fluid outside the local space is made small. Hence, mixing of the discharged fluid and the fluid outside the local space is suppressed. Other objects and features of the invention will appear in the course of the description thereof which follows. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1(A) is a cross-sectional view taken along line A-A of Fig. 1(B); Fig. 1(B) is a perspective view of a fluid nozzle arrangement according to the invention; Fig. 2 is a view showing the pattern of flow created by the nozzle arrangement shown in Figs. 1(A) and 1(B); Fig. 3 is a graph in which the cleanliness inside a local space is plotted against time for the case in which the suction nozzle shown in Figs. 1(A) and 1(B) is used and for the case in which the art suction nozzle shown in Fig. 8 is used; Fig. 4 is a schematic cross sectional view of a fluid-treating apparatus according to the invention; Fig. 5 is a schematic cross sectional view of another fluid-treating apparatus according to the invention; Fig. 6 is a vertical cross sectional view of a further fluid-treating apparatus according to the invention; Fig. 7 is a vertical cross sectional view of a yet other fluid-treating apparatus according to the invention; and Fig. 8 is a schematic cross sectional view of a fluid-treating apparatus according to the Japanese Patent application Ser. No. 169893/1990. DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1, there is shown a fluid nozzle arrangement embodying the concept of the present invention. The nozzle, generally indicated by reference numeral 20, comprises an inner member 21, an intermediate member 22, and an outer member 23. The inner member 21 consists of a cylindrical portion 21a and a conical portion 21b which is connected with the front end of the cylindrical portion 21a and spreads outwardly. Similarly, the intermediate member 22 is composed of a cylindrical portion 22a and a conical portion 22b. The outer member 23 consists of a cylindrical portion 23a and a conical portion 23b. These members 21, 22, and 23 are slightly spaced from each other and disposed coaxially in this order. Thus, a suction passage 24 for sucking in fluid is formed inside the inner member 21. A first annular discharge passage 25 for discharging fluid is defined between the inner member 21 and the intermediate member 22. A second annular discharge passage 26 for discharging fluid is formed between the intermediate member 22 and the outer member 23. The first discharge passage 25 and the second discharge passage 26 are stacked on the outside of the suction passage 24 in this order so as to surround the suction passage 24. The conical portions 21b, 22b, and 23b are tilted at the same angle of α to the stream line P of the fluid drawn into the suction passage 24. This angle α is set to 45° to 90°. The flow rate Q S of fluid drawn into the suction passage 24 is set larger than the flow rate Q D of fluid discharged from the first discharge passage 25 and from the second discharge passage 26. The flow velocity inside the second discharge passage 26 is made lower than the flow velocity inside the first discharge passage 25. When air is blown obliquely downwardly at a given velocity from the first discharge passage 25 and from the second discharge passage 26 as shown in Fig. 2, the annular air flow AC becomes thick. A local space AZ surrounded by this air flow AC is formed inside a room or chamber RO. The air inside the local space AZ is drawn into the suction passage 24 as indicated by the blank arrow. Fig. 3 shows the manner in which the dimensionless cleanliness C inside the local space AZ varies with time. In Fig. 3, curve a indicates the cleanliness obtained when the suction nozzle shown in Fig. 8 is used and the ratio of flow rate ψ is 1.0. Curves b, c, and d indicate cleanlinesses derived when the suction nozzle 20 according to the present invention is used. Curve b indicates the cleanliness obtained when the ratio of flow rate ψ is 0.67. Curve c indicates the cleanliness obtained when the ratio of flow rate ψ is 0.5. Curve d indicates the cleanliness obtained when the ratio of flow rate ψ is 0.5 and the widths of the first and second discharge passages 25, 26 are doubled compared with the cases of curves b and c. As can be seen from Fig. 3, the dimensionless cleanlinesses C obtained when the novel suction nozzle 20 is used as indicated by curves b, c, and d are much better than the dimensionless cleanliness C obtained when the suction nozzle shown in Fig. 8 is employed as indicated by curve a. Where the novel suction nozzle is used, as the ratio of flow rate ψ is reduced, the dimensionless cleanliness C is improved. This is explained as follows. Diffusion of the concentration of contaminants due to mixing of the air flow AC and the surrounding air increases in proportion to the velocity gradient of the air flow AC, and this diffusion is suppressed with increasing the thickness of the film of the air flow AC. Therefore, reductions in the flow velocity of the outer discharge passage 26 decrease the velocity gradient of the air flow AC. Also, the thickness of the air flow AC is increased. Referring next to Fig. 4, there is shown a fluid-treating apparatus in which the suction nozzle 20 described above is connected with an air cleaner 31 via a duct 30. When a fan 32 incorporated in the air cleaner 31 is driven, the air blown from this fan passes through outer annular fluid passages 33 and 34 formed in the multiple duct 30 and then flows through the first discharge passage 25 and the second discharge passage 26 in the suction nozzle 20. Then, the air is blown into the room RO. The air inside the local space AZ surrounded by the air flow AC is drawn into the suction passage 24 of the suction nozzle 20, passes through a passage 35 formed in the center of the multiple duct 30, and enters the air cleaner 31. The air then flows downwardly through a filter 36, a duct collecting material 37, and a deodorant 38. In this process, the air is cleaned. The air is again drawn in by the fan 6 together with the air drawn into the cleaner 31 from a suction port 39. The process described thus far is repeated. Referring to Fig. 5, there is shown a fluid-treating apparatus in which the suction nozzle 20 described above is connected with an air conditioner 41 via the duct 30. When a fan 42 mounted within the air conditioner 41 is driven, the air discharged from the fan passes through a heat exchanger 43. In this process, the air is heated or cooled so as to be conditioned. The conditioned air passes through the outer annular passages 33 and 34 inside the multiple duct 30, flows through the first discharge passage 25 and the second discharge passage 26 in the suction nozzle 20, and passes into the room RO. The air inside the local space AZ surrounded by the air flow AC is drawn into the suction passage 24 of the nozzle 20 and enters the air conditioner 41 through the central passage 35 in the duct 30. The air is then again drawn in by the fan 42 with the air drawn into the conditioner 41 from a suction port 44. The process described thus far is repeated. Referring to Fig. 6, there is shown a fluid-treating apparatus in which a suction nozzle is integral with a fluid-treating device. The inside of a casing 50 is partitioned into an upper portion and a lower portion by a partition member 51. A first centrifugal fan 52 is mounted below the partition member 51. A second centrifugal fan 53 is disposed above the partition member 51. These fans 52 and 53 are rotated by an electric motor 54 held to the partition member 51. A second suction port 55 is formed in the outer periphery of the casing 50 near the top of the casing. A first suction port 56 is formed in the center of the lower portion of the casing 50. An annular first discharge port 57 is formed around the first suction port 56. A second discharge port 58 is formed outside, and adjacent to, the first discharge port 57. The first suction port 56 is in communication with the suction side of the first centrifugal fan 52 via both a HEPA (high efficiency particulate air) filter 64 and a bell-mouth 65. The first discharge port 57 is in communication with the discharge side of the first centrifugal fan 52. Thus, a first fluid passage 66 which extends from the first suction port 56 to the first discharge port 57 via the first centrifugal fan 52 is formed. The second suction port 55 is in communication with the discharge side of the second centrifugal fan 53 via a HEPA filter 60 and a bell-mouth 61. The second discharge port 58 is in communication with the discharge side of the second centrifugal fan 53. In this way, a second fluid passage 62 is formed which extends from the second suction port 55 to the second discharge port 58 via the second fan 53. When the centrifugal fans 52 and 53 are driven by the motor 54, the air inside the room is forced into the casing 50 from the second suction port 55 via a suction grille 59. The air then flows through the HEPA filter 60, so that the dust is removed. Subsequently, the air is drawn in by the second centrifugal fan 53 while guided by the bell-mouth 61. The air blown by the fan 52 passes through the second fluid passage 62 and is blown into the room from the second discharge port 58. At the same time, the air inside the local space AZ passes from the first suction port 56 into the casing 50 via a suction grille 63. The air then flows through the HEPA filter 64, whereby the dust is eliminated. The air is thereafter drawn in by the first centrifugal fan 52 while guided by the bell-mouth 65. The air blown by the fan 52 passes through the first fluid passage 66 and is blown out from the first discharge port 57. Referring to Fig. 7, there is shown another fluid-treating apparatus. This is similar to the fluid-treating apparatus shown in Fig. 6 except that a heat exchanger 67 is mounted in the first fluid passage at the exit of the first centrifugal fan 52. Air is caused to pass through the heat exchanger 67. In this manner, cooled or heated air is blown out of the first discharge port 57 to cool or warm the local space AZ. In the above embodiments, air is drawn in and blown out. What is drawn in and blown out is not limited to air; it may be any other gas or liquid. Also in the above embodiments, two layers of discharge passage are provided. Three or more layers of discharge passage may be formed, in which case the flow velocity of the fluid is reduced successively toward the outermost layer. Though the suction passage is circular in cross section and the discharge passages are annular in the description made above, elliptical, polygonal, and any other desired shapes may be adopted. In accordance with the present invention, the flow rate of the fluid discharged from the discharge passages is set larger than the flow rate of the fluid drawn into the suction passage. The flow velocity in each of the stacked discharge passages is so set that it decreases successively in going toward the outermost discharge passage. Therefore, the thickness of the film of the fluid discharged from the discharge passages is increased. Furthermore, the velocity difference between the discharged fluid and the fluid outside the local space is reduced. Consequently, mixing of the discharged fluid and the fluid outside the local space is suppressed. The cleanliness of the fluid inside the local space and other characteristics can be improved by connecting this fluid suction nozzle with a fluid-treating device.

Claims: A fluid treating apparatus comprising a nozzle arrangement (20), said nozzle arrangement (20) comprising a fluid suction passage (24) having a cone-shaped suction port (21b) and a plurality of annular fluid discharge passages (25,26) stacked outside the fluid suction passage (24) so as to surround the suction port (21b) and having two or more fluid discharge ports, a fluid drawn toward the suction passage (24) being sheathed in a film of the fluid discharged from the two or more fluid discharge ports, said nozzle arrangement (20) being connected to a fluid treating device (31,41) including a fan (32), said fluid treating device (31,41) being adapted to treat the fluid drawn from the suction passage (24) of the nozzle arrangement (20) and to discharge the treated fluid to the discharge passages (25,26) together with fluid drawn in through a further suction port (39,44) from outside of the fluid treating device (31,41), a ratio ψ=Qs/Qd of a flow rate Qs of the fluid drawn into the suction passage (24) and a flow rate Qd of the fluid discharged from the two or more fluid discharge passages (25,26) is set to be 1 or less, and a flow velocity of the fluid discharged from each of the two or more fluid discharge ports is set such that it decreases sucessively toward the outermost discharge port, to thereby form a cone shaped air curtain surrounding an interior drawing-in zone, wherein said air curtain has a flow velocity distribution in which the flow velocity decreases from the interior drawing-in zone toward the outside. A fluid treating apparatus comprising: a partition member (51); a first fan (52) mounted on one side of the partition member (51); a first fluid passage (66) having a first suction port (56) communicating with the suction side of the first fan (52) and a first discharge port (57) communicating with the discharge side of the first fan (52), the first discharge port (57) being located around the first suction port (56), the first fluid passage (66) extending from the first suction port (56) to the first discharge port (57) through the first fan (52); a second fan (53) mounted on the other side of the partition member (51); a second fluid passage (62) having a second suction port (55) communicating with the suction side of the second fan (53) and a second discharge port (58) communicating with the discharge side of the second fan (53), the second discharge port (58) being located around the first discharge port (57), thereby forming a nozzle arrangement together with the first suction port (56), the second fluid passage (62) extending from the second suction port (55) to the second discharge port (58) through the second fan (53); a fluid-treating device mounted in the first fluid passage; whereby the flow rate of the fluid discharged from the discharge ports (57,58) being set larger than the flow rate of the fluid drawn into the first suction port (56), and the flow velocity of the fluid discharged from each of the discharge ports is set such that it decreases sucessively toward the outermost discharge port, to thereby form a cone shaped air curtain surrounding an interior drawing-in zone, wherein said air curtain has a flow velocity distribution in which the flow velocity decreases from the interior drawing-in zone toward the outside. The fluid-treating apparatus of claim 2, wherein said fluid-treating device is a filter (64) for cleaning air. The fluid-treating apparatus of claim 2, wherein said fluid-treating device is a heat exchanger (67).

Inventors: HASEGAWA NORITAKA, KONDO FUMIO, YAMANAKA TOSHIHIKO, YOSHIDA TETSUO, HASEGAWA, NORITAKA, KONDO, FUMIO, YAMANAKA, TOSHIHIKO, YOSHIDA, TETSUO, Hasegawa, Noritaka, c/o Churyo Engineering K. K., Kondo, Fumio, Nagoya Techn. Instit. of Mitsubishi, Yamanaka, Toshihiko, Nagoya Techn.Inst. of Mitsub., Yoshida, Tetsuo, Hiroshima Mach. Works of Mitsub.
Applicants: CHURYO ENG, MITSUBISHI HEAVY IND LTD, CHURYO ENGINEERING KABUSHIKI KAISHA, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1992
Main classification: F24F3
IPC codes: F24F3, F24F9, F24F1, F24F13