US2005408A - Fan inlet guard and a method of manufacturing the same - Google Patents

Description

June 18, 1935 M. c. ALUN 2,005,408

FAN INLET GUARD AND A METHOD OF MANUFACTURING THE SAME Fil ed Feb. 21, 1955 I 28F, /6, Z INVEYNTOR L7 MATTHEW C1 ALLJN ATTORNEY Patented June 18, 1935 FAN INLET GUARD AND A METHOD OF MANUFACTURING SAME Matthew 'C.-Allin, Weston, Ontario, Canada,- assignor to Riley. Engineering & Supply Co. Ltd., Toronto, Ontario, Canada, a corporation of Canada Application February 21, 1933, Serial No. 657,824

8 Claims.

' Thisinv ention relates to a fan inlet guard and a method of manufacturing the same, the construction beingadapted to admit air to the interior of a fan housing, to protect the operator from injury, and to prevent foreign bodies from entering the fan and damaging therotating fan wheel.

It has been the practice heretofore to mount screens over the air inlets of fans, but the prior constructions have been expensive to manufacture, and it has been difficult toprovicle the desi'rable stream-lined air passage without complicating the construction and adding considerably to its cost. Furthermore, prior arrangements were lacking in strength and were frequently, distorted or broken and rendered unsightly by accidental blows. It is accordingly one object of the invention to provide a fan inlet guard which is simple and inexpensive tomanufacture and which is very strong in proportion to its weight.

- It is a further object of the invention to provide a' fan inlet guard which is attractive in appearance, andwhich .will lead the air smoothly and gradually into the center of the fan wheel without producing undesirableeddy currents in the airstream.

Itfisa' further object of the invention to provide a method of manufacturing fan inlet guards, which is simple and inexpensive to carry out in practice.

It is a further object of the invention to provide a method of manufacturing fan inlet guards which will produce a substantially integral and 35 very strong construction.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts and the steps of the process set forth in the specification 4 and covered by the claims appended hereto.

In accordance with my invention I provide a fan inlet guard comprising a perforated screen, preferably of wire-mesh, having its peripheral portion embedded in a cast metal frame. In the preferred construction, the frame is circular, and the screen is dished outwardly. The frame may be shaped to provide an inwardly-tapering stream-lined air passage. The construction is 50 manufactured by first providing a screen and then casting the metal frame into engagement with the peripheral portion of the screen. The screen is preferably dished before the casting operation, and it may be embedded in a core with the peripheral portion of the screen projecting outwardly beyond the core, molten metal bein poured around the core to form the frame.

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numeralsindicate like parts, V

Fig. 1 is a side elevation of a fan showing my improved inlet guard applied thereto;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a partial sectional view of a core box; and

Fig. 4 is a section through a mold ready for the pouring operation.

The embodiment illustrated comprises a fan housing It] provided with the usual scroll-shaped peripheral wall, and having a rotatable fan wheel l2 of well-known construction mounted therein. An inlet opening M (Fig, 2), preferably circular in shape, isprovided in the side wall of the housing ill to admit air to the fan wheel l2.

In order to prevent foreign bodies from reaching the fan wheel, and also guide the air into the interior of the wheel, I provide a perforated screen l6 havingits'peripheral portion embedded in a cast metal frame IT. The screen I6 is preferably circular in shape and formed of a rather coarse wire-mesh fabric. The frame I! is shown provided with an annular flange l8 which is riveted or otherwise secured to the fan housing In surrounding the opening M. The frame I! projects inwardly through this opening, and tapers smoothly and gradually towards the fan wheel to form a stream-lined air'passage. The screen I6 is dished outwardly, and hence has great strength to resist accidental blows.

In the manufacture of my improved fan inlet guard, I first provide the screen l6 and then cast the frame I! into engagement with the peripheral portion thereof. The screen is preferably bent into a dished shape prior. to the casting operation, by means of dies or. in any other suitable way.

In Fig. 3 I have shown a partial section through a core box which may be conveniently utilized in carrying out my novel process. This core box comprises a lower part 20 and an upper part 2|, these parts being shaped to provide the desired stream-lined form for the interior surface of the cast frame. An annular groove 22 is provided between the parts 20 and 2|, and in making the core the peripheral portion of the screen I6 is placed in this groove and the remainder of the screen is embedded in the core sand. Thus, when the core is completed, the peripheral portion of the screen will project outwardly beyond the core. It will be noted that the maximum internal diameter of the core box occurs intermediate the height of the upper part 2|, so that it will be necessary to form this part in a plurality of sections and withdraw each section in a radial direction, as will be understood by those skilled in the art.

Afterthc coreis completed it is placed in a mold and the frame I! is cast aroundthe core. In Fig. 4 I have shown a section through a mold ready for the casting operation. This mold, which may be prepared in accordance with the usual and well-known foundry practice, comprises a cope 24 and a drag 25 supported on a bottom board 25. The core 28, withithe screen:1i6-.embedded therein, is located in the moldobetween the cope and the drag, and an'annular moldcavity 29 surrounds the core. The peripheral portion of the screen projects into thiscavity. The mold is provided with the usual gate 3|, sprue 32, and pouring basin 33. Molten metal, such as iron, is poured into the mold to fillthe cavity 29 and form the annular frame I1. As this metalsolidifies it provides a firm and'substantially integral joint with the screen IS. The frame I! will shrink appreciably as it cools, and this shrinkage will simply cause the dishing of the screen to, be slightly more pronounced. There will be no buckling or irregular distortion of the screen, as would be the case if the screen were originally flat.

It will now be apparent that I have provided a fan inlet guard which is simple and inexpensive to manufacture and effective for the purpose intended. The construction is attractive in appearance, and provides a smooth stream-lined passageto conduct air into the fan wheel. The integral bond between the cast frame and the screen, together with the arched or dished form of the screen, provides. great strength without excessiveweight. Consequently the screen: will withstand'comparatively heavy blows withoutinjury ordistortion. My improved process of manufacture is simple and requires no expensive equipment. -It1 can be readily understood and-carried out 'by workmenof'ordinary skill in the foundry art.

"-Havingthus described myinvention, what I claim asnew' and desire to secure by Letters Patent is:

1; A fan inletguard comprising a dished circular wire-mesh screen having its peripheral portion embedded in an annular cast metal frame.

2. A fan inlet guard comprising an outwardly dished circular wire-mesh screen having its peripheral portion embedded in an annular cast metal frame, the frame being shaped to provide an inwardly-tapering stream-lined air,- passage.

3. A fan inlet guard comprising a dished circular wire-mesh screen having its peripheral portion embedded in an annular cast metal frame, the frame having an integral annular flange shaped to;engage the wall of a fan housing.

4. The method of manufacturing a fan inlet guard comprisingthe steps of providing a substantially circular wire-mesh screen, bending the screen into a dished shape, and casting an annular metal frame into engagement with the peripheral portion of the screen.

5. The method of manufacturing a fan inlet guard comprising the steps of providing a substantially circular wire-mesh screen, bending the screen into a dished shape, embedding thedished screen in a core with the peripheral. portionof the screen. projecting outwardly beyond the core,

placing the core in. a.mold.having an. annular cavity surrounding the core,.and .pouringmolten metal into the cavity to form an annular frame firmly united withthe screen.

6. A fan inlet guardcomprising anannular frame and a wire-meshscreen. extending. across the opening in the frame, the ends of the wires forming the screen beingembedded in they material of the frame, and the screen. being dished to relieve stresses caused byv temperature changes and to increase the strengthof the-screen.

7. A' fan inlet guard comprising an annular frame shaped to provide aninwardly-tapering stream-lined air passage, and a wire-mesh screen extending across the passage, the endsof the wires forming the screen being embeddedinthe material of the frame, and the screenbeing dished outwardly to relieve stresses causedloy temperature changes and to resist external blows.

8. A fan inlet guard comprising anannular frame having an integral. annular flange. shaped to engage the wall of a fan housing, and a.d.ished wire-mesh screen extending across ,theopening in the frame, the ends of thewiresformingthe screen being embedded in the material of the frame.

MATTHEW C. ALLIN.

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