GB2079372A

GB2079372A - Axial flow fans

Info

Publication number: GB2079372A
Application number: GB8022541A
Authority: GB
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1980-07-09
Filing date: 1980-07-09
Publication date: 1982-01-20
Also published as: GB2079372B

Abstract

A ventilation fan includes a motor (4) for driving rotatable fan blades (5), the motor being mounted in a case on a supporting frame (3) and a front cover (11) detachably mounted on the case, the cover and case having portions (10a, 13) for engagement with each other and detent means for (14a, 15) limiting movement of the cover to a predetermined distance if vibration causes the cover to become disengaged from the case. The cover is removed to enable cleaning of the ventilator and shutter blades (6) are opened when a lever (8) is moved in response to operation of the motor switch. <IMAGE>

Description

SPECIFICATION Exhaust fan This invention relates to an exhaust fan and more particularly to a fan having improved engaging means between the case and a front cover to prevent the cover from falling from the case.

In an exhaust fan, for example, a ventilator for exhausting air from a kitchen, it is necessary to mount the front cover detachably on a case so that the cover can be cleaned. However, in prior exhaust fans another special connecting element is necessary to connect the cover with the case tightly to prevent the cover being loosened and falling off as a result of the vibration of the drive or because of wear of the material. However, prior exhaust fans have the drawback that assembly is very difficult because the operator must connect the cover and the case by a specific connecting element whenever he wants to attach the cover to the case and the operator sometimes loses the connecting element because it is not integral with the case or the cover.

This invention seeks to provide an exhaustfan which has improved means for attachment of the cover.

This invention also seeks to provide an exhaust fan which avoids the problem of the cover becoming loose and falling off, without the necessity of a special connecting element.

Accordingly the present invention provides an exhaust fan including a casing, a front cover detachably mounted on said case, inter-engaging means on said cover and said case to hold the cover in engagement with the case, and detent means adapted to limit movement of the cover from the case.

Some embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is a sectional view of an exhaust fan comprising a first embodiment of this invention; Figure 2 is a partially englarged sectional view of the fan of Figure 1; Figure 3 is a partially enlarged perspective view of the fan of Figure 1; Figure 4 is a sectional view of the engaging means of the fan of Figure 1; Figure 5 is a sectional view of a second type of fan according to the invention; Figure 6 is an exploded view of the fan of Figure 5; Figures 7and 8 are partially enlarged sectional views of the engaging means of the fan of Figure 5; Figure 9 is a rear perspective view of the front cover of a third type of fan according to the invention; and Figure 10 is a partially enlarged view of the engaging means of the fan of Figure 9.

Referring first to Figures 1 to 4, a case 1 is adapted to be mounted in an opening 2 of a wall W. A frame 3 for supporting a drive element, such as motor 4 is secured inside case 1. Fan blades 5 are mounted on a shaft (not shown) of motor 4. Three shutter blades 6 of a shutter 7 are located in the outer opening of case 1 and are movably mounted on a connecting lever 8.

Connecting lever 8 moves up and down in response to off and on movement of the ON-OFF control switch of motor 4 respectively. Shutter 7 opens opening 2 of case 1 when connecting lever 8 is moved downwardly and closes opening 2 of case 1 when connecting lever 8 is moved upwardly. Four flanges 9 extend outwardly at right-angles from the peripheral edge portion of the inside opening of case 1. Hooks 10, each having a convex portion 10a formed on the tip of one of the top and bottom flanges 9, extend at right angles to the flanges, towards the inside of the room. A front cover 11 is formed integrally with a bellmouth 12 which is made of plastic material. Protrusions 13 are integrally formed on the top and bottom edges of cover 11. In this way cover 11 is detachably secured to flange 9 of case 1 by elastically engaging each convex portion 1 0a and the corresponding protrusion 3.The fan blades 5 are surrounded by bellmouth 12 because the bellmouth 12 extends into the inside opening of case 1 when cover 11 is engaged with case 1.

Bellmouth 12 is formed in a substantially cylindrical shape which is tapered from the inside portion of the room to the outside portion thereof. A supporting projection 14 is integrally formed with the bottom portion of the outside opening of bellmouth 12 and has a horizontally extending tip. An upward hook 14a is integrally formed on the tip of supporting projection 14. An arm 3b is upwardly formed by bending a part of lower portion 3a of frame 3 and is secured to the inner surface of a bottom wall 1 a. An aperture 15 is formed in arm 3b. When cover 11 is engaged with case 1, hook 14a is located below the upper edge of hole 15 and behind arm 3b, but does not engage with the upper edge of hole 15 as long as all the protrusions 13 are engaged with the corresponding hooks 10. (see Figure 2).Projection 14 has two parallel ribs 16 on the undersurface thereof which are adapted to act as a fulcrum under the bottom of bell mouth 12 as explained below. The lower edge of rib 16 has a step 16a whose profile substantially matches the form of bottom wall 1 a and there is normally a small clearance between them.

The operation of the invention will now be explained. The operator can take off the cover 11 when he wants to clean the ventilator by pulling cover 11 towards the inside oCthe room. After cleaning is finished, remounting is as follows. After setting the rear edge of rib 16 on bottom wall 1a of case 1 by pushing cover 11 inward, rib 16 slides on the surface of bottom wall la. The surface of bottom wall 1a guides supporting projection 14 into hole 15 and protrusion 13 is elastically engaged with convex portion 1 0a of hook 10 because supporting projection 14 is positioned lower than the lower edge of arm 3b and just passes through hole 15. Thus, cover 11 is attached to case 1.

If cover 11 is not securely attached to case 1 or becomes loose owing to wear of the materials or vibration of the drive, then, cover 11 tilts in the direction indicated by the arrow A around the point P as fulcrum (Figure 4) because ribs 16 of bellmouth 12 contact the bottom wall 1 a of case 1. The movement of cover 11 thus causes the engagement of support ing projection 14 and arm 3b and cover 11 is held to case 1 by supporting projection 14 (see Figure 4).

The fall of cover 11 can avoid the engagement of top hook 10 and top protrusion 13 if the engagement of bottom hook 10 and bottom protrusion 13 comes off. In the foregoing embodiment, cover 11 is easily able to move because rib 16 covers the clearance between bell mouth 12 and the surface of bottom wall 1a.

Figures 5 to 8 show the second embodiment of the invention. in this embodiment, an arm 3 extends downwardly from the inner surface of a top wall 1 b and has an aperture 5 with a cut away lower edge to form a groove 17, and the end portion of supporting projection 14 is bifurcated so that hook 14a comprises two portions 18. The width of groove 17 is less than the width of hole 15 and the combined width of portions 18 of supporting projection 14 is between the width of hole 15 and groove 17. The length Bof supporting projection, which projects to behind frame 3, is greater than the width C of convex portion 1 0a of hook 10. As cover 11 is attached to case 1, a clearance D between the edge of supporting projection 14 and the bottom of groove 17 is smaller than a clearance E between bell mouth 12 and fan blade 5.In this embodiment, the cover 11 does notfall even if the engagement of top hook 10 and top protrusion 13 comes off because portions 18 get into groove 17 before cover 11 falls and engage with the arm as length B is larger than width C.

Bellmouth 12 of cover 11 does not contact fan blades 5 because clearance D is smaller than clearance E.

Supporting projection 14 easily passes through hole 15 because portions 18 of supporting projection 14 are elastically deformable.

Figure 9 and Figure 10 show the third embodiment of the invention. In this embodiment, a pair of supporting projections 19 which each have a hook 20 are secured to frame 3 and arm 21 is secured to bellmouth 12 and is notched to permit the passage of supporting projection 19 into groove 23 via slot 22. Thus the cover 11 does not fall even if the top hook 10 becomes disengaged from protrusion 13 because the hooks 20 of supporting projections 19 engage with grooves 23.

Claims

1. An exhaust fan including a casing, a front cover detachabvly mounted on said case, interengaging means on said cover and said case to hold the cover in engagement with the case, and detent means adapted to limit movement of the cover from the case.

2. An exhaustfan according to claim 1,wherein said cover is arranged to tilt relative to the case with the lower portion thereof acting as a fulcrum.

3. An exhaust fan according to claim 2, wherein said engaging means includes a supporting projection which is mounted on one of said cover or said case and an arm which is mounted on the other thereof having a hole for permitting the insertion of said supporting projection and for limiting movement of said cover by the engagement of said supporting projection and said arm.

4. An exhaust fan according to claim 3, wherein said supporting projection is integrally molded with a bellmouth on the cover.

5. An exhaust fan according to claim 3 or 4, wherein said supporting projection further includes a hook formed on the tip thereof for engaging with said arm.

6. An exhaust fan according to claim 5, wherein said arm is mounted on the inner surface of the bottom wall of said case.

7. An exhaust fan according to claim 6, wherein said arm is integrally molded with a frame in the casing which supports a fan motor.

8. An exhaust fan according to claim 3 further including a fulcrum projection for inclining said cover.

9. An exhaust fan according to claim 8, wherein said fulcrum projection contacts the inner surface of the bottom wall of said case only in the event of disengagement of said case and cover.

10. An exhaust fan according to claim 9, wherein said fulcrum projection includes a rib extending in the set-reset direction of said cover to guide said cover relative to the inner surface of the bottom wall of said case.

11. An exhaust fan according to claim 5, wherein said arm is supported on the inner surface of the top wall of said case.

12. An exhaust fan according to claim 10, wherein said arm includes a groove which is continuously formed with said hole and is narrowerthan said hole, the width of said supporting projection being between the width of said hole and said groove.

13. An exhaust fan according to claim 10, wherein said arm is integrally molded with said frame.

14. An exhaust fan according to claim 3, wherein said arm is integrally molded with said bellmouth and said supporting projection is mounted on said case.

15. An exhaust fan according to claim 3, wherein said arm is integrally molded with said bellmouth and said supporting projection is mounted on said frame.

16. An exhaust fan substantially as herein described with reference to Figures 1 to 4 or Figures 5 to 8 or Figures 9 and 10 of the accompanying drawings.