US1921153A

US1921153A - Motor driven blower unit

Info

Publication number: US1921153A
Application number: US186287A
Authority: US
Inventors: Joseph M Cantwell
Original assignee: Individual
Current assignee: Individual
Priority date: 1927-04-25
Filing date: 1927-04-25
Publication date: 1933-08-08
Anticipated expiration: 1950-08-08

Description

- Aug. 8, 1933. J. M. CANTWELL MOTOR DRIVEN BLOWER UNIT Filed April 25, 1927 M INVENTOR.

I a .7 8W a/ A ZZ A TTORNE Y.

Patented Aug. 8, 1933 MOTOR DRIVEN BLOWER UNIT Joseph M. Cantwell, Albany, N. Y.

Application April 25, 1927.

1 Claim.

The present invention relates to blowers, and particularly to devices of this character adapted for creating a forced draft in furnaces or the like. and for general use where it is desirable to deliver a comparatively large volume of air in a highly diffused state at comparatively low pressure.

Where blowers of the present type are used for plying air to the plenum chamber of a furve or the ke, it is practically impossible to maintain a u; form rate of combustion over the entire grate area. These blowers merely create a unidirectional movement of a column of air which, when it enters the plenum chamber, ap-

parently does not create or maintain therein a amount of air, and thus effect an ever increas ing variation in the rate of combustion in the difiercnt zones of the furnace.

With these disadvantages of the present blowers in mind, the primary object of my invention is to provide a device of this character which will deliver a large volume of air in such a way that, after leaving the draft tube of the blower, it will become rapidly diffused and intermixed with the surrounding air. Another objectis to provide a blower which will deliver a large volume of air to the plenum chamber of a furnace or the like, and in such a way that the development of hot spots in the fuel bed will be substantially prevented. Another object is to provide a blower which will deliver a greater volume of air with less power input than is possible with blowers of the present type. A further object is to provide, in connection with a blower of this general character, an automatically operated check damper which will prevent the back-flow of air through the draft tube when the blower is not in operation.

With these objects in view, my invention includes the novel elements, and the combinations and arrangements of elements described below and illustrated in the accompanying drawing, in which Fig. 1 is a vertical sectional view through the blower with the motor in elevation;

Fig. 2 is a sectional view on line 22 of Fig. 1; and

Serial No. 186,287

Fig. 3 isa view. of the fan.

Referring to the drawing, 10 indicates a caswhich may be constructed in any suitable manner to provide merely a carrier for the fan, ll, or to also provide asupport for a motor, 12, and a draft tube for the blower, as shown. In the embodiment illustrated, an electric motor, 12, is bolted or otherwise secured to the intake end of the casing so that its shaft is substantially coaxial with the axis of the tube, and afan, 1]., pinned or keyed directly to the motor shaft. The blades of the fan, 11, are preferably, though not necessarily, of the type shown and terminate in close proximity to the wall of the casing.

Within the casing and on the discharge side of the fan, or, in other words, Within What is ordinarily termed the draft tube, are a plurality of separate elements, 13, which are designed to give a whirling motion to the column of air impelled by the fan. These elements are carried by the casin and preferably may be cast as an integral part thereof. They might, perhaps, be described as fin-like projections which extend inwardly only a comparatively short distance from the inner periphery of the casing, so that the central portion of the draft tube is unobstructed, and are downwardly inclined or pitched in the direction of rotation of the fan to provide guides for changing the otherwise normal axial movement of the air column to a spiral or whirling movement. The provision of the fins or blades makes the entire area of the blades of the propeller and the blower more effective. The surfaces of these elements against which the air impingesmay be plane, helicoidal or otherwise so long as they are adapted to impart a whirling motion to the air, and generally of any pitch desired, although too fiat a pitch will cause a slight puff back through the intake at high fan speeds and is, therefore, not desirable.

It is well known that the fan, in addition to producing a forward or driving movement of the air, also produces a whirling movement. By placing the fins in the draft tube or casing at the points illustrated in the drawing, that is, with theirupper ends just below the fan, and extending them only a short distance (measured axially of the tube), they intercept or pick off the air as it leaves the fan and modify the direct forward movement thereof by imparting a decided whirling movement to the air column, thus augmenting the whirling movement established by the fan. This whirling movement, densifies the air in the outer part of the column and rarefies the air in the center so that a marked increase in the efiiciency of the blower is noted. When the whirling column of air passes the discharge opening in the draft tube and is no longer laterally confined, it becomes highly diffused, spreading out in all directions and thus rapidly intermixing with the air into which it is projected.

In order to protect both the fan and the motor from the detrimental effect of dust or other foreign matter from the ash pit, which usually circulates incident to the opening of the door of the ash pit, I have provided an automatically operable damper, 14, arranged within the draft tube or casing, 10, so that access may be had to the ash pit without subjecting the fan or motor to the effect of dust. This damper is pivoted off center, as at 15, and carries a counter weight.- 16, so that it will automatically gravitate to its normal closed position when the motor, 12, is stopped and the current of air through the casing ceases. The damper should fit rather loosely at the sides near the ends of the pivotal axis and this axis should be quite close to the center of the damper, as shown. When the blower is in use, the current of air passing through the casing is utilized to maintain the damper, 14, fully opened, but when it is desired to open the door of the ash pit, the motor is first stopped, thereby allowing the damper to automatically gravitate to a closed position for the purpose stated.

While I have described my invention in its preferred embodiment it is to be understood that the Words which I have used are words of description rather than of limitation and that changes within the purview of the appended claim may be made Without departing from the true scope and spirit of my invention in its broadest aspects.

What I claim is-- In a blower, including a rotating fan of the propeller type, a tubular member through which the air is impelled by the fan characterized by having a plurality of stationary projecting elements inclined to the axis of said member and disposed about the inner surface thereof from JOSEPH M. CANTWELL.