US1835284A - Circulating device for hot water heating systems - Google Patents

Description

1931- A. E. CROWHURST 5,

CIRCULATING DEVICE FOR HOT WATER HEATING SYSTEMS Filed Aug. 5, 1927 INV'ENTDR Patented Dec. 8, 1931 PATENT OFFICE ALBERT ERNEST C'RDWHURST, OF HUMBER BAY, ONTARIO, CANADA.

GIRGULATING- FOR HOT WATER HEATING SYSTEMS Application filed August 1927. Serial No. 210,852.

This invention relates to impellers and more particularly to the type for accelerating, when desired, the circulation of the water in a gravity hot water heating system.

Heretofore it has been found in some'cases that the water was circulated very slowly, in other cases the water flowed backwards through the impeller inv the direction opposite to that of the thrust of the impeller blades, and in other cases the water did not circulate in either direction.

My object is to provide an impeller of simple construction which will overcome the above objectionable features and which will be very eflicient in operation.

I attain my object by pivoting the blades on a hub secured .to a rotatable shaft so that the blades will swing radially of the shaft. Stops are provided for determining the inoperative and operative positions of the blades. The latter are connected by links with a sleeve slidable on the hub. A spring tending to swing the blades to their inoperative position with their center lines substantially parallel to the axisof the shaft is disposed on the sleeve and has one end in engagement therewith and the other end in engagement with an abutment on the shaft. The connections between the links and the blades are so arranged that the leverage ,is respectively increased and decreased in direct proportion to the decrease and increase vin compression of the spring. The are through which each of the blades passes fromits inoperative to its operative position is less than that subtending a right angle, which arrangement directs the flow of water by centrifugal action in the same direction as the flow of water by the thrust action of the blades. The constructions are hereinafter more fully, described and are illustrated in the accompanying drawings in which Fig.1 is a diagrammatic view of an .impeller mounted in a casing connected in the return pipe of a gravity hot water system and showing the blades extending at right angles to the axis of the drive shaft;

. Fig. 2 is aview similar to Fig. 1 except the that shown in Fig. 1;

blades are shown at an angle different from.

Fig. 3 a horizontal section of a casing showing my improved impeller in plan therein in its operative position;

Fig. 4 a plan of the impeller shown in Fig. 3 showing it in its inoperative position;

Fig. 5 an end elevation in full lines of the impeller shown in Fig. 3 and showing an end view of Fig. 4 in dotted lines; and

Fig. 6 a side elevation, partly broken away, of Fig. 4.

In the drawings like numerals of reference indicate corresponding parts in the different figures.

1 is a cylindrical casing provided with inlet and outlet flanges 2 and 3 adapted to be connected in the return pipe of a circulating system. 4 is a shaft extending into the casing and journalled in the bearing 5 and in the gland of the stuffing box 6.

A hub 7 secured to the inner end of the shaft is provided with a bifurcated end 7 which carries two pins 8. These pins are located on opposite sides of the center line of the shaft and substantially at right angles thereto. On each pin is journalled a bearing block 9 to which is secured a. fan blade 10 so that the blades will swing radially of the shaft.

The bearing'blocks 9 are each provided with a lug '9. Outhe hub 7 is slidably mounted a sleeve 11 which is provided with lugs 11*. Links 12 each having one end p-ivotally connected with a lug 9 and the other /end connectedwith a lug 11 connect the fan blades with the sleeve so that both blades will be moved simultaneously. A compression spring 13 disposed on the sleeve 11 engages the lugs 11 andan abutment 14 to tend to swing the blades to an inoperative position with their center lines substantially parallel to the axis of the shaft. In this position the blades which are formed of flat sheet metal are substantially parallel to one another as shown in Fig?!) so they will not obstruct the flow of wa er by gravity. The inoperative position of the blades is determined by limiting the axial movement of the sleeve in one direction and this may be done by forming a shoulder 7" on the hub 7 for engaging the sleeve lugs 11". l

When in the inoperative position the blades lie close to one another and if they fully blanket one another, they will not open out when rotated, but it will be noted that one side edge of each projects past the adjacent side edge of the other, so that when the impeller is rotated with the parts of the blades thus exposed facing the direction of rotation, a thrust is produced which will start the movement of the blades to the operative position.

Impellers having blades directed radially of the shaft and at right angles thereto, as

shown in Fig. 1, do not operate efficiently. It has been found in practice that with this type of impeller the centrifugal force of the water caused a flow lengthwise of the blades of suflicient magnitude to overcome the forward thrust of the blades. Due to the thrust of the impeller and to the restricted outlet flange 3 the pressure is greater in the outlet flange 3 and in the portions B of the casing adjacent the outlet flange than in the portions C of the casing. From this it is obvious that the water thrown outward by centrifugal action will meet with less resistance at the portions C behind the blades than at the portions B and will thus flow backwards, as indicated in Fig. 1. To overcome the above objectionable feature I limit the arc through which each of the blades passes from its inoperative to its operative positions so that it is less than that subtending a right angle, as shown in Figs. 2 and 3. This results in the flow of water lengthwise of the blades being directed towards the outlet flange 3 and towards the flow caused by the thrust of the impeller whereby the first mentioned flow assists the second mentioned flow instead of opposing it. The flow caused by the thrust action of the impeller is thus directed towards the restricted outlet flange to overcome the increased back pressure at this point. Lips 9 formed on the blocks 9 are adapted to engage shoulders 7 on the hub end 7 to determine the operative position of the blades.

It will be noted that the lugs 9 extend laterally from the blocks 9 substantially at right angles to the center lines of the blades whereby the lugs, when the blades are moved to their operative position, are swung inwardly towards imaginary lines drawn between the centers of the lugs on the sleeve and the pins to vary the leverage of the link connections with the lugs 9 inversely to the compresion of the spring 13.

The blades are adapted, when the shaft is rotated, to be swung outwardly against the compression of the spring 13 by the thrust action of the water against the adj 'acent faces of the blades and by centrifugal force. The

corners 10 of the blades are rounded off andthe inner ends of the blades are staggered, as shown, to facilitate the opening of the blades by the thrust action of the water. To

ensure the starting movement of the blades towards their operative position by the thrust action of the water the other corners 10 of the blades are bent toward the adjacent corners 10 whereby the water, when the blades are rotated will engage the pockets formed by the bent corners to force the blades away from one another. While the angle between each blade and its pin 8 remains constant, the pitch of the impeller is increased when the blades are moved towards their operative position. With the hereinbefore mentioned link and sleeve connections 11 and 12, it is impossible for one blade to move independently of the other blade.

What I claim as my invention is:

1. An impeller adapted to force water in the normal direction of flow through a gravity hot Water heating system comprising a rotatable shaft; substantially straight fan blades in permanent connection with the shaft but pivotally carried thereby so as to swing radially thereof from their operative position to an inoperative position in which they trail from their pivots in the direction of flow in proximity to and parallel to one another and with one side edge of each blade p'roject ing past the adjacent side edge of the other blade, the blades being adapted when the shaft is rotated to be swung outward by the thrust resistance of the water and centrifugal force; means limiting the outward swing of the blades to determine their operative position; and means tending to swing the blades to their inoperative position comprising a sleeve axially movable on the shaft and provided with lugs, a lug carried by each blade, a link connecting a lug on the sleeve with a lug on a blade, an abutment on the shaft, and a spring disposed on the sleeve and having one end in engagement with the abutment and the other end in engagement with parts on the sleeve.

2. An impeller adapted to force water in the normal direction of flow through a gravity hot water heating system comprismg a rotatable shaft; substantially straight an blades in permanent connection with the shaft but pivotally carried thereby so as to swing radially thereof from their operative POSI- tion to an inoperative position in which they trailfrom their pivots in the direction of flow in proximity to and parallel to one another, the blades being adapted when the shaft is rotated to be swung outward by the thrust resistance of the water and centrifugal force; means limiting the outward swing of the blades to determine their operative position; and means tending to swing the blades to their inoperative position comprising a sleeve axially movable on the shaft and provided with lugs, a lug carried by each blade, a link connecting a lug on the sleeve with a lug on a blade, an abutment on the shaft, the lugs being so positioned that the leverage of the blades on the linlis increases as'the blades swing from their inoperative to their operative position to compensate for the increased tension of the spring, and a spring disposed on the sleeve and having one end in engagement with the abutment and the other end in engagement with parts on the sleeve.

3. n impeller adapted to force water in the normal direction of flow through a gravity hot water heating system'comprising a rotatable shaft; substantially straight an blades pitched from end to end and in permanent connection with the-shaft but pivotally carried thereby so as to swing radially thereof from their operative position to an inoperative position in which they trail from their pivots in the direction of ow in proxv imity to and parallel to one another, the

blades being adapted when the shaft is rotated to be swung outward by the thrust resistance of the water and centrifugal force; and means limiting the outward swing of the blades so that when in their operative position their center lines incline forwardl in the direction of flow and their thrust is' 'agonal to the axis of the impeller. v

Signed at Toronto, Canada, this 23rd day of July, 1927. a I

ALBERT ERNEST CROWHURST.

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