US1093214A - Fan or blower system. - Google Patents

Description

N. L. SNOW.

PAN 0R BLOWER SYSTEM. APPLICATION FILED JULY 13,1912.

1,093,214. Patented Apr. 14, 1914 NORMAN L. SNOW, OF PLAINFIELD, NEW JERSEY.

FAN OR BLOWER SYSTEM.

Specification of Letters Patent.

Patented Apr. it, 191%.

Application filed July 13, 1912. Serial No. 709,130.

To all who-m, it may concern:

Be it known that I, NORMAN L. Snow, a citizen of the United States, residing at Plainfield, Union county, State of New Jersey, have invented certain new and useful Improvements in Fan or BlowerSystems, of which the following is a full, clear, and exact description.

My invention relates to new and useful improvements in fan or blower systems, and has for its object to provide a regulating fan or blower system in which the mass, 2'. c. the quantity in weight of the air or gas discharged, is automatically regulated.

Fans or blowers are extensively used for supplying air for ventilating and heating systems, such as driving the air to and through the rooms of a building, or through a mine or tunnel. They are also extensively used for supplying air for other purposes, as for instance where a blower drives the air through a bed of combustible, passageways, and other apparatus as in steam boiler plants, gas plants, baking and drying furnaces. In many of their uses, the resistance or head under which they work is wholly on the inlet or suction side, such as in exhausting foul air from a building, or a mine or tunnel; and in many instances the head is partially on the suction or inlet side and partially on the discharge side, as for example, in an induced draft system where the fan draws or sucks the gases from the furnace and discharges them out through the stack; or, in cold storage plants, where the fan circulates cold air, or in heating systems where the air is first drawn through a. heater and then driven to the rooms. Again, in many cases, the resistance is entirely on the discharge side, as when a fan or blower is used for forced draft purposes. Therestrio tion or resistance to flow of the fluid to the fan or blower, as well as from it, is often continuously changing. For example, in ventilating systems, windows or doors are being opened and closed, which changes the restriction on the inlet side, if the air is being exhausted from the building, and on the discharge side if fresh air is being blown into the building. Similarly, in mechanical draft systems, the resistance to flow through the combustible is constantly varying, due to such causes as changes in the quantity and quality of the combustible used, and the formation of ash and clinker. If it is an induced draft system, this changes the flow of I gas to the inlet of the fan, and if a forced draft system, it alters the flow of air from the discharge of the blower.

It is often desirable that the weight quantity of air or other gas discharged be maintained constant, or approximately constant, irrespective of changes in the resistance or restriction. Fans or blowers have a characteristic which automatically partially compensates for these changes, this characteristic being that the head set up by the fan or blower, when running at constant speed, increases as the output decreases, and vice versa. This characteristic is present to a different degree in different types of fans and blowers, and the extent to which it is present in any given type varies with conditions of operation. The changes in restriction cause changes in the density of the gas flowing to or from the fan or blower, as the case may be. The density of the entering gas may also change, due to other causes, such as changes in temperature and this in turn affects the density of the discharged gas. It is evident, therefore, that if the weight discharged is to be kept constant, account must be taken of changes in density, as well as in the velocity of discharge.

The weight of gas discharged per minute will vary directly as the velocity and as the density or weight of the discharged gas. The product of the weight times the velocity is the momentum, and a change-in either the density or the velocity causes a corresponding change in the momentum. Therefore, a device which is sensitive to changes in the momentum of the discharged air or gas, will be sensitive to changes in the weight quantity discharged.

In my invention there is employed a fan or blower which is driven by a suitable variable speed motive power agent. This agent may beany one ef various types, ac-

cording to what is best suited to the conditions existing, such as for example a steam engine, an internal combustion engine, a steam turbine, or an electric motor. This motive power agent may drive the fan or blower by belt or gears, or it may be direct connected. In illustrating my invention, 1 have shown a steam engine direct connected to a fan or blower.

In carrying out my invention, I locate at a point where it will be susceptible to changes in the momentum of the gas discharged by the fan or blower, a device which is affected by changes in the above mentioned momentum. The device is movable in response to changes in this momentum, and may be installed at a suitable point, such as in the fan or blower discharge, or preferably in a passageway or pipe through which the fluid discharged by the fan or blower travels. It may be desirable, according to the conditions existing in any particular case, to locate the device in an enlargement, or a restriction, or in an elbow of said passageway or pipe. It is not necessary to confine the location of this device at any one point. The device may be made in any one of a variety of forms. It may consist of one or more movable vanes or surfaces, or groups of them, each vane or surface being placed so as to alter the directions of the lines of flow of the fluid. The vane or vanes may be flat or curved, or both. The vane or vanes being at an angle to the line of flow, as the fluid meets and passes them its direction of flow is changed, causing a reactive force on the vane or vanes due to the momentum of the fluid. A connection is provided between the device susceptible to changes in momentum of the fluiddischarged, and the controller, so that action of the device is transmitted to the controller. This connection may be accomplished in various ways, according to what the conditions demand as regards the power of the device and the power required to actuate the controller, also the distance between the location of the device and the controller, and the type of controller used. It may, for example, be desirable to have hydraulic connection with a pilot valve or re lay system, or possibly an electrical connec- 5 tion'. The connection, in conjunction with the reactive member illustrated, is a direct connection by means of rods and levers.

The following is a description of an embodiment of my invention, reference being had to the accompanying drawings, in which Figure 1 shows a side elevation of my improved fan or blower system, with part of the discharge pipe broken away, and Fig. 2 shows a left hand end elevation of the same.

Referring more particularly to the drawings, 1 is a fan or blower preferably of the centrifugal type, having a central inlet 2 and a discharge outlet 3.

at is a steam engine directly connected to the blower by the common shaft 5. This steam engine is provided with the ordinary steam chest 6 containing the engine valves operated by the eccentric 7,

8 is an ordinary governor for preventing the engine from racing, controlling the gov ernor valve 9 and driven by the belt 10 from the engine shaft.

11 is the steam supply pipe leading from the boiler. In the pipe 11 is a supplemental controlling or throttle valve 12, which is actuated by a rod 13. This rod is provided with a spring 14, which normally tends to hold the valve open. Connected to the valve rod 13 by a link 15 is a lever 16, pivot-ed at 17. This lever at the point 18 is connected by a link 19 to a crank arm 20, mounted on the shaft 21, carried by suitable bearings 22-23 in the discharge pipe of the blower. Upon this shaft 21 is mounted a reactive or vane member 24, having one or more blades 25, in the present instance six blades being shown symmetrically arranged about the shaft 21, which is set parallel to the axis of the discharge passageway, and against which member the air passing through the discharge impinges. These blades are so shaped that when the air passing through the discharge passageway strikes them, it tends to move the crank 20 upward so as to move the valve rod 13 downward to close the valve 12, the movement being due to the momentum of the air. The outer end of the which works a plunger 27 for preventing sudden movement of the lever 16 and the parts connected thereto. The outer edge of each of the blades inclines or curves forward, the inner edge preferably being parallel to the shaft 21. The discharge passagewayin which the reactive member constituted by the blades 25 is mounted is preferably of cylindrical form, the shaft 21 coinciding with the axis of the cylinder. Vith the construction shown, the shaft 21, together with the vanes 25 which it carries, may turn through an are about the axis, a 1 resistance to the turning of these parts being provided in a suitable manner, in the present instance by the spring 1%.

Q In the operation of the apparatus, as the fluid passes through the discharge and strikes against the blades 25, the lines of flow are changed and a torque is created by the reactive force of the fluid on the vanes, due to its momentum. This torque acts against the resistance 14. This resistance may be provided in the form of a weight instead of the spring, or in conjunction with the spring. The adjustment of the spring or weight, or both, may be graduated so as to indicate the weight quantity of air or gas discharged. The intensity of this reactive force or torque is dependent on the momentum of the fluid passing through the discharge and the extent to which the reactive member turns on its axis is therefore dependent on the extent of the change in the momentum of the passing fluid. The type of controller used will depend upon the form of motive agent used and the special conditions existing in any particular case. In the embodiment shown in the drawings, 3 a steam engine being used, I have shown 1 means whereby the reactive member acts to lever 16 is provided with a dash-pot 26, in

vary the steam supply. After the blower has been started and the discharge has attained its normal or desired condition, the reactive member will act to either increase or decrease the speed of the motive power agent, so as to maintain the quantity of fluid discharged by weight substantially constant under varying conditions. When the blower is discharging the proper weight quantity of gas, the reactive member is held in a state of equilibrium by the action due to the momentum of the gas tending to turn against the force of the spring 14. If now the density of the gas coming to the blower increases or decreases, it will cause an increase or decrease in the density of the gas discharged, which in turn increases or decreases the momentum of the discharged gas. An increase of the momentimi will cause the reactive blade member to turn, against the force of the spring, and the connection transmits this motion to the throttle valve 12, closing it slightly, thereby cutting ofl the steam supply which slows down the speed of the engine until the velocity of the gas discharged has decreased sufficiently to bring the momentum, and therefore the weight quantity discharged, down to the original amount. Similarly, a decrease in momentum will allow the spring 14 to turn the blade member in the other direction, opening the throttle valve 12 and speeding the blower up until the original weight quantity is again discharged. If the velocity of flow t0 the blower is decreased, the velocity of discharge and therefore the momentum of discharge, will be decreased, and vice versa. Similarly, if the velocity or density of the gas being discharged is changed, as by a change in the restriction against which the blower is working, the momentum of the gas passing through the blade member changes. The apparatus, it will therefore be seen, acts to keep the weight quantity discharged substantially constant, irrespective of changes in the velocity or density of the gas flowing to the blower, or in the velocity or density of the gas flowing from the blower, and irrespective of whether these various changes come singly or together.

When the inlet or suction is to be connected a fan or blower with a single inlet is usually used; otherwise, the fan or blower is often of the double inlet type. The illustration shows a single inlet fan or blower.

As will be evident to those skilled in the art, my invention permits of various modifications without departing from the spirit thereof or the scope of the appended claims.

What I claim is:

1. In an apparatus of the character described, the combination of a blower having inlet and outlet openings, a reactive member acted upon by the discharge of said blower and responsive to changes in 1110 mentum of the fluid discharged, a prime mover for operating said blower, and means for controlling said prime mover actuated by said reactive member so as to increase the speed of the prime mover as the momentum of the discharge decreases, and vice versa, the movement of said reactive member being limited by said controlling means.

2. In an apparatus of the character described, the combination of a blower having inlet and outlet openings, a reactive mem ber acted upon by the discharge of said blower and responsive to changes in momentum of the fluid discharged, a prime mover for operating said blower, and means for controlling said prime mover actuated by said reactive member so as to increase the speed of the prime mover as the mo mentum of the discharge decreases, and vice versa, said reactive member comprising a movable blade mounted in a passage through which the discharge from said blower passes, the movement of said blade being limited by said controlling means.

3. In an apparatus of the character de scribed, the combination of a blower having inlet and outlet openings, a reactive member acted upon by the discharge of said blower and responsive to changes in momentum of the fluid discharged, a prime mover for operating said blower, and means for controlling said prime mover actuated by said reactive member so as to increase the speed of the prime mover as the momentum of the discharge decreases, and vice versa, said reactive member comprising a plurality of blades mounted in a passage through which the discharge from said blower passes, the movement of said blades being limited by said controlling means.

4. In an apparatus of the character described, the combination of a blower having inlet and outlet openings, a reactive member acted upon by the discharge of said blower and responsive to changes in momentum of the fluid discharged, a prime mover for operating said blower, and means for controlling said prime mover actuated by said reactive member so as to increase the speed of the prime mover as the momentum of the discharge decreases, and vice versa, said reactive member comprising a plurality of blades mounted in a passage through which the discharge from said blower passes, and

movable about an axis parallel to the axis of said passage, the movement of said blades being limited by said controlling means.

5. In an apparatus of the character described, the combination of a blower having inlet and outlet openings, a reactive member acted upon by the discharge of said blower and responsive to changes in momentum of the fluid discharged, a prime mover for operating said blower, means for controlling said prime mover actuated by said reactive member so as to increase the speed of the prime mover as the momentum of the discharge decreases, and vice versa, said reactive member comprising a movable blade mounted in a passage through which discharge from said blower passes, the movement of said blade about an axis parallel to the axis of said passage being limited by said controlling means, and a dashpot connected to said reactive member so as to dampen its movements.

6. In an apparatus of the character described, the combination of a blower having inlet and outlet openings, a reactive member acted upon by the discharge of said blower and responsive to changes in momentum of the fluid discharged, a prime mover for operating said blower, a controller for the supply to said prime mover connected to said reactive member and actuated thereby to cut down such supply, and means normally tending to increase said supply, the movement or said reactive member being limited by said controller.

NORMAN L. SNOW.

Witnesses: v

H. B. BROWNELL, E. E. Monsn.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G.

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