US2211501A - Furnace regulating system - Google Patents

Description

Allg- 13, 1940- c. l. GooDHART FURNACE REGULATING SYSTEM 2 sheets-'sheet 2 Filed July 17, 1937 Www.

Patented Aug. 13, 1940 UNITED STATES PATENT oFFicE 3 Claims.

This invention relates to a furnace regulating system and more particularly to a system in which the draft through the furnace is automatically controlled. Y y

An object of the invention is to provide means which will automatically compensate for the variations in the draft of the ilue passage and which will also serve to check the furnace draft quickly when the furnace becomes sufliciently hot.

Another object is to provide a regulating system in which a blower is used to force the draft through the furnace and in which a iiue draft door is automatically operated when the blower ceases to operate. A further object is to provide pressure-sensitive means and temperature-sensitive means for controlling the operation of the blower and flue draft door.

An embodiment of the invention is illustrated in the accompanying drawings in which- Fig l is a view in side elevation, part of the flue passage being shown in section; Fig. 2, a front elevational view of the blower means; Fig. 3, a detail sectional view of the blower means, the view being taken as illustrated at line 3 of Fig. l; Fig. 4, a detail sectional view taken as indicated at line 4 of Fig. 1, and showing the iiue door control mechanism; and Fig. 5, a schematic view showing the 'electrical connections employed.

As illustrated, A designates a furnace; B, blower means for forcing the furnace draft; C, a flue passage containing a draft door; and D, automatically controlled mechanism controlling the position of the flue draft door.

The furnace A may be of any type such as warm air, steam, hot water, or other familiar type. The embodiment illustrated is of the steam type and has a steam pressure control I which is effective for lshutting oi the furnace draft when the steam pressure in the boiler reaches a predetermined amount.

'I'he flue passage C for carrying away smoke and fumes comprises the casing II which serves as a common smoke pipe and has its end received within opening I2 of chimney I3. Casing I'I is here shown as square in cross -section, but itv may be of any suitable shape. A cylindrical extension IIa provides the side opening I4 through which air from the furnace room may enter the flue passage. In this opening a door I5 of circular shape to t opening I4 is pivotally supported on a pin I6 engaging the sides of extension I Ia. As clearly shown in Fig. 4, pin I6 is above the vertical center of the door so that when there is a strong draft within the flue passage the door will be pulled to open position. For adjusting the door to be pulled open to a lesser or greater extent, I provide a weight I1 adjustably carried on bracket I8. When the weight I8 is moved farther from the pivot I6 a stronger flue draft is (ci. e36-.9)

required to open door I5. Opening I4 and door I5 may be circular or square or any other shape that may be desired.

It is well'known that the strength of the ue or chimney draft will vary from time to time, due to changes of atmospheric conditions and changes in the direction and velocity of winds, etc. When changes take place to make the flue draft stronger, door I5 will be opened farther so that more air from the furnace room will be admitted into the flue passage, and this will relieve the effective draft through the furnace. In this way the automatic opening and closing of door I5 serves to maintain a practically constant draft through the furnace.

The operation of door I5 is also controlled by mechanism D which includes an arm 20 pivotally mounted at one end to a bracket 2| secured to casing extension I Ia. The other end of arm 20 is equipped with a Weight 22 and is attached by means of chain 23 to the end of finger 24 secured to door I5. A solenoid 25 is mounted to bracket 2l above arm 20 and is adapted when energized to bring this arm to its raised position as shown in Fig. 4, and maintain it in this position. A

bar 26 extending within the solenoid may be pivotally connected at its lower end to the central portion of the arm. When the solenoid is energized, bar 26 is drawn inwardly within the solenoid to raise the arm 20. Weight 22 may be moved toward or away from the end of arm 20 to adjust the amount ofy force exerted by this arm. l A stop for limiting the opening movement of door I5 is provided bythe bolt 2lia which is pivotally attached at its one end to arm 20 and has its other end in slidable engagement with the bracket of solenoid 25. A nut 20h on the upper end of bolt 20B limits the downward movement of the bolt and so limits the downward travel of the arm.

The blower means B includes a casing 30 containing a fan 3| which is driven by suitable power means such as the electric motor 32. Casing 30 has a side extension 33 which provides the intake opening 34. A door 35 is pivotally supported in this opening at points above its vertical center so that when the fan is in operation the air from the outside will press this door open, but when the fan is not in operation this door will effectively close the intake opening. If desired, a solenoid (not shown) may be mounted adjacent door 35 and arranged to open this door almost instantaneously when the electric motor is in operation and permit the'door to close instantaneously when the motor is deenergized.

The pressure-sensitive and temperature-sensitive control means are more clearly illustrated in Fig. 5 of the drawings. The steam control I0 is of the diaphragm type having a pivoted arm 4I which is actuated by the diaphragm and which is provided with an adjustable weight 42. When in lower position, the end of arm 4I makes electrical contact with spring 43. When the steam pressure becomes greater, arm 4I moves upwardly to break this electrical contact. If desired, a mercury tube type switch may be substituted for the contact arrangement provided by spring 43. In such case the mercury switch would be so arranged that the raising of arm 4I would operate to tilt the mercury tube to break the electrical contact. The temperature-sensitive control may be any common make of thermostat in which electrical contact is broken when room temperature attains a predetermined degree.

The leads 5I and 52 may be connected to any suitable source of electrical energy, and each of the controls may be connected as illustrated in Fig. 5. It will be seen that motor 32 and solenoid 25 are connected in parallel and that each is in series with the thermostat 50 and steam control I 0.

The operation of my improved draft regulating system may be briefly stated as follows:

When the temperature of the rooms being heated and the pressure of the steam in the boiler is below the predetermined amounts for which the devices 50 and I0 are set, an electrical current will flow from lead 5I, through both of these devices and will energize both solenoid 25 and motor 32. Operation of motor 32 actuates fan 3| of the blower and causes door 35 to open and air to be forced through the furnace, which makes the furnace re burn briskly. When the room being heated attains the temperature at which the thermostat 50 is set, this device will operate to break the circuit through both motor and solenoid. The blower then ceases to operate and door 35 closes to shut oi the entrance of any appreciable amount of air through the draft inlet to the furnace. However, sufficient amounts of air must be allowed to enter the furnace to take care of combustion and prevent an explosion due to unburned gases.

During operation of the blower and when the circuit is completed the arm 20 is held in raised position by the energized solenoid 25; but when this circuit is broken and solenoid 25 is deenergized, this arm is moved downwardly by weight 22. Downward movement of arm 2U pulls chain 23 downwardly and causes door I5 to move quickly into wide open position. So long as this solenoid is deenergized the door will be maintained in this position.

The opening of door I5 through the action of the solenoid serves to admit a great amount of air into the flue passage so as to cut down the effective draft on the furnace to a minimum. The advantage of this action is to prevent the hot gases from being drawn up the flue passage with the strong draft, and causes these gases to be held in the furnace to give olf their heat to the water or air being heated. Thus door I5 is operated through two actuating means. During operation of the blower means this door is acted upon by the changes in the strength of the flue draft and when the blower means is not in operation the door is acted upon by the weighted arm 20. It may be noted that the operation of door I5 through the action of the solenoid is quick and positive while its normal operation in overcoming the variation in flue draft is usually slow and within narrow limits of movement.

Also when the steam pressure reaches the setting of control II), the circuit will be broken and both motor and solenoid deenergized with the results as above explained.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom but the appended claims should be construed as broadly as permissible, in View of the prior art.

I claim:

1. In a steam furnace, a blower for forcing air into the draft inlet of said furnace, an electric motor for driving said blower, a flue passage for conducting smoke away from said furnace, an opening in the side of said flue passage, a door normally closing said opening and effective to move toward open position when the draft in said passage becomes greater than a predetermined amount, mechanism for moving said door to open position, said mechanism being independent of the draft in said passage, a restraining means for preventing the operation of said mechanism to open said door and means rendering said restraining means effective only when the steam pressure of said furnace is below a predetermined amount and the temperature of the space being heated by said furnace is below a predetermined degree.

2. In a steam furnace, a draft inlet for introducing air into said furnace, a flue passage for conducting smoke away from said furnace, an opening in said flue passage, a door normally closing said opening, said door being movable toward open position when the draft in said passage exceeds a predetermined amount, mechanism for moving said door to open position, said mechanism being, independent of the draft in said passage, restraining means for preventing the operation of said mechanism to open said door, and means rendering said restraining means ineffective when the steam pressure of said furnace exceeds a predetermined amount or when the temperature of the space being heated by said furnace exceeds a predetermined degree.

3. In a furnace, a blower for forcing air into the draft inlet of said furnace, a flue passage for conducting fumes and smoke away from said furnace, a casing mounted on said iiue passage and communicating therewith, an opening in said casing, a door pivotally supported in said casing normally closing said opening, said door being normally adapted to move about its pivot toward open position when the draft in said iiue passage becomes greater than a predetermined amount, and being, in all positions, outside said flue passage, the amount of movement of said door being dependent upon the strength of the draft in said passage, a weight connected to said door and adapted to move the same to full open position and to maintain said door in such position, solenoid means for restraining the action of said Weight when said blower is in operationl thereby permitting said door to move freely from closed position to any open position when acted upon by the draft in the flue passage, and single means for actuating said blower and said solenoid means, said single means being adapted to be rendered inoperative by a temperature sensitive control.

' CHARLES I. GOODHART.

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