US2692504A - Emergency damper control - Google Patents

Description

Oct 1954 B. E. COLBURN ET AL EMERGENCY DAMPER CONTROL Filed June 2, 1949 50 5 9M3. M U a 2 m 0 a v J 5 Snnentors 55mm. 5. Ca; as

4. Co "a wew/ (Ittorneg s Patented Oct. 26, 1954 UNHTED STATES PATENT OFFICE Bear! E. Colburn and Lee Colburn, Green Bay, Wis.

Application June 2, 1949, Serial No. 96,795

12 Claims. 1

Our invention relates to improvements in emergency damper controls.

Heating devices, such as furnaces and other fuel burning units relying upon air supply and the adjustment of quantity of air supply for their control, even though provided with automatic devices for the adjustment of dampers, check drafts, and draft doors, ofier a distinct fire hazard in the event that the operator forgets to retard the fire, or in the event that the automatic device fails, for lack of power, or fails due to mechanical disability. It is the object of our invention to provide an emergency control, supplemental to either a hand-operated or automatically-operated air feed control for furnaces or heaters, whereby, in the event of an overrun of temperature, to shut off air feed or otherwise to check combustion.

More specifically stated, it is the object of our invention to provide a thermostatically responsive device which will assure return of damper, draft doors, or checks to fire retarding position if temperature exceeds a safe control value.

Another object of our invention is to provide a thermostatically releasable emergency link for a conventional control of a furnace draft.

In the drawings:

Fig. 1 is a perspective of our emergency draft damper control, showing our emergency releasable strip chain in normal, or standby position, in readiness for an emergency release.

Fig. 2 is a side elevation of a conventional Warm air furnace with our control in position for draft door release.

Fig. 3 shows our invention installed on a conventional warm air furnace in position for check damper release.

Fig. 4. is a longitudinal vertical section through our emergency control.

Fig. 5 is a section on line 55 of Fig. 4.

Fig. 6 is a section on line 6-6 of Fig. 5.

Fig. 7 is a detail of our emergency trip chain and illustrating its mode of releasable attachment to the. operating arm of our control.

Like parts are designated by the same reference character throughout the several views.

Conventionally, draft doors ill for furnaces H, and check dampers i2 for such furnaces are controlled by control chains !3 in a well-known manner, either by connection to manually operated devices, or to automatically controlled devices which raise and lower the chains to alter the position of a draft or check.

Draft door It) or check damper l2 will either close of its own weight, as shown in Fig. 2, or a special weight, as shown at M may be used to assure that the damper will assume a safe position if the chain i3 is released. If, however, due to power failure of an automatic damper control device or to forgetfulness of the operator of a manually controlled furnace, the damper or check is left in position for rapid combustion of fuel in the furnace, a dangerous condition may develop. We, therefore, provide our emergency draft damper control now to be described.

Our draft damper control includes an instrument housing l5 on a back plate 16 which may be secured by suitable sheet metal screws or otherwise to the casing of a furnace l I as shown clearly in Figures 2 and 3. Extending forwardly from a side wall of the instrument housing [5, is a free floating lever ll which may oscillate freely about the shank I 8 of a slotted thimble l9 mounted in a boss 20 forming a part of the side wall of the housing I5. Control chain [3 is connected near the outer end of lever I! and we provide a control chain from the lever l! to the damper ID or check l2.

At 26 the arm I! is provided with a spool apertured at 21 to freely receive a special, bead type trip chain 28. This forms an emergency link between the chain 25 and a release ring receivable in slotted thimble [9. So long as the release ring is held in the slot in the thimble l9, chain l3 and the chain 25 act as one continuous pull chain element so that the automatic or manual device used to adjust these chains and the position of the dampers to which they are connected will be substantially in accord with conventional practice. Dampers and draft doors are often quite heavy, and it is for this reason that we provide pin 29 projecting from arm I! at a point spaced from the spool and somewhat below a straight line drawn between the trip rod and the spool. Release of the ring 30 under emergency conditions and the use of pin 29 will be described below.

When the ring is released, the weighted damper pulling downwardly upon chain 25 will pull the free running trip chain 28 through spool 26 until the ring 36 strikes the spool. This will in effect add some chain to the effective length of the chain 25 and permit the damper or check to close.

Extending rearwardly from the back plate [6 into the bonnet of furnace H is a thermostatic device including a mounting tube 3|, a helically wound oi-metallic element 32 and a thermostatically controlled rod 33 which extends centrally of the tube 3| into the instrument housing l where the end of the thermostatically controlled rod 3| is provided with a trip flange 34. Tube 3i is guided in collar 35 welded or otherwise secured to the back plate it, and the tube may be oscillated in the collar by means of a temperature setting lever 36, which is rigidly secured to a tube collar 3'! fixed upon inner end of the tube 3! as shown clearly in Figures 1, 4 and 5. Temperature setting lever 58 extends through the top of the instrument housing l5 and is disposed in front of calibrations marked on the back plate and will therefore indicate the temperature setting of thermostat 32, since one end of the bi-metal helix is secured to the tube at 38 and the other end of the helix is secured at 39 to rod 33.

It will be clear from this description that upon movement of the temperature setting lever 36 the tube 3| is oscillated so as to change the position of the point of attachment of the helix 32 at 38. This point of attachment is the reference point from which the helix operates and therefore determines the temperature at which our emergency control is to operate.

In Figure 6 it will be noted that slot 4!} extends substantially beyond the axis of shank l8 of the thimble and that the shank it is bored at 4| to loosely receive trip rod 42, which extends retractably transversely of the slot 40 and transversely of the interior of the instrument case. The trip rod is provided with a shoulder flange 43 and a knurled extension 44 to protrude from the instrument case on the side opposit thimble i9. Reset spring 45 between the side of the instrument case and the shoulder flange 43 of trip rod 42 constantly urges the trip rod toward the left as seen in Figures 5 and 6.

Extending from collar 34 on rod 33 is a trip lever 46, which is in position to oscillate against shoulder flange 43 of trip rod 42 in opposition to the thrust of spring 45 when the temperature of thermostatic element 32 increases so as to provide increased torque.

When trip lever 46 does not interfere, spring 45 thrusts rod 42 into position across the slot 44 so that it may extend through release ring 30 and retain it in position during normal operation of the furnace.

It will now be clear that so long as the trip rod 42 is in position to retain the release ring 30 the furnace controls applied to chain lever l? and chain will operate in the conventional manner to raise and lower chain 13 to open and close any drafts or dampers connected thereto. Throughout such normal operation the arm ll will oscillate freely without aifecting any of the mechanism in the instrument housing [-5, and release ring will oscillate freely about the trip rod 42.

If, however, the temperature of the thermostatic element 32 which extends into the bonnet of the furnace II, exceeds the temperature for which arm 36 has been set, the trip lever 45 oscillated by the thermostatic action upon helix 32 and rod 33 will bear against shoulder 43 to compress spring 45 and retract trip rod 42 from slot 40. When this occurs, release ring 35} is released by trip rod 42 and the freely running bead chain 28 will slip through spool 26 so as to add a number of inches to the efiective length of chains 25 and is, thus permitting the damper or check to close of its own weight.

To set our emergency draft damper control the release ring and the chain 28 may be manually pulled back into the position shown in Figures 1,

5, and I, while the knurled reset extension 44 is pulled outwardly of the house 15, against the compression of spring 45. Then while the release ring is held in position, the trip rod 42 will be permitted to assume the position in Figure 5 under the thrust of spring 45. Obviously this cannot be done while the trip lever 46 is in a position dictated by a high temperature in the furnace bonnet, but will ordinarily be done after the fire in the furnace has been damped by our emergency release of the chain 28.

It will be noted that we have made provision for adjustment of the critical release point of our control, since arm 38 and tube 3| to which it is attached constitute the reference point from which the helix 32 operates. If there is need to recalibrate the thermostatic device, we provide a screw at 47 through collar 3? to bear against the tube 3!. This set screw may be released and a different setting of the collar 37 and arm 36 with reference to the tube may b determined. Then when the set screw 41 is again tightened a new reference point for the thermostat 32 will have been obtained and the temperature setting at which the trip arm 46 will effectively withdraw the trip rod 42 can be accurately set by moving the temperature setting lever 36.

Obviously chain arrangements between our emergency draft damper control and the actual draft door l0 may be direct as shown in Figure 2, or it may follow devious paths over pulleys 47, 48, to check l2 as shown in Figure 3.

We referred above to the fact that a heavy draft door might cause trouble in the operation of the release ring 30. Since friction induced be tween rod 42 and the ring may be considerable, pin 29 is so positioned that trip chain 28 may be drawn beneath it and the pin will then be disposed between two of the beak like links. The person resetting our emergency damper control can pull the trip chain far enough toward the trip rod 42 so that some slack may be provided in the length of trip chain extending from pin 29 to the release ring 30. In fact, then, the trip chain is snubbed around the pin 29 and will remain in this position to take some of the strain off of the slack and of the trip chain, thus reducing the friction between trip rod 42 and the ring 30 when an emergency release trip operation is to be accomplished.

In the operation the release ring is held firmly in the slot 40 by the trip rod 42, until the temperature of the bimetallic helix 32 is raised to the critical degree to which the temperature setting lever 36 has been set. As the temperature increases the trip lever 46 is oscillated to the right (counterclockwise) as seen in Fig. 5, and the trip rod 42 is thrust to the right against the pressure of spring 45. Finally the ring 30 is released by the trip rod so that the trip chain 28 slides through spool 26. Thus, when the ring 30 strikes the spool the length of the trip chain 28 has been added to the controlled chain 25 and this is sufiicient to permit the damper Ill or check l2 to close.

When the fire has been damped sufficiently to cool the thermal responsive helix 32 our emergency damper control may be manually reset. The trip lever will have moved clockwise to a position permitting the spring to thrust trip rod 42 to the left (Fig. 5), and the trip rod can be with drawn to the right, manually, while ring 30 is inserted in the slot 40. Trip rod 42 may then be manually released, to be "laced through the ring. Our emergency damper control is then set for an automatic release, should an emergency hi temperature condition again be reached.

From the above description it will be seen that our emergency draft damper control provides an effective release of an emergency trip chain 28 in chains l325 to shut down furnace operation in the event that excessive temperatures develop in a furnace. Many of the automatic furnace controls now on the market are equipped with thermostatic devices known as limit controls by means of which it may be predetermined that the automatic temperature control of the furnace will shut down the furnace drafts or other combustion promoting means at a predetermined high temperature. Such predetermined high temperature might be 300 degrees in the bonnet of the furnace l l, and our emergency draft control thermostat 32 would then be set at a somewhat higher temperature, as for instance, 325 degrees. If the furnace temperature then exceeded the normal 300 degree limit, this indicating that the ordinary automatic control had failed, the trip lever 46 would, at 325 degrees, withdraw the trip rod 42 and release ring 30 for an emergency shut down of the dampers.

We claim:

1. In a device of the character described a swingable member having a fixed pivotal mounting and a floating end, a pair of control linkage members extending respectively to and from the floating end of said member whereby to additively provide control linkage of a normal control length, emergency linkage disposed in releasably retained position parallel to the swingable member and connected to one of said pair of control linkage members whereby upon release of the emergency linkage its length is added to said normal control length.

2. The device of claim 1 wherein the swingable member is provided with an apertured spool at its floating end through which the emergency linkage is freely movable and one end of the emergency linkage is provided with a release ring too large to pass through the spool.

3. An emergency damper control having a housing providing bearings for a pair of rods'disposed at right angles to each other; one of the rods having a thermally responsive member for oscillation of the rod and the other rod being a shouldered trip rod reciprocable in its bearings; a bearing for one end of the trip rod comprising a shanked and slotted thimble; an arm freely rotatable on the shank of the thimble and provided with a control chain to move the arm; a spool on the arm spaced from the thimble; a controlled chain disposed over the spool and provided with a release ring disposable in the slot in the thimble whereby to be releasably retained by the trip rod; and a trip arm connected to the thermally responsive rod in position to bear upon the trip rod and withdraw it from the release I'll'lg'.

4. An emergency damper control having a housing providing bearings for a pair of rods disposed at right angles to each other; one of the rods having a thermally responsive member for oscillation of the rod and the other rod being a shouldered trip rod reciprocable in its bearings; a bearing for one end of the trip rod comprising a shanked and slotted thimble; an arm freely rotatable on the shank of the thimble and provided with a control chain to move the arm; a spool on the arm spaced from the thimble; a controlled chain disposed over the spool and provided with a release ring disposable in the slot in the thimble whereby to be releasably retained by the trip' rod; a trip arm connected to the thermally responsive rod in position to bear upon the trip rod and withdraw it from the release ring; and a spring between the housing and the shoulder on the trip rod to urge said rod to ring retaining position.

5. A damper control connection extending from a damper to a point of control, a movable member at the point of control provided with releasable attaching means attached to the damper control connection, a spool on the movable member spaced from the releasable attaching means over which spool the damper control connection may move when released and a snubbing pin fixed to said movable member and about which the said control connection is snubbed between the spool and the releasable attaching means.

6. A damper control connection extending from a damper to a point of control, a movable member at the point of control, said movable mem ber being provided with a fixed pivotal mounting, releasable attaching means adjacent said pivot and to which the damper control connection is releasably attached, a spool on the movable member spaced from the releasable attaching means and over which spool the damper control connection may move when released and a snubbing pin for said control connection between the spool and the releasable attaching means and thermostatic means having a trip for releasing the releasable attaching means.

'7. In a device of a character described, a supporting housing provided with a slotted thimble having a bored shank, a trip rod reciprocable in the bore in said shank and extending across the slot, a thermostatically responsive member positioned to bear against the trip rod, and a damper control trip chain having a release ring receivable in the slot for engagement by the trip rod, a free floating lever mounted upon the shank of the thimble, and a spool on the lever mounted at a point spaced from the trip rod for passage of the trip chain and retention of the ring.

8. A swingable emergency control arm for a two-part tension connection for a damper, said arm being swingable about a fixed center, one of said parts of the tension connection being directly connected to a swingable outlying portion of said arm, the other of said parts being releasably connected adjacent the center and held approximately parallel to the arm by a pulley-like spool adjacent said outlying portion of the arm, and a thermally responsive tripping device adjacent said center to release said other part of the twopart connection whereby to lengthen the tension connection.

9. The control of claim 8 wherein the spool is shaped to retain the released end of said other part.

10. An emergency damper control comprising a support, thermall responsive trigger mechanism mounted on said support, an arm pivotally connected to said support, portions of the arm remote from the pivot being provided with connections for control linkages to a damper and connections for control linkages to a damper control, said control linkages being in series and said arm being normally oscillatable about its pivot Without materially altering the combined lengths of the said control linkages, one of said control linkage connections comprising an apertured spool on the arm, and a releasable coupling connected with said trigger mechanism and to which coupling one of said control linkages is attached;v said one control linkage extending to said coupling through said spool aperture and along said arm, the thermal response of said trigger mechanism being effective to release the coupling and said one control linkage for movement along the arm whereby to increase the effective combined length of said linkages.

11. The device of claim 10 wherein said one linkage has a stop portion engageable with said spool whereby to limit the increase of the com- 10 bined lengths of said control linkages upon actuation of the trigger mechanism.

12. The device of claim 11 wherein said thermally responsive trigger mechanism comprises members mounted for relative movement and thermally responsive means for causing such relative movement, one of said members having 87 motion transmitting connection with said releasable couplingand the other of said members being provided with means for adjusting said mechanismto be responsive to a selected temperature.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 552,924 Reynolds Jan. 14, 1896 1,966,724 Kimball July 17, 1934 2,190,892 Swepston Feb. 20, 1940 2,240,763 Dillman May 6, 1941 2,249,886 Dayton July 22, 1941 2,284,082 Bloch May 26, 1942 2,302,108 De Lancey Nov. 17, 1942

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