Blast Coil Heater

Abstract

A blast coil heater unit includes an open rectangular frame having unitary transverse ceramic partitions disposed at spaced intervals along its length. The ceramic partitions are apertured to provide lengthwise support for longitudinal portions of an electric heating coil extending therethrough. The ceramic partitions are attached to the frame by means of inwardly extending retaining tabs and are cushioned against shock by spring elements disposed at the upper and lower ends between said partitions and said frame. Transverse tie members are provided to stiffen the frame along its length.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to an electric coil heater unit and particularly to a blast coil heater unit installed in an air duct.

Heater units of the type under consideration have been known for many years. Such units include essentially an open frame having means within the open area to provide support at spaced intervals for the structurally weak electric coil elements. In the past the metal partitions, welded or otherwise fixedly attached to the open frame, have been used to support the coil. Although such partitions are not difficult to attach to a metal frame, metal is obviously an unsuitable material for supporting the heated electric coil elements. In consequence of this, it has been necessary to provide the metal with ceramic attachments to support the coils. Beadlike ceramic inserts are commonly used for this purpose such inserts being attached directly to the metal partition. A common method of achieving this has been to provide relatively complicated double-walled partitions having dished formations sandwiching the inserts.

The present device overcomes this and other disadvantages inherent in prior art devices.

SUMMARY OF THE INVENTION

This blast coil heater unit provides a metal frame having a plurality of apertured ceramic partitions disposed at spaced intervals along the length to support the electric heating coil elements.

The attaching of the rigid ceramic partitions to the exterior metal frame is achieved by providing a shock resistant connection between the partitions and the frame to cushion the partitions and preclude breakage thereof.

The frame can be transversely stiffened with a minimum reduction of the cross sectional area of the air duct by providing reinforcing elements adjacent the sides of the partitions.

This blast coil heater unit is relatively simple and inexpensive to manufacture and provides a substantially projection free exterior, which facilitates installation.

It is an important object of this invention to provide a blast coil heater unit which includes a substantially rectangular frame supporting a plurality of elongate coil portions disposed in parallel relation with the sides of the frame and a plurality of transversely disposed ceramic support partitions for the coil portions disposed in spaced relation along the length of the frame and attached to the frame without the need for fasteners.

It is another object to provide the rigid ceramic partitions with a plurality of apertures for receiving and supporting associated coil portions, and to provide means attaching the ceramic partition ends to the frame including resilient means to cushion said partitions against shock.

A further object lies in the provision of attachment means which include a plurality of inwardly extending tab elements, formed from the frame material and spaced on either side of each ceramic partition, to operatively overlap and retain said partitions, the tab elements providing a pocket accommodating an associated leaf spring at each end of each partition to provide the cushioning of said partitions from said frame.

An important object is to provide ceramic partitions which are shorter than the distance between the frame sides and longer than the clear distance between the tab elements to facilitate insertion of said partitions within the tab defined pockets, said spring elements having an unsprung dimension sufficient to insure that spring pressure is exerted against the ends of said partitions in the installed position.

Another important object is the provision of spaced reinforcing tierods to insure that the rectangular frame maintains its shape without the need for stiffening flanges.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of the heater unit;

FIG. 2 is an end view of said unit with the end member partially cut away to show details of the ceramic partition and attachment means;

FIG. 3 is a fragmentary sectional view taken on line 3--3 of FIG. 2; and

FIG. 4 is a perspective view illustrating a typical heater unit installation in a duct.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now by characters of reference to the drawing and first to FIG. 1 it will be understood that the blast coil heater unit, generally indicated by numeral 10, comprises essentially an open rectangular frame 11 having lengths of heating coil disposed therein so that air passing through said frame is heated. As shown in FIG. 4 the heater unit is provided with a terminal box 12 and is installed within an air duct 13 by slipping the frame 11 inside the duct through a rectangular opening 14 in the side of said duct. The terminal box 12 may be attached to the duct 13 to hold the heater unit 10 securely in place within said duct.

Turning now more specifically to the construction of the heater unit 10 shown in FIGS. 1-3 it will be seen that the rectangular frame 11 is formed from a pair of elongate side members 15 and channel-shaped end members 16, which are interconnected to said side members as by welding.

In the preferred embodiment the air passing through the frame 11 is heated by means of a plurality of elongate coil elements 17. Importantly, the coil elements 17 are supported along the length thereof by a plurality of transversely disposed rigid ceramic partitions, namely, intermediate partitions 20 and end partitions 21 and 22. Each coil element 17 provides interconnected lengths of elongate coil portions. In the preferred embodiment, two pairs of coil portions 17a and 17b are provided from each elongate coil element 17, by forming said element into a U-configuration, which is then doubled back upon itself. The elongate coil element 17 is provided with terminal connections at each end, which are attached to and supported by end partition 22. The terminal connections are connected to a power supply (not shown).

As shown clearly in FIG. 1 the front and rear coil portions 17a and 17b respectively are supported by the rigid ceramic partitions spaced along the length of the frame 11 and in order to support said coil portions 17a and 17b each of the intermediate partitions 20 and end partitions 21 and 22 is provided with a plurality of apertures generally indicated by numeral 23.

The ceramic partitions 20, 21 and 22 are vertically oriented and are disposed substantially in register along the length of the frame 11. As shown generally in FIG. 2 each partition is defined by end margins 24 and side margins 25. The partitions are attached between opposed frame side members 15 by means of a plurality of tab elements 26 and 27 which, in the preferred embodiment, are formed from the material of said side members 15. As clearly shown in FIG. 2 tabs 26 support each partition across its thickness by overlapping the end margins 24, and the tabs 27 support the partition sides across the width of the partition by overlapping said side margins 25 and to this end the length of the partitions is greater than the clear distance between the tabs. In effect, the tabs 26 and 27 define a pocket adjacent each end of each ceramic partition, which accommodates a tempered leaf spring 30. Opposed leaf springs 30 at each end of each partition provide a seating and cushioning means and the spring height is such that when the ceramic partitions are installed the springs are compressed and a spring force is exerted against each partition tending to cushion said partition against shock.

To facilitate the installation of the partitions the frame can be welded together following emplacement of said partitions and the end springs 30. It is important that the parallelism of the sides 15 be maintained so that the cushioning effect of the springs 30 on the partitions will be adequate and evenly distributed. To this end a plurality of tie reinforcing members 31 are provided, each pair of said members 31 being disposed adjacent one side of an associated partition and extending substantially between opposed frame side members 15. In the preferred embodiment the tie members 31 are lengthwise adjustable to facilitate installation, each tie member consisting of a rod 32 and nut elements 33 which are attachable to said frame side members 15. Said nuts are adjusted at the rod extremities for proper height and spot welded or otherwise attached in place. It will be observed that the tie rod arrangement is particularly useful in those instances where it is objectionable to provide longitudinal flanges on the side members 15 to effectuate stiffening and that said arrangement provides stiffening means for said side members 15.

It will be apparent from the perspective rendering of FIG. 1 that the frame 11 is virtually projection-free, which considerably facilitates installation of the heater unit 10 within the duct 13 and provides that the heater frame 11 fills substantially the entire cross section of the duct. The parallel heating coil portions are distributed substantially evenly over the heater and the absence of projections and flanges insures a minimum obstruction across the available heating area, which results in maximum heating efficiency to the airflow passing over said heating coils.

Claims

I claim as my invention:

1. A blast coil heater unit, comprising:

a. an open frame including opposed elongate side members disposed in spaced relation,

b. a plurality of elongate coil portions disposed in side-by-side relation with said side members,

c. a plurality of transversely disposed, unitary ceramic support partitions disposed in spaced relation along the length of said frame side members and having opposed ends, each partition including a plurality of apertures extending therethrough, said apertures receiving and supporting the coil portions and the partitions being substantially unsupported intermediate their ends,

d. means attaching said ceramic partition ends to said frame substantially without tensioning said partitions including resilient means disposed between said ends and said frame side members to cushion said partitions.

2. A blast coil heater as defined in claim 1, in which:

e. the ceramic partitions are substantially rectangular and include elongate side margins, and end margins extending perpendicularly of the plane of the open frame,

f. the means attaching the partitions to the frame side members include inwardly projecting tab elements,

g. the length of said side margins is greater than the clear distance between said tab elements whereby the tab elements operatively overlap the partition end margins to retain and position said partitions in the frame,

h. the resilient means include spring elements extending generally in the direction of said end margins and disposed between said end margins and said frame side members at at least one end of said ceramic partitions to exert a compressive force on said partitions in a direction parallel with said side margins.

3. A blast coil heater unit, comprising:

a. a substantially rectangular frame including side members and interconnecting end members,

b. a plurality of elongate coil portions disposed in spaced relation to each other and substantially parallel with said frame side members, at least two of said portions being formed from a single coil and having terminal connections at the same end,

c. a plurality of transversely disposed, substantially rectangular ceramic partitions disposed in spaced relation along the length of said frame side members said partitions being substantially in register and including end partitions and at least one intermediate partition, each partition including opposed ends and a plurality of apertures, the apertures of adjacent partitions receiving and supporting associated coil portions, at least two apertures of one of said end portions receiving and supporting said coil terminal connections,

d. means attaching said ceramic partition ends to said frame sides including:

1. a plurality of inwardly extending tab elements formed from the material of said frame side members and disposed on either side of said ceramic partition to operatively overlap and retain said partitions, and

2. a plurality of leaf springs, each spring being accommodated between associated tabs at each end of each partition and providing a resilient cushion between said ceramic partitions and said frame side members, and

e. a plurality of pairs of frame reinforcing tie members extending between said frame side members to maintain the parallel relation of said side members, each pair of tie members being disposed adjacently outwardly of an associated ceramic partition.

4. A blast coil heater unit, comprising:

a. a substantially rectangular frame including side members and interconnecting end members,

b. a plurality of elongate coil portions disposed in spaced relation to each other and substantially parallel with said frame side members, at least two of said portions being formed from a single coil and having terminal connections at the same end,

c. a plurality of transversely disposed, substantially rectangular ceramic partitions disposed in spaced relation along the length of said frame side members, said partitions being substantially in register and including end partitions and at least one intermediate partition, each partition including opposed ends and a plurality of apertures, the apertures of adjacent partitions receiving and supporting associated coil portions, at least two apertures of one of said end portions receiving and supporting said coil terminal connections,

d. means attaching said ceramic partition ends to said frame sides including:

1. a plurality of inwardly extending tab elements formed from the material of said frame side members and disposed in supporting relation to said ceramic partition to operatively overlap and retain said partitions, and

2. a plurality of leaf springs, each spring being accommodated between associated tabs at each end of each partition and providing a resilient cushion between said ceramic partitions and said frame side members, and

e. elongate reinforcing members attached to the frame and tending to maintain the configuration of the frame.