US2998806A - Booster heater - Google Patents

Description

Sept. 5,. 1961 v. N. TRAMONTINI BOOSTER HEATER 5 Sheets-Sheet 1 Filed May 22, 1958 m m V M Sept. 1961 v. N. TRAMONTlNl 2,998,806

BOOSTER HEATER Filed May 22, 1958 N 5 Sheets-Sheet 2 q Sept. 5, 1961 v. N. TRAMONTlNl BOOSTER HEATER 5 Sheets-Sheet 5 Filed May 22, 1958 VEEA/O/Y N EAMONT/N/ 1 rrO/ZNEV Sept. 5, 1961 v. N. TRAMONTlNl 2,998,805

BOOSTER HEATER Filed May 22, 1958 5 Sheets-Sheet 4 a fNVENTOE VEE/VO/V M 7PAM0/vr/M Sept. 5, 1961 v. N. TRAMONTlNl BOOSTER HEATER 5 Sheets-Sheet 5 Filed May 22, 1958 United States Patent 6 2,998,806 BOOST-ER HEATER Vernon N. Tramontini, Indianapolis, Ind., assignor to Stewart-Warner Corporation, Chicago, llh, a corpora tion of Virginia I Filed May 22, 1958, Ser. No. 737,152 S'Claims. (Cl."'l22 --136) The present invention relates generally to combustion heaters for heating water or other liquids and, more particularly, to special purpose liquid heaters of the type commonly referred to as booster heaters.

The most commonly used type of heating system for automobiles is one in which the hot engine coolant is used for heating. In these systems, the liquid coolant flows from the engine to a heater heat exchanger and back to the engine. A blower provided for the purpose circulates ventilating air through the heat exchanger and into the occupied space so as to raise the temperature therein to the desired level. One of the difficulties encountered with such heating systems is that for a considerable period after the automobile engine has been started, substantially no heat, or insuflicient heat, will be supplied by the vehicle heater because of the low temperature of the engine coolant. In general, the operation of such heating systems is not satisfactory until the temperature of the engine coolant rises to about 150 or 160 degrees F.

A booster heater is connected in series in the hose line between the engine and heater heat exchanger, and acts to supply heat at a high rate to the engine coolant during the initial period of engine operation and until the engine reaches its proper operating temperature. The booster heater, therefore, serves important functions. It insures that the temperature of the coolant arriving at the heater heat exchanger will be at a satisfactorily high level even though the temperature of the coolant leaving the engine is too low to be useful for compartmerit heating purposes. Additionally, it shortens the engine warmup period, and conserves fuel, since the booster heater uses the engine fuel more efficiently for heating the engine coolant than does the cold heavily choked engine.

One of the objects of my invention is to provide such a booster heater which may be supplied at relatively low cost in package form for installation in almost any conventional automotive vehicle.

Yet another object of my invention is to provide an improved booster heater in which the heat exchange portion may be formed at low cost and substantially en tirely of seam-welded sheet metal elements.

Still another object is to provide a novel low-cost booster heater of high efiiciency which is adapted for -mounting in any of several positions and which occupies a minimum of space.

Yet another object is to provide a novel booster combined heat exchanger and safety switch structure which is directly responsive to unsafe operating conditions of the heat exchanger.

Yet another object is to provide a novel combined heat exchanger of the type outlined above and safety switch which operates to protect need for any thermostatic actuating element other than .the heat exchanger itself.

the heater without the Still another object of the invention is to provide a =novel booster heater gas to liquid heat exchange struc ture which provides a relatively long travel path for the hot products of combustion in heat exchangerelation to the heat exchange surface [within a minimum of space and in an easily serviceable structure.

Other objects and advantages will become apparent from the following description of apreferred embodi- "ice ment of my invention which is illustrated in the accompanying drawings.

In the accompanying drawings in which similar characters of reference refer to similar parts throughout the several views:

FIG. 1 is a perspective view of the heat exchanger and burner portion of a booster heater incorporating the present invention;

FIG. 2 is a vertical longitudinal medial sectional view through the heater of FIG. 1;

H6. 3 is a perspective view of a bafile located within the heater, this baffle being-illustrated in elevation in FIG. 2;

P16. 4 is a plan view of a of which are used in forming structure of FIG. 3;

FIG. 5 is a perspective view of the blank of FIG. 4 after it has been shaped to approximately its final form;

FIG. 6 is a transverse sectional view through the heater and may be considered as taken in the direction sheet metal I blank, several the major portion of the r of the arrows substantially along the line 66 of FIG.

FIG. 7 is a fractional sectional view of a portion of the structure illustrated in FIG. 2 drawn to larger scale so as to disclose details of construction;

FIG. 8 is a side elevation of an alternative heater similar to that forming the subject matter of FIG. 1, but incorporating an additional feature of my invention;

FIG. 9 is a top view drawn to larger scale of a safety switch incorporated in the heater of FIG. 8, with a portion of the mechanism broken away so as to reveal the underlying structure in greater detail;

FIG. 1C- is an end view of the switch structure of FIG. 11 is a longitudinal medial sectional view which may be considered as taken in the direction of the arrows substantially along the line ll-llof FIG. 9; and

FIG. 12 is a simplified electrical circuitdiagram illustrating a representative arrangement for operating the heater of the present invention, including the safety switch of FIGS. 9' to 1:1 and other ancillary equipment,

The heater, as shown, is generally cylindrical and is about four inches in diameter by eighteen inches, or so, long. mately one foot long. These dimensions are not critical, nor are they intended to be limitative; they are given here merely for the purpose of giving the drawings an approximate scale.

The burner is shown at the left hand end of the structure as seen in FIGS. 1 and 2, the principal elements thereof being disposed within or attached to a cup-shaped, diecast housing 8. Gasoline or other motor fuel is introduced to the burner by way of a fitting 10 which it is intended will be connected into the automobile fuel line between the carburetor and the engine fuel pump. The fitting thus receives fuel under a relatively low pressure, of the order of 3 to 5 poundsper square inch. From the fitting, the fuel passes by way of a drilled passage -12 to a nozzle 14 at the center of the housing 8, this passage including an electrically actuated fuel valve. This valve is normally closed, but is opened when a solenoid, indicated at 16, is electrically energized.

Fuel sprayed from the nozzle 14 is ignited by a pair of sparking electrodes 18, one of which is grounded, the other being let out through a suitable ceramic insulator to a terminal at 20. Combustion takes place within a generally cylindrical burner tube 22 into which the nozzle extends and which terminates at its downstream end in an outwardly turned flange 24, which has its peripheral edge turned backwardly to provide a short cylindrical surface 26 of larger diameter as is best seen in FIG. 7.

Of this, the heat exchange portion is. approxisheet metal shell 30. The left hand end of the enclosing shell 30 is belled outwardly, and is provided with a gasket which in turn is sealed against the end of the housing8 by a circumferential clamping band 31.

Air for combustion is introduced from a blower (not shown) by Way of a line 32 so that it enters the housing 8 tangentially. From the housing 8, the combustion air flows into the combustion tube 22 principally by way of an annular chamber 36 formed between the burner tube 22 and the surrounding shell 30, and thence through holes 38 which are punched through the side Wall of the burner tube 22 at appropriate locations.

The burner structure requires no additional description here, since the present invention is not concerned with its specific construction.

The same cylindrical shell 30, which encloses the burner tube 22 at its left hand end, continues to the right for the full length of the heat exchange portion of the heater. An inner sleeve 42, which is approximately one foot long, is formed to cylindrical contour, and has an external diameter substantially equivalent to the internal diameter of the shell 30. The sleeve 42 is extensively fluted longitudinally throughout its central region and i almost to the ends where the flutes blend into the cylindrical portion as is indicated at 44. Thus the fluted portion of the tube 42 has a considerably smaller overall diameter than the ends thereof. This is well illustrated in FIG. 6 where the flutes are indicated by the numeral 46, and the intervening portions between the flutes by the numeral 48.

After being formed as described above, the tube 42 preferably has its ends sized by stretch forming and is slid into the shell 30 so that the right hand ends of the two members are approximately flush. The two tubes are then seam-welded together around their entire periphery at both ends of the inner tube 44. A flanged sheet metal closure member 50 is then pressed into the right hand end opening of the structure and its flange welded around its periphery to the surrounding metal so as to isolate the interior of the structure at the right hand end. This closure 50 is provided with an exhaust fitting 52 adapted to be connected to an exhaust line which, in use, extends downwardly away from the heater to a position below the engine compartment, and thence rearwardly a short distance so as to insure that exhaust gases will not be taken into the occupied space of the vehicle. At its left end, the inner cylindrical surface of the inner sleeve 42 fits the external surface of the burner flange 26 previously mentioned.

The structure described so far provides a closed annular space 54 between the shells 30 and 42 which is bounded by a smooth exterior wall and a corrugated interior wall. Access is provided at the right hand end near the bottom of the heater by a tangential fitting 56 welded to the exterior shell 30 and opening through into the annular space 54. The opposite end of the space 54 at the top of the heater is similarly connected to an outlet fitting 58. These fittings are connected to hoses 60 and 62, respectively, with the inlet hose 60 leading to the outlet fitting on the engine cooling jacket, while the hose 62 leads from the fitting 58 to the heat exchanger inlet of the vehicle heater.

The outlet fitting 58 is formed so that it serves also as the housing for a thermostatic element 64 which is used for turning the heater burner on and off, depending upon the requirement for heat. This thermostatic element may be of any suitable type which responds to the temperature of the water leaving the booster heater. Incidentally, the term water" as used herein refers to the engine coolant which customarily comprises a solution of water and a freezing point depressant.

In the version of the heater shown in FIGS. 1 and 2, this thermostat may typically be set so that it opens an electrical circuit whenever the water temperature rises to approximately 160 F. and closes the circuit whenever the temperature drops below F.

A second thermostatic switch is indicated at 66. For the present purpose, it may be considered to be any suitable thermostat which is sensitive to the temperature of the outer shell 30 in the region of the outlet fitting 58. This switch is to be connected into any suitable safety circuit so that it turns off the heater whenever the shell temperature rises to approximately 245 F. Operation of this switch is an indication of an overheat condition due to the absence of water in the upper portion of the water jacket. This may be caused by a shortage ofwater in the engine cooling system, or to a failure to open the water valve at the inlet of the space heater following an extended period of heater inactivity during which air has collected in the heater water jacket.

Because of the tangential water connection to the jacket 54, the engine coolant flowing therethrough will take a spiral path which brings it into intimate heat exchange contact with the inner corrugated shell 42.

The hot products of combustion from the burner also are caused by a baffle 68 to follow a spiral path making more than six turns while passing the length of the heat exchanger. This batfie is formed of sheet metal. It is shown in place in FIG. 2, and its construction may best be seen in FIG. 3. It closely fits the wall of the inner shell 42, its periphery being notched regularly, as at 70, so as to accommodate the flutes 46. The fit need not be tight since some leakage of gas around the edge of the battle will not be objectionable. At one end, as is best shown in FIG. 3, the spiral element is welded to a sheet metal book 72 which fits over the lip 26 at the burner outlet. In assembling the device, therefore, the spiral baffle 68 is pushed partway into the heat exchanger, after which the lip of the burner is engaged in the hook 72 and the burner pushed into place and clamped so as to complete the assembly. The hook properly locates the bafiie longitudinally within the heater, and although the baflie does not form a tight fit with the heat exchanger, its general springiness will insure sufiicient engagement so that it will not rattle in use.

The spiral bafiie 68 is formed as follows: as illustrated in FIG. 4, the sheet metal disc there shown is indicated by the numeral 74. This disc has a diameter somewhat larger than the finished bathe, and has a circular opening 76 at the center. Its periphery is provided with the notches 70 which accommodate the flutes of the inner shell in the finished baffle. This disc is radially sheared as at 78 from the opening 76 to the periphery.

After this blank has been formed as indicated, it is placed in a fixture and stretched longitudinally to provide the element shown in FIG. 5 which, as appears, forms one turn of a spiral. This stretching action reduces the overall diameter of the element, and substantially eliminates the straight-through hole along the center line.

One of these spiral elements, as shown in FIG. 5, is then placed in a fixture with an identical element in tandem relationship oriented so that they overlap slightly at their adjacent edges by rotating the edge of one relative to the other by the spacing of one of the notches 70 when the two are inserted into the fixture. The overlapping edges are then resistance-welded together so as to provide a spiral element having two full turns less the spacing between adjacent notches 70. This assembly operation is continued until, as shown in FIG. 3, seven of these elements are so joined. Although it is not critical, the joining of seven elements in this manner in the particular heater shown producesa spiral having six and one-half turns since the blanks 74, as is best seen in FIG. 4, have twelve equally spaced notches around their periphery.

A modification of the heater just described is illustrated in FIGS. 8, 9, 11, and 12. A particular advantage of this version of the heater is that it is better adapted for operation under severe conditions where water, on occasion, may be absent from the water jacket. As shown in FIG. 8, the exterior shell 30a, which is the counterpart of the shell 30, is rolled near the outlet fitting 58 so as to form a radially outwardly extending circumferential bead at 80. A section through this bead is illustrated in FIG. 11. This convolution in the exterior shell greatly'enhances the capacity of the heater to absorb thermal shock. As an example, in the event that combustion is started within the heater under conditions where water is not present throughout the water jacket, the inner shell 42 is heated to a high temperature while the outer shell 39a remains relatively cool. The inner shell, therefore, expands longitudinally, and stretches the outer shell by slightly unrolling the bead at 80. Were it not for this bead, a relatively high order of stress would be set up inthe heater structure since the inner shell is solidly anchored to the outer shell at its ends. FIGS. 9, and 11 show a safety switch forming a portion of the present invention which takes advantage of the fact that any differential heating as between the inner and outer shells due to a shortage of water in the water jacket will increase the dimension across the bead 80.

A hat-shaped clip 82 is welded to the shell 38 at one side of the bead 8i), and its counterpart 84 is welded to the shell at the other side of this bead. One of these, the clip 84, carries a machine screw securing a stack of insulating washers and a pair of terminal strips 86 and 88 insulated from each other and from ground. One of these, the strip 86, is turned vertically upwardly on the end adjacent the bead 80, and is provided on the side toward the bead with a fixed contact 90. The other terminal strip 88 bears against and is in electrical contact with a spring metal leaf 92 which extends upwardly in a position between the contact 90 and the bead 80. At its upper end the leaf 92 carries a contact 94 which is normally spring-pressed into engagement with the contact 90. The upper end of leaf 92 is somewhat wider than the end of the terminal strip carrying the contact 90, as may be seen in FIG. 9.

A strip of insulating material 96 is anchored at one end by a screw 98 to the other clip 82 and extends over the bead 80 and is provided near its free end with a T slot 100. The narrow portion of this slot clears the side edges of the terminal member 90, while the wider portion clears the side edges of the somewhat wider leaf 92. The junction between the two portions of the slot provides a pair of shoulders 102 which engage the back surface of the spring metal leaf 92 whenever the clips 82 and 84 move apart some preset distance.

A hat-shaped cover 104 formed of sheet metal protects the contacts and is held in place by engaging its lower outturned side edges beneath stuck out tabs 106 formed in the lower wings of the switch mounting membore 82 and 84. The cover is therefore securely held in place but its retaining means does not inhibit slight longitudinal relative movement of the switch mounting members 82 and 84. As is seen at 108 in FIGS. 9 and 11, the central lower portion of the cover member 104 is cut away so as to clear the bead 80.

This switch operates in the following fashion: Under normal conditions, when the temperature of the inner shell 42 and the outer shell 30a are approximately the same regardless of what this temperature may be, the contacts 90 and 94 will be spring engaged because any expansion or contraction of the inner shell will be accompanied by similar change in length of the outer shell 30a. On the other hand, if for any reason, such as a shortageof water in the water jacket of the heater, the inner shell is heated to a considerably higher temperature than the outer shell, the inner shell will expand longitudinally more than the outer shell, thereby stretching the outer shell and slightly unrolling the bead at 80. This moves the switch mounting members 82 and 84 apart so that the shoulders 102 of the strip 96 catch behind the spring metal contact carrying member 92, thereby pulling the top of this member toward the right as seen in FIGS. 9 and 11, so as to separate the contacts 90 and 94. Subsequently, whenever the shell temperatures have reasonably equalized, the contacts will return to their normally closed condition.

A typical circuit incorporating the elements of the heater and the switch just described are illustrated in FIG. 12. Here the automobile battery is indicated at 110, one side of this battery being grounded, the other side leading through the engine ignition switch 112 to the engine ignition system (not shown) and to one side of the booster on-off switch 114. The other side of this switch is connected through a fuse 116 and the thermostatic switch 64in series, to the contact 90 of the switch shown in FIGS. 9 to 11.. The other contact 94 is connected to a line 118 which energizes the electrically actuated fuel valve 16 and an electric motor 120 which drives a combustion air blower the outlet of which is connected to the line 3 2. The blower motor also drives a cam 122 which acts' to make and break a set of contacts 124. .The primary 126 of an ignition transformer has one end con-' nected to the line 118, the other end being grounded through the make and break contacts 124, these contacts being protected by a parallel capacitor 128 which also increases the current through the transformer in a well known manner. The secondary 130 of this ignition transformer has one side connected to the line 118, the other sidebeing connected to the terminal 20 of the insulated sparking electrode, the other electrode being grounded.

Assuming the engine ignition switch is closed, the heater is put into operation 'by closing the switch 114. This energizes the fuel valve and supplies fuel to the nozzle 14, and simultaneously energizes the combustion air blower and produces sparking at the spark plug electrodes 18. Combustion, therefore, immediately takes place, and the temperature of the water passing through the jacket 54 begins to rise. Whenever the temperature of the water at the outlet fitting 58 reaches 160", and this occurs quite quickly, the thermostatic switch 64 will be opened, thereby deenergizing all of the heater electrical equipment, with the result that combustion ceases. Usually the water temperature now will drop below 140 and the switch 64 will reclose and restart the heater. This is because the water leaving the booster will reach 160 considerably before the engine water temperature reaches 140. Depending upon conditions, the booster ordinarily will cycle oflf and on a few times before remaining off.

If, due to a shortage of water in the heater water jacket, the temperature of the inner shell rises substantially above that of the outer shell 30a, safety switch con-,

tact 94 will be separated from the contact 99 as described,

without departing from the spirit or scope of the invention, and that, therefore, the scopeof the invention is to be determined from the scope of the following claims.

I claim:

1. A combustion heater including a heat exchanger defining an annular liquid heat exchange passage and burner means coupled to the heat exchanger for heating the liquid flowing through the passage, the improvement comprising an external casing for the heater formed by an outer cylindrical sheet metal shell of uniform diameter which is part of the heat exchanger, an inner shell having a longitudinal center portion of less diameter than the outer shell, said inner shell located within the outer shell downstream of the burner means, and having flared ends bonded to the outer shell to provide the annular passage between the shells, the burner means including a combuslion chamber tube of smaller diameter than said outer shell and having an integral, outwardly turned flange terminating in a laterally directed peripheral portion of a diameter slightly less than the diameter of said outer shell, said combustion chamber tube being inserted within said outer shell with said laterally directed portion of said flange contacting in sealing relation and adjacent the flared end of the inner shell to form with said outer shell an annular air supply chamber, air supply means to said chamber and air outlet means in said tube for passage of air therethrough.

2. Apparatus as claimed in claim 1 wherein said inner shell is fluted longitudinally throughout its central portion and a spiral baflie is positioned within said inner shell and extends the length of the reduced center portion of the inner shell with the periphery of the baffle being serrated so as to mate substantially with the flutes of the inner shell.

3. Apparatus as claimed in claim 1 further including a circumferential bead formed in a portion of the outer shell defining the annular liquid passage, and means responsive to the dimensional change of said bead to detect excessive heating of said heat exchanger.

References Cited in the file of this patent UNITED STATES PATENTS 1,613,615 Lippert Ian. 11, 1927 2,022,728 Lieberherr Dec. 3, 1935 2,531,459 Marshall Nov. 28, 1950 2,722,180 McIlvaine Nov. 1, 1955 2,783,755 MacCracken Mar. 5, 1957 2,847,953 Ernst Aug. 19, 1958 FOREIGN PATENTS 664,168 Great Britain Jan. 2, 1952 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,998,806 September 5 1961 Vernon N. Tramo ntini It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 8, line 9, for "dimension" read dimensions a Signed and sealed this 3rd day of April 1962 (SEAL) Attest:

ERNEST W. SWIDER DAVID'L. LADD Attesting Officer Commissioner of Patents

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