US2881363A - Spark type heater igniter - Google Patents

Description

April 7, 17959 E. DLUzANsKY SPARK TYPE HEATER IGNITER 2 Sheets-Sheet 1 Filled Oct. 10, 1955 April 7, 1959 f E. DLlgzANsKY 2,881,363

SPARK TYPE HEATER IGNITER Filed oct. 1o, 1955 1 2 sheets-sheet 2 r United States Patent O "ice SPARK TYPE HEATER IGNITER Edgar DLuzansky, Indianapolis, Ind., assignor to Stewart- Warner Corporation, Chicago, lll., a corporation of Virginia Application October 10, 1955, Serial No. 539,318

3 Claims. (Cl. 317-83) The present invention relates generally to vehicle heaters of the combustion type and more particularly to an igniter for the burner of such a heater.

One of the objects of my invention is to provide a novel burner, and particularly an igniter therefor, which is well adapted for use in a type of service where it is required that the fuel to the burner be turned on and off in cycles of short duration.

Yet another object of my invention is to provide an improved vehicle heater burner igniter which is extremely resistant to shortening by the accumulation of carbon deposits thereon.

Still another object is to provide a novel burner and starting igniter which greatly reduces the requirement for periodically cleaning the igniter, thereby insuring long periods of satisfactory operation between inspections and servicing.

Still another object is to provide a novel igniter which can be manufactured at relatively low cost by the use of well known and generally practiced techniques.

Still another object is to provide a novel burner and igniter particularly adapted for use in a rapid cycling type heating system.

Other objects and advantages will become apparent from the following description of a preferred embodiment of my invention which is illustrated in the accompanying drawings.

In the drawin-gs, in which similar characters of reference refer to similar parts throughout the several views:

Fig. 1 may be considered as a longitudinal vertical sectional view through a sealed combustion heater which incorporates a burner and igniter embodying features of the present invention;

Fig. 2 is a longitudinal vertical sectional View through the heater burner drawn to larger scale. This view may be considered essentially as an enlargement of a portion of the burner of Fig. l; and

Fig. 3 is essentially a longitudinal sectional View of the igniter shown in elevation in Figs. 1 and 2.

A rapid cycling type heating system is one in which a thermostat in the hot air duct downstream of the heater turns the burner fuel valve olf and -on as is necessary in order to maintain a substantially constant hot air duct temperature with the Ventilating air stream owing continuously. Such systems are effective and simple, but place great demands upon the burner igniter because of the high frequency of the on-off cycles.

A specific control system for a heater of this type is described in the copending application of Frank A. Ryder, for Automotive Vehicle Heating System which was filed August 5, 1955, and which has been given Serial No. 526,714.

The heater shown consists essentially of a generally cylindrical air casing through which Ventilating air passes from right to left. The right-hand end of this case, therefore, may be considered as being connected to a supply of Ventilating air such as a blower for in- Stance, while the left-hand end of the case will ordinarily 2,881,363 Patented Apr. 7, 1959l be connected to a Ventilating air duct system for distributing the heated air to a desired location.

'I'he case 10 has a section at the top thereof cut out as indicated by the line 12, and the opening thus produced is closed by a sheet metal cover 14 secured to the case 10 by screws 16.

Within the case a sheet metal heat exchanger, as indicated at 18, is so positioned that Ventilating air flows thereover, and this heat exchanger is supplied with hot products of combustion by a burner 20 at one end thereof, the exhaust being conducted away through a fitting 21 connected to a suitable exhaust line.

The burner 20 is made up of a tubular adapter fitting 22 which is formed as a portion of the heat exchanger and which has a constricted inner end 24 which forms a loose fit with a ange 26 at the terminal end of a combustion chamber 28.

The combustion chamber 28 is formed essentially as a drawn sheet metal cup and has its base secured as by rivets 30 to a circular plate 32 which in turn is connected by screws 34 across the mouth of a cup-shaped member 36 which may conveniently be fabricated as a die casting since it remains cool during operation of the heater.

At its open end the cup 36 has a flange 38 connected to a similar ange 40 at the outer end of the adapter litting 22 by a split, screw-tightened, clamping band 42. Sealing between these members is effected by a resilient gasket 44.

Air for combustion, from a blower for instance, is brought into the cup 36 through an integrally formed hollow horn extending radially from the body of the cup 36 and terminating in an inlet opening at 46. From the cup 36 the air passes through louvers 48 formed through the plate 32 into the annular space 50 between the combustion chamber 28 and the adapter tting 22. It then passes into the combustion chamber through openings 52 in the side wall of the cup 28 and through openings in the base thereof, one of these openings being centrally located as indicated at 54.

The cup 36 is formed to provide a hollow stem 56 in the center thereof with its end connected to a conventional fuel spray nozzle 58, the tapered nose of which projects through a closed fitting opening in the plate 32 so as to align the nozzle 58 with the opening 54 at the base of the combustion chamber.

The hollow stem in a position just behind the nozzle 58 is provided with a poppet type fuel valve, indicated generally at 72, which opens under the influence of an electromagnet 74 whenever the circuit of this magnet is energized. This permits fuel under pressure to flow from an inlet fitting 76, through cored and intersecting drilled passages 78 and A80 to the interior of the hollow stem and thence around the valve 72 to the nozzle 58.

The fuel and air mixture Within the burner is ignited by a high tension electric spark between an insulated electrode and a grounded electrode 92. The insulator 94 for the electrode 90 extends through an opening 96 in the base of the cup 36 and through aligned openings 98 and 100 in the plate 32 and the base of the combustion chamber cup 28. Within the combustion chamber, the high tension electrode 90 is bent to one side as indicated at 102 and is spaced from the end of the grounded electrode 92 by an appropriate amount. The opposite end of the grounded electrode is welded to the base of the combustion chamber cup as at 104. Preferably the electrode 90 at the burner end should slope downwardly so that fuel collected thereon will tend to run downwardly and olf the tip of the electrode rather than accumulating thereon.

The high tension electrode 90 is formed as a portion of a removable element or plug which includes a generally cylindrical ceramic sleeve which forms the insulator 94,.

Near its outer end, this ceramic element is provided with a spherical enlargement or head 106 which ts into a socket 108 formed at the opening 96 through the base of the cup k36. Soft metal gaskets 110 are fitted above` and below this head and the assembly is secured in position by alscrew retained clamp vfitting 1,12 attached to the outside back surfaceof the cup' 36. In order to prevent rotation of the insulator within the cup 36 and hence misalignment of the offset electrode 102 with respect to the grounded electrode 92, the spherical head 106 is slotted longitudinally as at 114 and isinserted with this slot engaging a complementary tongue 116 formed within the socket 108. v

The insulator and electrode assembly, or spark plug, has a metal rod 118 extending axially therethrough with a terminal 120 at one end for the attachment of a high tension electric cable. The opposite end of the rod 118 extends into a recess 122 formed into the end of the ceramic body. The recess 122 in turn communicates with a larger recess 124 at the end of the ceramic body. Both recesses are shown as being cylindrical and coaxial and, therefore, form a step 126 where they join. The electrode 90 previously mentioned is formed of .a small diameter wire of suitable electrode alloy and has one welded to the end of the rod 118 within the smaller recess 122. Its opposite end extends well beyond the end of the ceramic body and is bent to one side as previously described. n i

Suitable dimensions in inches for the several elements described above are as follows. The diameter of the cylindrical portion of the ceramic body is about 0.44. The recesses 122 and 124 are each about 0.5 long, and have diameters, respectively, of 0.26 and 0.28. The rod 118 extends into the recess 122 about 0.25 and before being bent the wire 90, which has a diameter of 0.051, projects about 0.51 beyond the end of the ceramic body. The bend is at an angle of about 72 and is positioned about 0.375 beyond the end of the insulator. The thickness of the thin shell which encloses the recess 124 is, therefore, 0.08 and the clearance between the wire 90 and the side wall of the recess 124 is about 0.115. In use, the gap between the grounded electrode and the insulated electrode is about 0.085.

From these dimensions it will be apparent that, as compared with ordinary heater spark plugs, the wire 90 is very small and the clearance between it and the ceramic shell is extremely great for a long distance inwardly of the end of the insulator. Note for instance that the space between the wire 90 and the ceramic shell is almost twice the sparking gap.

This arrangement has been found to be important in giving the spark plugs long service life without the necessity for cleaning. This is because the small wire 90 does not present very much of a surface for the accumulation of the liquid rfuel which is the source of the carbon. Also, because the clearance between the wire and the insulator is great, a large accumulation of carbon is necessary before the center electrode is grounded to the burner casting by the hn of carbon along the exterior surface of the ceramic body. The deep recess with the step in the middle produces a region of almost no turbulence well inwardly of the end of the insulator and thus almost no fuel is carried to the bottom of this pocket to form a conducting bridge of carbon even though some will be formed upon the wire and upon the interior wall of the pocket for some distance inwardly of the end of the insulator.

By making the recess at the end of the ceramic body with the step 126, the end of the insulator is much less fragile than it would be if the entire recess had the same diameter as the open end. Furthermore, since most of the carbon deposit will form immediately adjacent to the open end of the cavity, the clearance between the electrode wire and rod 118 and the insulator wall within the cavity 122, although less than within the cavity 124,

i 4 is nevertheless suflicient to prevent shorting within this region until after shorting has finally occurred at or near the open end of the cavity 124.

From the above description of a preferred embodiment of my invention it will be apparent that the igniter is simple and easy to manufacture and use, and that it has an exceptionally long service life principally because carbon deposits which form thereon must becomeextremely great before the igniter fails to function properly due to shorting of the high tension electrode to ground.

Furthermore, within the zones where relatively small carbon accumulations might cause shorting, such accumulations are prevented by preventing the entry of fuel into these regions.

It will also be evident that the dimensions given are illustrative and that variations and substitutions may be made in the structure shown and described without departing from the scope or spirit of the invention and that, therefore, the scope of the invention is to be measuredv by the scope of the following claims.

Having described my invention, what I claim as new and useful and desire to secure by Letters Patent of the United States is:

l. In 'a heater igniter, means forming a generally cylindrical body of heat resistant insulating material, said body having a spherical head portion thereof formed with a slot to aid in securing the igniter to a burner in a predetermined orientation, -one end of said body being adapted to extend into the heater burner, said one endA having a deep substantially flat bottomed recess extending thereinto, a conductor extending axially through said body and terminating within but near the bottom of said recess, a small diameter wire secured to the end of said. conductor, said wire extending outwardly through said recess coaxial therewith to a position well beyond the' end of said body and terminating in a sparking electrode, the depth of said recess being such that a carbon bridge cannot form across the bottom thereof during the time required to form a carbon bridge between the wire and the mouth of said recess, and the distance between said wire and the wall forming said recess being at least one-eighthinch.

2V. In a heater igniter, means forming a generally cylindrical body of heat resistant insulating material, said body having a portion thereof formed to aid in securing the igniter to a burner, one end of said body being adapted to extend into the heater burner, said one end having a deep coaxial recess extending thereinto to an annular step and a second substantially flat bottomed recess extending thereinto beyond said step, said second recess having a diameter less than said iirst recess, a conductor extending axially through said body and terminating at one end within said second recess, a small diameter wire secured to the end of said conductor within said second recess, said wire extending outwardly through the rst said recess coaxial therewith to a position well beyond the end of said body and terminating in a bent portion, the depth of the rst recess being in excess of three times the distance between said wire and the wall forming said first recess, and the distance between said wire and the wall forming said first recess being at least one-eighth of an inch.

3. In a heater igniter, means forming a generally cylindrical body of heat resistant insulating material, said body having a spherical head'portion thereof formed with a. slot to aid in securing the igniter to a burner with a certain orientation, Vone end of Asaid body being adapted to extend into the heater burner, said one end having a deep coaxial recess extending thereinto to an annular step and a second substantially flat bottomed recess extending thereinto beyond said step, said second recess having a diameter less than said first recess, a conductor extending axially through said body and terminating at one end within said second recess, a small diameter wire secured to the end of said conductor within said second recess,

said wire extending outwardly through the rst said recess References Cited in the file of this patent coaxial therewith to a position well beyond the end of said body and terminating in a bent portion, said wire UNITED STATES PATENTS including said bent portion having a downward component continuously to the end thereof when the igniter 5 1550837 Mueller Aug' 25 1925 has said certain orientation, the depth of the rst recess 115,873 Powers May 3 1938 being in excess of three times the distance between said 2,117,781 WllsOn May 17, 1938 gire and tilde W51 fomilrllg Sailll rst recessder distance 2,423,809 De Lancey Juiy s, 1947 etween sal W1re an t e Wa ormmg sal st recess 2 4 3 being at least one-eighth of an inch, and the depth of 10 Zg ulert June 29 1948 said second recess beyond said first recess being of the arm Oct' 12 1948 order of four times the distance between said Wire and 2,645,082 Sarto July 14, 1953 the Wall forming said second recess.

mman STATES PATENT oFFICE 4CERTHPICATE OF CORRECTION Patent Nm ,2,88ly363 April '7, 1959 Edgar D 'Luzansky It is herebiT certified that error appears in the-printed specification o the above 'numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column ll, line 25)Y for "shortening" read m .snorting m; column 3, line 25, for OnaA Welded," read 4- onel and Welded m-L,

Signed and sealed this lltn day of August 1959.

SEAL) Attest:

KARL AXLINE ROBERT C. WATSON Atteeting Officer Commissioner of Patents UNTED STATES PATENT OFFICE l CERTIFICATE 0F vCORRECTION Patent No, ,2,881,363 April 7, 195e It is herebj1 certified that error appears in the-printed specification o the above numbered patent requiring correction and bha-l'. the said Letters Patent should read as corrected below. f

Column l, lineA 25, for "shortening" read w snorting m; column 3, line 25, for one Welded," read done end Welded mf-L,

Signed and s'ealec' this 11th dey of August 1959..

(SEAL) Attest: KARL EL, .AXLINE ROBERT C. WATSON Attesting Oficer Commissioner of Patents

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