CA1036924A - Catalytic heater - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A heater device for preheating liquid coolant of an internal combustion engine having an elongate cylindrical heat exchanger with an elongate catalytic heater assembly releasably mounted generally coaxially therein. The heater assembly has a catalytic impreg-nated fibrous material wrapped around an elongate porous ceramic tube with closed ends and an injector which dis-charges vaporized fuel into the interior of the ceramic tube.

Description

103~3~Z4 rhis inventlGr~ relat~es to a devlce for pre-heating the liquid cc,olant Or an i.nt;ernal com~ustlon engine and rr.OIe particu].ar]y to such a rlevice ~rith a flameless catalytic heater.
Objects of this inventiorl are to provide a catalytic heater device which ls saf`e, corlpact, of economical manufacture and assernbly, and has a long maintenance-~ree service life.
These and other objects, feat;ures, and advan-tages Or this invention will be apparerlt fro~ the fol-lowing description, appended claimsJ and accompanying drawings in ~lhich:
FIG. 1 is a slde view parl;ially ln section of a catalytic heater embodying thls lnverltion;
FIG. 2 is a top view of the catalytic heater of FIG. 1;
FIG, 3 is a bottom view Or the catalytic heater Or FIG, 1;
FIG. 4 is a fragmentary sectional view on 20 line 4-4 of FIG. 2;
FIG. 5 is a fragmentary view on line 5-5 of FIG. 3i - FIG, 6 is a semi-diagrammatic view Or the catalytic heater of FIG. 1 connected to both a control 25 box and a fuel pump connected to the gasoline line of a motor vehicle;

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103~9\24 FI~. 7 is a sche~,atic diagra~l o~` the electric control circuit ~or both the catalytic heater and fuel pump of ~Ia~ 6;
FIG. 8 is a side vie~J partially ln sectlon of a modified catalytic heater embodying t}~is invention;
FIG 9 is a semi-diagran~atic vie~l of the catalytic heater Or FIG. 8 connected to both a control : box and a fuel purnp cor-nected to the gasoline line Or a motor vehicle;
10FIG. 10 is a schematic diagram Or an elec-tronic control circuit for the catalytic heater and fuel pump of FIG. 8; and FIG. 11 is a sectlonal vie~r of the fuel pump of FIGS. 6 and 9.
15Referring in more detail to the drawings, FIG. 1 illustrates a catalytic heater 10 ernbodying this invention having a heat exchanger jacket 12 en-circling a catalytic heater assembly 14. Heat ex-changer 12 has a cylindrical charnber 16 defined by an inner metallic tube 18, an outer metallic tube 20 en-circling the inner tube, and metallic end rings 22 interposed between the tubes and fixed thereto, such as by brazing. Engine liquid coolant enters chamber 16 throu~h an inlet conduit 28 fixed to outer tube 20 ad~acent the lower end of charnber 16 and flows from : chamber 16 through an outlet conduit 30 fixed to outer tube 20 adjacent the uyper end Or chamber 16. A
check valve 32 in inlet conduit 28 prevents liquid coolant from flowing out of chamber 16 through the inlet conduit. A plurality of slots or windo~rs 34 and i -2-1036~Z~

36 adjacent opposed ends of inner tube 18 allows at-mospheric air to flow through the tube adjacent the outer periphery of heater assembly 14.
As shown in FIGS. 1 and 4, heater assembly 14 has a porous ceramic tube 38 with upper and lower end caps 40 and 42 fixed thereto. A layer of a fi-brous material 44 is wrapped around ceramic tube 38 and impregnated with a catalytic agent, such as plati-num. A suitable fibrous material is the ceramic felt T-3 (Trademark) fiber produced by Refractory Products Company of Carpentersville, Illinois. A nichrome wire 46 extends axially along the outside of tube 38 beneath the layer of fibrous material 44 to provide an elec-trical resistance heating element for preheating the catalytic heater assembly. One end of nichrome wire 46 is connected to an insulated binding post 48 mounted on tube 18 and the other end of wire 46 is connected to tube 18 and a ground lead wire 50 by a machine screw 52.
Upper end cap 40 of heater assembly 14 has a central depression or cup 54 therein which extends into the interior of the upper end of ceramic tube 38. A
temperature responsive or thermostatic switch 56 with insulated lead wires 58 and 60 connected thereto is pot-ted in the cup 54 of end cap 40 by a suitable potting material 56, such as Acid-Alk Mortar No. 33 (Trademark) available from Sauereisen Cements Company of Pittsburgh, Pennsylvania. A fuel injector 62 with a union 64 on the lower end of an evaporator tube 66 extends through *

~ -3-103~:~9~4 and is fixed tG lower end cap 42 ol heater assembly 14 to discharge va~orized fuel into the :LnteriGr of ceram-ic tube 38 adJacent the longitudinal mid portion thereof.
Heater assembly 14 is mounted substarltially 5 coaxially in inner metallic tube 18 by an upper locator disc 67 and a lower locator disc 68. As shown ln FIGS
1 and 2, u~per locator disc 67 bears on the uE~per end of heater assembly 14 and has three circumferentially spacedJ inwardly and downwardly struck tabs 70, which 10 engage the outer periphery of upper end cap 40, and a central aperture 72 providing clearance for thermostatic switch 56. Locator disc 67 abuts on three circu~eren-tially spaced, inwardly struck tabs 74 in the upper end of inner tube 18. As shown in FIG. 1, heater assem-15 bly 14 is yieldably urged into engagement with upper locator disc 67 by a spring 76 interposed between and bearing on lower locator disc 68 and lower end cap 42 of the heater assembly. As shown in FIGS. 1, 3 and 5, lower locator disc 68 is releasably retained in tube 20 18 by three circumferentially spaced tabs 78 on the disc 68 ~rhich are received in three circumferentially t spaced reentrant slots 80 in the lower end of tube 18.
Rotating of lo~rer disc 68 for installation in and re-- moval from tube 18 is facilitated by a pair Or holes 81 25 in the disc 68. A rubber grommet 82 encircles injector 62 and is received in an aperture 84 in locator disc 68 to coaxially position the lower end of heater assem-bly 14 in tube 18.

,._ 103~i924 ~ Ihcn catalytic heater 10 is installed to preheat the liquid coolant Or an internal com~ustion englne, fuel ~n~ector 62 is connected to a source Or pressurized hydrocarbon fuel, such as gasoline or li-quified petroleum gas. As shown in F'IG. 6, when de-vice 10 is installed in a motor vehicle, gasollne may be supplied to in~ector 62 under pressure by a separate electric fuel pump 84 with an inlet connected by a line 86 through a tee 88 to the fuel line 90 of the vehicle (not shown) between the gasoline tank and the ruel pump of the internal combustion engine The outlet of pump 84 is connected to injector 62 through a fuel metering orifice 92, lines 94 and 96, and male coupling 98. As indicated by arrow 100 (FIGS, 1 and 6), cata-lytic heater 10 should be mounted so that the longi-tudinal axis of heater assembly 1l~ extends generally vertically with fuel in~ector 62 at the lower end there-of, The catalytic heater 10 is mounted at a vertical ::~ height between the vertically highest and lowest points in the cooling system of the engine and preferablycloser to the highest point thereof so that the liquid coolant will be circulated through the heater and engine when the heater is operating, The inlet conduit 28 of . heat exchanger 12 is connected by a hose 102 to the engine cooling system at a low point thereof such as the engine drain opening or through a core plug in the side of the block of the engine. The outlet conduit 30 of heat exchanger 12 is connected by a hose 104 to the engine cooling system at a higher point than the inlet ,, ,, 1036g24

2~ such as a~ the connectlon of tt)e heater lnlet hose to the cooling system Or the vehicle.
~ s shown in FIGS. 6 and 7, a ccntrol box 106 is electrically connected to catalytic heater 10 to 5 control the runctioning thereof`. Control bCY. 106 has a front panel lOo with a master power swltch 110 mounted thereon and a timer switch 112 mounted therein with a manually movable actuator lever 114 which proJect~
through a slot 116 in control panel 108. One contact of power switch 110 is connected through a lead line 118 to the positive pole of a battery 120 and the nega-tive pole of the battery is connected to ground of the vehicle frame by a lead line 122. The other contact of switch 110 is connected to both one contact of switch 15 112 by a ]ead line 124 and to one contact of temperature responsive switch 56 by lead line 60. The other con-tact of temperature responsive switch 56 is connected by lead line 58 to the solenoid actuating coil 126 of electric fue] pump 84 which is grounded by a lead line 20 127. The other contact of timer switch 112 is connected by a lead line 128 to one end of nichrome wire resistance heating element 46 through binding post 48 and the other end of the nichro~e wire 46 is grounded through lead line 50.
In using catalytic heater 10 to preheat the engine coolant of an internal combustion engine, master power switch 110 and timer switch 112 are both closed to supply current through lead line 128 to the nichrome , ~,, .

103~i924 wire electrical resistance hea~ing element 4~. Heat-ing ele~.ent l~6 preheats at least portions of the cata-lytic agent of heater assembly 14 to an operati.ng tem-perature w~iich would produce a catalytic heat reaction with fuel discharged into the heater assembly. Timer switch 112 controls the length Or tirne current is supplied to heating element 46 and turns the heating element crr arter sufficient time has elapsed for the catalytic agent to be heated to an operating tempera-ture. Temperature responsive switch 56 closes inresponse to the preheating of the catalytic agent to : its operating temperature to supply current through lead lines 60 and 58 to energize electric fuel purnp 84.
When fuel pump 84 is energized, it supplies gasoline under pressure to fuel injector 62. The gasoline ls metered into injector 62 by orifice 92, becomes vapor-ized as it passes upwardly through evaporator tube 66, and is discharged into the interior of ceramic tube 38.
Under the influence Or the catalytic agent Or the heater assembly, the vaporized fuel undergoes a catalytic re-action producing heat which warrns liquid coolant in .
heat exchanger 12. Heating of the liquid coolant in chamber 16 of heat exchanger 12 produces a thermosiphon action which causes warmer liquid to rlow out of the heat exchanger through outlet conduit 30 and into thecooling system Or the engine, and cooler liquid rrom the engine cooling system enters the bottom of the heat exchanger through inlet conduit 28. Th~s preheats ,_ 10369~4 the liquid coolant of the internal combustion engine, and hence, the engine itself which greatly facilitates starting of the engine in cold weather conditions.
FIG. 8 illustrates a modified catalytic heat-er 10' embodying this invention in which like numeral~
designate component parts which are the same as the corresponding component parts of catalytic heater 10.
~he catalytic heater assembly 14' of heater 10' has a pair of ceramic end caps 130 received on opposed ends of heater assembly 14' and is centered in heat ex-changer jacket 12 by discs 67' and 68. Thermostatic switch 56 is secured to the upper end cup 130 by a suit-able potting material, such as the Leepoxy Epoxy System No. 16-149 (Trademark) available from Leepoxy Plastics, Inc., of Fort Wayne, Indiana. Liquid hydrocarbon fuels, such as gasoline, are at least partially vaporized and discharged within catalytic heater assembly 14' by a fuel injector 132 which has an evaporator tube 134 with a fuel screen 135 and a union 136 at the upper end there-of. Evaporator tube 134 is fixed to disc 67' with the lower portion thereof extending coaxially into heater as-sembly 14' through apertures in upper end plate 40' and cup 130. To prevent high winds from extinguishing the catalytic reaction of fuel with heater element 14', a tu-bular shield 138 on the upper end of heat exchanger 12 ex-tends substantially above exhaust or outlet ports 36.
Shield 138 is received over the upper end of outer tube 20 of heat exchanger 12 and retained thereon by a band or hose . _ ~0369Z4 clamp 140. If deslred, tubular shield 138 could be simply an e~tcnsion of outer tube 20 Or heat exchan~er 12, To receive and vaporize any liquid ~uel dis-charged from fuel inJector 132, a secondary evaporator assembly 142 is coaxially received in the lcwer end Or heater assembly 14'. Evaporator assernbly 1~i2 has an evaporator tube 144 into ~Jhich droplets of ruel dis-char~ed from tube 134 are funneled by a flared upper end 146. Evaporator tube 14L~ is fixed to lower end cap 42 Or heater assembly 14', extends throu~h lower end cup 130, and is closed at the lower end thereor by a plug 148 received in a union 150 fixed thereto.
Catalytic heater 10' is supplied ~Jith a pres- , surized hydrocarbon fuel in gaseous or liqllid form, such as liquiried petroleum gas or gasoline. Gaseous fuels are supplied to catalytic heater 10' through secondary evaporator assembly 142 by connecting a suit-able conduit to union 150 thereof with the injector 132 being sealed by inserting plug 148 in union 136 thereof.
Liquid fuels are supplied to catalytic heater 10' through injector 132 by a suitable condult connected to - union 136 thereof and the lo~-er end of the secondary evaporator is sealed by inserting plug 148 in unicn 150 thereof.

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1()36'~Z4 As shown ln ~IG. J, when catalyt;lc heal~er 10' is installed in an aut,omotive vehicle, gasoline may be supplied under pressure to injector 132 by a separate electric fuel pwnp F3ll with an lnlet connected by llne 86 through tee 88 to fuel line 90 of the ve-hicle (not shown) between the gasoline tank and th fuel pump Or the internal combustion engine Or the ve-hicle. The outlet of pump 84 is connected to in~ector 132 through a line 154 and union 136. As indicated by arrow 100, catalytic heater lOt is mounted so that the longitudinal axis Or the heater assembly 14~ extends generally vertically with fuel inJector 132 at the upper end thereof. Catalytic heater 10l is connected - by hoses 102 and 104 to the cooling system Or the en-gine and mounted at a vertical height in relation tl,ere-to in the same manner as catalytic heat;er 10 to produce a thermosiphon action to circulate ccolant to the cata-lytic heater and the cooling system.
A control box 156 with an electronic circuit 158 shown schematically in FIG. 10 cycles catalytic heater 10~ and fuel pump 84. Power is supplied to a DC
power bus 160 of control circuit 158 from battery 120 through a fuse 162 and a master power switch 164 with an indicator light 166 connected by lead lines 168, 169 and 170.

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1036'9Z4 Circuit 158 has a preheat control section 172 which is responsive to application oL' battery po~Jer to bus 160 to apply po~er to heatlng element 46 for a pre-determined tirrle interval to preheat the catalyst of heater assembly 14'. Control section 172 comprises a comparator 174 having a reference input 1'76 connected through a resistor 178 to bus 160, and having a thresh-old input loO connected through a resistor 182 to bus 160 and throu~h a capacitor 184 to ground 186 of the vehicle I'rame. A latch 188 receives a first input 190 - from the output 192 of comparator 171i/ and a second in-put 194 from bus 160 directly. Latch 188 has an output 196 connected through the anode-cathode junction Or a silicon diode 198 and thence through a coil 200 of a relay 202 to ground 186. A second diode 204 is con-nected in reverse polarity across coil 200 to suppress , inductive ringing in the coil when relay 202 turns off.
Relay 202 also has a pair of normally open contacts -~ 206, 208 connected to bus 160 and preheat element 46, and responsive to energization Or coil 200 to apply battery power directly to heating element 46.
In the operation of preheat control section ~ 172, the outpl~t of latch 188 is initially set to a high ; voltage state by application Or battery power to bus 160. This relatively high voltage forward biases diode 198 so that relay 202 is energized and preheat current is supplied to element 46. At the same time current flows through resistor 182 and into capacitor 184 so .

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103~i9Z4 that a charrje is graduall~ built Up t~lel'eupon. Arter an interval of time determined by thr values of resistor 1O2 and ca~,~citor 184, the voltage on the capacitor at threshold illpUt 1~0 Or cor~,arator 174 exceed~ the rerer-ence voltage at input 176 so that the cornparator pro-vides a reset signal at input 190 Or latch 188. The latch is thus reset so that the output thereor goes lo~r and rela~ 202 is de-ener~ized untll Inaster ~witch 164 is turned off and then on again to re;et latch 188 to a high voltage state. The prcheat time interval determined by resistor 182 and capacitor 184 is prererably in the range Or t~relve to fourteen minutes.
Control circuit 158 further comprises a purnp control section 210 which includes a first comparator 15 212 having its reference input 2~4 conrlected through a i resistor 216 to bus 160, and throu~h series connected resistors 218, 220 to ground 186 Or the vehicle frame.
A filter capacitor 230 is connected across resistor 22~.
The threshold input 232 of corlparatcr 212 is connected 20 through series connected resistors 234, 236 to bus 160, - and through a capacitor 238 to grourld 186. A second comparator 240 has its threshold input 242 connected to threshold input 232 of comparator 212, and has its reference input 244 connected to the junction of resis-25 tors 218, 220 Resistors 216, 218 and 220 thus forl~ a voltage divider which places a first reference voltage at reference input 214 of corrlparatcr 212, and a seconcl lower reference voltage at the reference inl)ut 244 Or _.

~03ti92~
comparator 24~. A resistor 222 an-l a nor;nally open pushbutton s~litch 228 are connected in series across resistor 236. Switch 228 is mounted on control box 156 and may be m3nually activated to prilnc pump 8/~ as ex-plained in detail hereinafter.
A latch 246 has a first input 248 connected to the output 250 Or comparator 212, and has a second in-put 252 connected to ~he output 254 of comparator 240.
The output 256 of l~tch 246 is connected throu~h a re-sistor 258 to the base Or a PNP transistor 260 which has its emitter connected to bus 160 and its collector connected through the solenoid coil 126 Or pump 84 to ground 186. A diode 262 is connected in reverse po-larity across coil 126 to suppress inductive ringing in the coil when transistor 260 turns off. Output 256 Or latch 246 is also connected through a resistor 272 to input 176 of comparator 174, and to a first input 264 of a discharge switch 266 which has a second input 268 con-nected to the junction of resistors 234, 236 and an out-put 270 connected to ground 186.
., In the operation of pump control section 210, output 256 of latch 246 is set high when battery - power is initially applied to bus 160 so that the emit-ter-base junction of transistor 260 is reverse biased and current is blocked from coil 126 of pump 84. In the meantime current passes through resistors 236, 234 into capacitor 238 so that the voltage at threshold input 232 Or comparator 212 gradually rises. ~Ihen this . .

~' risin~ voltage exceeds the rererence volta~e supplied at input 214 by voltage divlder 216, 218, 220, com-parator 212 supplies a reset lnput to latch 246 so that output 256 goes low, transistor 260 collducts and cur-:i .
rent is supplied to coil 126 Gf pump 84. At the same time, input 264 Or dlscharge~switch 266 goes low so that switch 266 discharges capacitor 238 through re-sistor 234 and discharge s~litch lnput 2~8 to ground 186.
When the decreasing voltage on capacitor 238 at thresh-old input 242 Or comparator 240 drops below the level of the second lower reference voltage supplied at refer-ence input 244 by volta~e divider 216, 218, 220, com-parator 240 provides a set signal at input 252 of latch 246 so that the output thereof goes high thus turning : 15 off transistor 260 and blocking current flow to coll 126 ,,.
: Or pump 84. Discharge switch 266 is also turned off at ~i this tlme so that capacitor 238 may rechar~e. Thus, 1'" -t pump control circuit 210 operates as an oscillator which ~ -~::, has a period and duty cycle dependent upon the relative ~............................................................................ .
~ 20 values of resistors 216, 218, 220, 234, 236 and capacitor , ~;
`~ 238. In the preferred.embodiment Or catalytic heater 10' :
the charge time of capacitor 238 through resistors 236 234 may be in the range of 5 to 15 seconds and preferably is about 10 seconds while the discharge time thereof ~- 25 through resistor 234 and switch 266 may be in the range ~ Or 30 to 80 milliseconds and preferably is about 50 to 60 .~ milliseconds. Thus, current is supplled to coil 126 of pump 84 preferably for 50 to 60 milliseconds at lO-second intervals.

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1~3~Y~Z4 To prime fuel pump 8l~ a swl~ch 22~ is closed to place resistor 222 in parallel with resistcr 236, thereby decreaslng the char~e tiMe for capacitor 238 and increasin~
the rate at ~;hich pun~p ~4 is cyc],ed. 'r~)e ~3ecreased charge time for capaeitor 238 when control section 210 is oper-ating ln the pump-priming rnode may be in the ran~e of 200 - to 700 milliseconds and is preferably about 400 to 500 n~lliseeonds~
Control eircult 158 also lnclvdes a pump in-hibit circuit 274 which is responsive to the tempera-ture of catalytic heater assembly l4 l to selectively inhibit activation of pump eontrol seetion 210 if heater deviee 10~ is not functioning properly. Circuit 274 includes a first NPN transi.stor 276 whieh has its base conneeted through a resistor 278 to the cathode of diode 198, and its emitter connected di.rectly to ground 186.
The eollector of transistor 276 is connected through a ,. resistor 280 to bus 160, and to the base of a second .. NPN transi.stor 282. The base of transistcr 282 is also 20 connected to grGund 186 through normally open thermal switch 56 whieh is mounted on heater assembly 14l and ; responsi.ve to the temperature thereof to eonneet the base of transi,stor 282 direetly to ~round. The emit-ter of transistor 282 is connected to ground and the . 25 colleetor thereof is connected to the junetion cf re-resistor 234 and capaeitor 238. Thus, when lateh 188 supplies preheat current to element 46, transi.stor 276 is turned on and transistor 282 is turned off so that capacitor 238 is allowed to alternately charge and 3_ , . , discharge as described above. If heater 10' is oper-atin~ properly, catalytic heater a3sembly 14' will be preheated to a temperature at whlch thermal swltch 56 closes an~ the base of translstor ~8'~ is connected to ground independently of preheat sect,ion 172 before the preheat section 1~2 turns of r. Ho~rever, ir the tempera-ture of heater asserr,bly 14l is below the temperature at which switch 56 closes when preheat section 172 turns off, or 1~' the heater asserllbly ternperature should there-after fall belo~r such predetermlned temperature, switch56 will open and current will be supplied to the base-emitter ~unction of transist,or 282 through resistor 2~0.
Transistor 282 will then be turned on to draln substan-tially all of the charge from capacltor 23~, and to thereby inhibit further operation of pump control sec-tion 210 and hence pump 84.
In using catalytic heater 10' to preheat the engine coolant of an internal combustion engine, master switch 162 is manually actuated to energize control circuit 158 to supply current to resistance heating element 46. Heating element 46 preheats at 3east por-tions of the catalytic agent of heater assembly 14' to an operating temperature which would produce a catalytic ~ heat reaction with fuel discharged into the heater assem-- 25 bly. The preheat control section 172 of circuit 158 controls the length of time current is supplied to heat-ing element 46 and turns the heating e3ement off after sufficient time has elapsed for at lea~t portions of the '., ~, , "
, ,, , ~'.' ' , , 103~9Z4 catalytic a~ent to be heated t;o an opcr~tin~ tempera-ture. Prior to the heatin~ element bein~; turned off by contr~,] section 172, ruel pump 8l~ i~. ener~lzed to discharge fuel throuh injector 132 into heatirlg ele-ment 14' by the pump control section 2].0 o~ controlcircuit 158 and, if catalytic heater 10' is function-ing proper].y, temperature responsive s~ri.tch 56 closes to assure continued cyclin~ of p-mlp 8l~ to supply fuel ; to the catalytic heater. The cyclic or pulsating flow Or liquid fue]. supplied by pump 84 to in~ector 132 is srnoothed or evened out by fuel screen 135, at least partially vaporized by evaporator tube 134 and dis-charged therefrom into heater assembly 14~ The vapor-ized portion of the fuel under the influence of the catalytic agent of heater assembly 14' undergoes a cata-lytic reaction producing heat ~Jhich warms 1 iquid cool-i,.
ant in heat excharlger 12. If the fuel is not coD~pletely vaporized by evaporator tube 134, the liquid portion ,'.; thereof will drop by gravity into secondary evaporator assembly 142 from which it ~Jill be subsequently vapor--~ ized and discharged into the interior of heater assem-~: bly 14' to undergo a catalytic reaction producin~ heat : to warm the liquid coolant in heat exchanger 12. Liquid . ~ fuel is vaporized in secondary evaporator assembly 142 because evaporator tube 144 is rnaintained at an elevated temperature by the heat produced by the catalytic reac-tion. Heatin~ of the liquid coolant in heat exchanger 12 produces a thermosiphon action to circulate the ,~

liquid coolant Or the engine and thus preheat the en-gine in the same manner as catalytic heater 10, The useful life Or the catalytlc agent Or the catalytic heaters is believed to be substantially de-creased by contact Or the catalytlc agent wlth liquid fuel, and hence, no fuel should be supplied to the cata- ~ -lytic heaters when they are not being operated. How-ever, it has been discovered that the main fuel pump Or at least some internal combustion engines creates suf~icient pressure surges or pulses in fuel line 90 to force ruel through conventional electric ruel pumps utilized with the catalytic heaters and thence into the catalytic heaters when they are not operating, thereby decreasing the useful life o~` the catalytic agent there-:
`~ 15 of. This may be prevented from happening by using con-ventional valves with a conventional electric pump sup-plying fuel to the catalytic heaters by arranging the valves to prevent fuel from flowlng through the conven-:-tional pump when the catalytic heater is not operating.

However, it is preferred to use a specially designed - pump, such as pump 84, with a suitable valve arrange- ;

ment incorporated directly therein.
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As shown in FIG. 11, pump 84 has a houslng 290 with a flexible diaphragm 292 received therein and 25 underlying a pump chamber 294 ln a carrier plate 296 - fixed ln the housing. Gasoline is admitted to pump `

- chamber 294 through inlet conduit 298, inlet valve i assembly 300, and passageway 302 through carrler plate ,. .

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2~f~ ar~ rc,c~ c~lc~ r~ Uj,h c~utlet pas~age~Ja~ 30!~ in carrier plat;e ~9~ cllt]et valve assem-bly 30~ and outlet conc3ult; 30~3 The glsoli~e ls rnoved through pu~ cl~amber 291~ by the I]exing of diaphral~
292 ~Jhich is act~Jated b~ an arJr,ature 3~0 cc,nnectèd there-to, yieldably biased in one directi(,~ y a sprirl~ 312, and Moved in the opposite directiGn hy energization of solenoid ccil 126. The length of the str-,lce of arrrl31ure 310 and hence the quantlly Or fuel de~lveI~ed on each dischar~e strolce Or pump 8ll is contllolled by a~justment of a threaded stop screw 314 received in a nut 316 fixed to housing 290.
Gasoline is prevented from flcwirlg through pump 84 when solerloid ec~il 126 is de-erlel~lze~ by a valve assembly ,18 mounted on carrier p]ate 296 and shown in FIG. 11 in the open position with coil 126 energized. Valve assemb]y 318 has a valve 320 with a bulbous stem 322 received for reciprocation in a counter-bore 324 in earrier plate 296 to elose and Gpen ( as sho~m in FIG. 11) fuel ol~tlet passage 304. Valve 318 has a metallie wear eap 326 on the lo~ler surfaee there-of and is yieldab]y biased by a spring 328 into en~age-ment with armature 310 for reeiproeation therewith.
In operation of pump 84 energizatiGn of eoil 126 moves armature 310 to the position sho~1n ln FIG. 11, thereby opening valve 316 and flexing diaphragm 292 to pull gasoline into pump chamber 291l through inlet con-duit 298, inlet valve 300 and passageway 302. ~Jhen --1 C~--1~3~9Z4 coi] 12~ is de-ener~iz~J, sE)r:lrl~ 312 m~vc.r. armature 310 upwardly from the posltion sh(,iln in FI~. ]1, thereby movin~; diaphral~rn 2~2 to dischar~e ~'uel f r~oM pt.ll,~p cl-an;-ber 294 thr~u~l passa~e;/ay ,oll~ outlet valve 30~ and outlet conduit 308, and, uporl cornp],etiorl oi' the dlschar~e stroke of diaphra~m 292, closin~ valve 320 a~ainst the bias of sprin~ 324. Thus, valve 3'20 r~rnains closed so lon~ as coil 126 is de-ener~ized, thereby pr~verltin~
gasoline from being forced throu~h pump 84 wherl tlle pw~
is not Gperatin~ by pressure surges or pulses in the fuel line gO to ~Jhich inlet. conduit 298 is connected.
Since the useful life Or the catal~tic a~ent is decreased by contact with liquid fuel, the quantlty of liquid fuel supplied to catalytic heaters 10 and 10' durin~ operation thereof should be controlled within close tolerances to assure that an excess quantity of ~: liquid fuel i,s not supplied to the catalytic heaters, .: The quantity of liquid fuel suppli.ed to heater 10 is controlled by adjustment of stop screw 31l~ cf pwnp 84 ,~ 20 and metering orifice 92 and the quantity of liquid fuel supplied to catalytic heater ]0~ is controlled by ad-justment of stop scre~r 314 of pump 84 and the rate of cyclin~ of fuel pump 84 by pump c,ontrol section 210 of control circuit 158. Preferably, catalytic heater 10', rather than heater 10~ is used with liquid fuels since the secondary evaporator assembly thereor prevents li-quid fuel from comin~ in contact with t;he catalytic a~cnt.

, , . , -2()-, , ~ heater ass(-n~ly eri~)odyLng t;hl~ inventlon ln which va~orized lue] is discharged into a closed elon-gate porous chalrl~)er extendln~ genera]]y vertJcally with a catalytic agent ~istrl~)uted ahout the o~ter periphery thereof provides a flanleless catalytic heater for an internal combustion engirle which ~ill operate sarely and efficiently, has a long service life and re~uires little or no maintenance. The use~ul lif`e of the cata-lytic agent o~ the heater device is prolonged when used with liquid luels by an evaporator received in the lower end of the closed chamber with the fuel injector over-lying the evaporator The arrangement Or an elongate catalytic heater assembly wi.thln a cylin~rical heat exchanger provides a compact heater device embodying this invention. The releasable mounting Or the heater assembly wil;hlr, an elon~ate tube which ls a ~rall of the heat exchanger provides a catalytic heater of economical manuracture and assembly and racilitates removal of the heater assembly for inspection, repair, or replacement after the catalytic heater has been instal]ed for use with an interrlal combustion engine.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:

1.
A flameless heater using a combustible hydro-carbon fuel for preheating liquid coolant of an internal combustion engine comprising; an elongate, cylindrically shaped heat exchanger having an inlet and an outlet for liquid coolant of an engine, said heat exchanger being adapted to be mounted with its axis extending generally vertically, an elongate catalytic heater assembly re-ceived in said cylindrically shaped heat exchanger, said catalytic heater assembly comprising an elongate porous tube end caps closing both ends of said porous tube and being impregnated with a catalytic material, an electric resistance heater element carried by said porous tube for preheating said catalytic material, and a fuel injector extending into said porous tube for dis-charging at least partially vaporized hydrocarbon fuel into the interior of said porous tube, whereby when a vaporized hydrocarbon fuel is discharged by said injector into said catalytic heater assembly when preheated by said electric resistance element, the fuel is oxidized by a flameless catalytic reaction to heat liquid cool-ant of the engine in the heat exchanger.

2.
The flameless heater of claim 1 which also comprises a temperature responsive switch mounted on one of said end caps.

3.
The flameless heater of claim 1 wherein said injector extends through one of said end caps and com-prises an evaporator tube adapted to discharge at least partially vaporized hydrocarbon fuel into the interior of said tube adjacent the mid portion of the longitude of said porous tube.

4.
The flameless heater of claim 2 wherein said injector extends through one of said end caps and com-prises an evaporator tube adapted to discharge at least partially vaporized hydrocarbon fuel into the interior of said porous tube adjacent the mid portion of the longitude of said porous tube.

5.
The flameless heater of claim 1 which com-prises an elongate metallic tube having an axial length exceeding the axial length of said porous tube of said heater assembly and an inside diameter exceeding the outside diameter of said heater assembly, locators re-ceived in said metallic tube adjacent opposed ends of said heater assembly to position said heater assembly generally coaxially within said metallic tube.

6.
The flameless heater of claim 5 wherein said metallic tube is a wall of said heat exchanger which is in contact with liquid coolant in said heat exchanger.

7.
The flameless heater of claim 5 wherein said locators comprise discs and which also comprises abut-ments on said metallic tube engageable with one of said discs to limit movement of said one disc generally axially through said metallic tube in at least one di-rection, said one disc bearing on said heater assembly adjacent one end thereof, and a spring interposed be-tween said other disc and said heater assembly to urge said one disc into engagement with both said abutment and said heater assembly.

8.
The flameless heater of claim 5 wherein at least one of said locators is releasably retained in said metallic tube to releasably retain said heater assembly therein.

9.
The flameless heater of claim 5 wherein said metallic tube has circumferentially spaced re-entrant slots in one end thereof and at least one of said lo-cators has tabs thereon engageable in said re-entrant slots to releasably retain said one locator and said heater assembly in said metallic tube.

10.
The flameless heater of claim 7 wherein said metallic tube has circumferentially spaced re-entrant slots in one end thereof and said other disc has tabs thereon engageable in said re-entrant slots to releasably retain said other disc and said heater assembly in said metallic tube.

11.
The flameless heater of claim 5 wherein at least one of said locators comprises a disc releasably receive in said metallic tube to releasably retain said heater assembly therein.

12.
The flameless heater of claim 5 wherein said metallic tube communicates with the atmosphere adjacent both ends of said porous tube of said heater assembly whereby atmospheric air may pass upwardly through said metallic tube adjacent the outer peripheral surface of said heater assembly.

13.
The flameless heater of claim 1 wherein said injector comprises a tube extending into said porous tube adjacent the lower end thereof.

14.
The flameless heater of claim 1 wherein said injector comprises a first metallic tube adjacent one end of said porous tube and the flameless heater also comprises a second metallic tube closed adjacent one end and at least in part received in said porous tube adjacent the other end thereof, said first and second tubes each having an open end within said porous tube with said open ends being in spaced-apart generally opposed and generally coaxial relation to each other.

15.
The flameless heater of claim 1 wherein said injector is adjacent the upper end of said porous tube and the flameless heater also comprises an evaporator received in said porous tube adjacent the lower end thereof and underlying said injector to receive liquid fuel discharge from said injector and subsequently vaporize such liquid fuel and discharge the vaporized fuel into said porous tube.

16.
The flameless heater of claim 15 wherein said evaporator comprises a metallic tube with a closed lower end and a flared upper end adapted to funnel liquid fuel discharged from said injector into the interior of said metallic tube.

17.
A flameless heater using a combustible hydro-carbon fuel in liquid state for preheating liquid cool-ant of an internal combustion engine comprising; an elongate heat exchanger having an inlet and an outlet for liquid coolant of an engine, said heat exchanger being adapted to be mounted with its axis extending generally vertically, an elongate catalytic heater assem-bly received in said heat exchanger, said catalytic heater assembly comprising an elongate porous hollow tubular carrier impregnated with a catalytic material, both ends of said hollow tubular carrier being closed, an electric resistance heater element carried by said tubular carrier for preheating said catalytic material, a fuel injector at least in part received in said hollow tubular carrier adjacent the upper end thereof for dis-charging at least partially vaporized hydrocarbon fuel into the interior of said hollow tubular carrier, and a fuel evaporator at least in part received in said hol-low tubular carrier adjacent the lower end thereof and underlying said injector to receive liquid fuel dis-charged from said injector and subsequently vaporize such liquid fuel and discharge the vaporized fuel into said hollow tubular carrier, whereby when vaporized hydrocarbon fuel is discharged into said catalytic heater assembly when preheated by said electric resis-tance element, the fuel is oxidized by a flameless catalytic reaction to heat liquid coolant of the engine in the heat exchanger.

18.
The flameless heater of claim 17 wherein said hollow tubular carrier comprises an elongate rigid porous tube, end caps closing both ends of said porous tube, and a fibrous material overlying said porous tube and impreg-nated with said catalytic material.

19.
The flameless heater of claim 17 wherein said fuel injector and said fuel evaporator each comprise a metallic tube extending at least in part into said hol-low tubular carrier in generally coaxial alignment with each other and each having an open end with said open ends being in spaced-apart generally opposed relation within said tubular carrier.

20.
The flameless heater of claim 17 wherein said heat exchanger has a generally cylindrically shaped metallic tubular wall having an axial length exceeding the axial length of said hollow tubular carrier and an inside diameter exceeding the outside diameter of said hollow tubular carrier, said metallic tubular wall of said heat exchanger being in contact with liquid cool-and in said heat exchanger and lying adjacent to said catalytic heater assembly, and locators carried by said metallic tubular wall of said heat exchanger adja-cent opposed ends of said catalytic heater assembly to position said catalytic heater assembly generally co-axially within said metallic tubular wall of said heat exchanger.

21.
The flameless heater of claim 17 wherein said evaporator comprises a metallic tube with a closed lower end adapted to receive liquid fuel discharged from said injector into the interior of said metallic tube of said evaporator.

22.
A flameless heater using a combustible hydro-carbon fuel for preheating liquid coolant of an inter-nal combustion engine comprising; an elongate heat exchanger having an inlet and an outlet for liquid cool-ant of an engine, said heat exchanger being adapted to be mounted with its axis extending generally vertically, an elongate catalytic heater assembly received in said heat exchanger, said catalytic heater assembly comprising an elongate porous hollow tubular carrier impregnated with a catalytic material, both ends of said hollow tu-bular carrier being closed, an electric resistance heater element carried by said tubular carrier for pre-heating said catalytic material, a first fuel injector tube at least in part received within said tubular carrier adjacent one end thereof for discharging at least partially vaporized hydrocarbon fuel into the interior of said hollow carrier, and a second tube sealed adjacent one end and at least in part received within said tubular carrier adjacent the other end thereof, said first and second tubes each having an opening with in said tubular carrier and being at least in part generally coaxially aligned with said openings in spaced-apart generally opposed relation to each other, where by when a vaporized hydrocarbon fuel is discharged by said injector into said catalytic heater assembly when preheated by said electric resistance element, the fuel is oxidized by a flameless catalytic reaction to heat liquid coolant of the engine in the heat exchanger.