US2131635A - Steam heater for automobiles - Google Patents

Description

Sept. 27, 1938.

R. F. MULLEN STEAM HEATER FOR AUTOMOBILES Filed March 7, 1934 2 Sheets-Sheet l Sept. 27, 1938. R, F. MULLEN STEAM HEATER FOR AUTOMOBILES Fiied March 7, 1934 2 Sheets-Sheet 2 dwang@ Patented Sept. 27, 1938 Raymond F. Mullen, Rochester, N. Y., assignor Motors Corporation, Rochester,

to General N. Y., a corporation of Delaware.

Application March '2, i934, serial No. '114,365

3 claims. X (C1. 2st-12.3)

This invention relates generally to an improved heating system for motor vehicles in which the waste heat from the exhaust gases of the internal combustion engine is utilized to generate steam which is supplied to o ne or more radiators in the vehicle from which heat is dissipated and the steam condensed by heat radiation and the condensate returned to the steam generator.

One object of this invention is to provide a simple control which will automatically regulate the quantity of steam generated by automatically varying the amount of liquid available at the steam generator so as to maintain a fairly constant pressure irrespective of changes in exhaust gas temperature which may vary from 350 F. at low car speeds to 1400 at higher car speeds.

A further object is to provide this pressure control in a system which is alwaysl completely closed so that there can be no lossof vapor or liquid from the system except for leaks which may develop by reason of loose or faulty connections, and a convenient means is provided to supply only the exact amount of liquid required for proper operation at the time of installation or to rell the system whenever required by reason of leakage.

A still further object is to so design the system as to provide for the return of substantially all liquid to the steam generator when the heating system is not in use where this liquid may freeze l without injury to the system with the connecting lines between this steam generator and radiator so constructed and arranged as to facilitate and cause the proper circulation whenever the system may be again operated, or in other words,.imme diately upon starting the engine which furnishes its exhaust heat to the steam generator.

Many novel features of this invention, such as, for instance, the radiator construction and the other detailsof the various parts which have been found to be of particular advantage in the system will appear from the following detailed description of the structure and operation of the system which is illustrated by way of example in the accompanying drawings, in which:

Fig. 1 is a side elevation with parts in section of the entire system as applied to an automotive `vehicle.

Fig. 2 is an enlarged fragmentary front view with parts in section viewed in the direction of the line 2-2 of Fig. 1.

Fig. 3 is an enlarged front elevation, partly in section, of the radiator appearing in Fig. 1'.A

Fig. 4 is a rear elevation of the radiator shown in Fig. 3.

-various functions of these parts and the opera-f Figs.`5 and 6 are detailed views taken respectively, on line 5- 5 and line 6--6 of Fig. 3.

Fig. 'I is a front elevation, partly in section, of a modified form of radiator.

Fig. v8 is a rear elevation of the radiator shown 5 in Fig. 7. v

Fig. 9 is a bottom view, partly in secti n,ltakenv on line 9-9 of Fig.'l.

Referring first to Fig. 1, there has been shown diagrammatically only dthose parts of the usual 10 automotive vehicle which are essential for an understanding of the application of the present heating system. The internal combustion vengine is indicated generally at I in the engine compartment which is separated from the body compartment in the usual manner by the dash 2 and floor boards 3. This engine includes the usual exhaust manifold 4 and exhaust pipe 5 and is preferably provided with the usual cooling radiator and fan (not shown) and in this and other respects may be generally similar to standard practice.

The principal parts of the heating system shown in Fig. 1 consist of a steam generator o r boiler unit indicated generally at 6, a heater unit indicated generally at 1, and a-pressure control 25.

unit indicated generally at 8'. The detailsof these parts and the connections therebetween will next be described and followed by adescription of the tion of the entire system.

The boiler unit 6 which lsfmore fully described and claimed in a copending application, S. N. 714,366, led March', 1934, now Patent No. 2,048,882, granted July 28,-1936, consists primarily of a. casing 9 which'is preferably inter- 35 posed in a horizontal portion of the exhaust pipe `5, and a coiled tube rlll withinv the casing v$1 in the path of the exhaust gases. 'I'he casing 9 may be readily installed in the usual exhaust pipe by cutting and removing a portion thereof 40 of slightly greater length than the casing, sliding the 'clamping collars Il over the ends of the adjacent exhaust pipe sections, then placing the casing between these sections and securing the collars to the end walls of the casing (which have central openingsfor passage of exhaust gases from one exhaust pipey section to the other) by means such as bolts l2, and finally tightening the split sleeve portions of the collars around the exhaust pipe sections by the contractible bands i3 fitted on these split sleeve portions. A support I4 for the exhaust pipe is preferably located at a point near the boiler.

It should be noted that the diameter of the boiler casing 9 is somewhat greater than that 55 of the exhaust pipe so that the boiler tube I0 does not cause excessive back pressure ir the exhaust line, and ,that the tube I0 is preferably formed into a double coil to provide a large surface contact with the `exhaust gases. 'I'he ends of the tube Ill, are extended through one end wall of the casing 9 to provide terminals for the connection 'of the steam supply conduit section I5 and condensate return conduit section I6 which extend to the radiator of the heaterunit 1.

be apparent from Fig. 1, the steam supply conduit is of greater diameter than the condensate return conduit and these conduits extend upwardly and are jointed together between, the boiler and radiator terminals by a tube I1 in communication with both conduits. The conduit section I5 extends almost to the upper end of this tube as indicated by dotted lines at I8, whereas the conduit section lliV opens into this tube at its extreme' lower end for a purpose which will be set forth hereinafter. From the upper end of the connecting tube I1, the steam supply conduit section I5 and the condensate return conduit section I6 extend upwardly and through a single opening I9 in the dash 2 for connection to the radiator terminala The heater unit I is shown as mounted on the dash 2within the body compartment and consists ,generally of a finned radiator 20 for the heating medium with an electric motor 2| driving fan 22 for creating a forced circulation of air through the nned radiator. Theradiator 20 is provided with threaded bosses 23 on its rear side towards the fan to. receive mounting bolts 24 with spacing sleeves 25, and the motor and fan may be secured to the radiator as a unit by the grille 26. l

".Iiie radiator 20 is further provided with a casing `2'I on which is secured a deflector 'assembly at the front ofv the radiator which includes an -pressures'de`veloped -in the system so that it is upper shroud portion 28, peripheral outlets such as 29, and an .adjustable deector portion 30 pivoted horizontally to the lower` ,edge of the shroud portion. 'I'he connection of the deflector assembly to the radiator casing is preferably such as to permit 'an initial mounting at different circumferential positionsso that more heated air may be directed diagonally to one side than the other if desired by reason of locating the heater unit to either side of the centerof the dash. A wire mesh guard 3| may be placed directly behind the adjustable deilector portion 30, and a sheet metal guard 32 provided to shield the connections of the conduits I5 and I6' to the radiator 20.

The -radiator 20 has been specifically designed tosafely withstand the maximum steam pres-A suresl developed in the heating'system and pro-G vide a large radiating surface and air passages to insure an eflicientheat transfer with forced air circulation. Referring more particularly to Figs. 3 to 6, inclusive, the radiator 2l) comprises a single, substantially triangular,- vertical duct or liner 33 which is surrounded for the greater portion of its length by a cast body 34 formed with' Aparallel radiating flns 35 vextending horizontally from opposite sides and of varying length to outline the circular periphery of theradiator. The cast body 34 is preferably an aluminum silicon alloy which has-high heat absorbing and con- -ducting properties but a fairly low dissipation whennot in 'a forced draft. Such an alloy is, however,slightly porous at the temperatures and not suitable-as a duct for the heating medium which is constituted by the liner 33 preferably of copper which oifers'slight` resistance to/heat passage if in close contact with the heat radiating body 34.

` Although the aluminum body and fins might be die cast and the copper duct or liner press fitfront of th radiator with side walls 31 converging to the rounded apex at the rearv side-of the radiator. By reason of this decrease in crosssection from one side of the radiator to the other, it is possible to cast the body and fins about the duct or liner with a single mold which may be withdrawn in one direction fromL the rear of the radiator, and to further facilitate the withdrawal of the mold it will be noted from Fig. 5 that each of the radiating ns 35 decreases in thickness towards the rear` of the radiator.

By'virtue of the substantially triangular duct or liner 33 and the varying cross section of the radiating fins which might be said to taper rearwardly or towards the fan 22, the air passages around the body 34 and between the radiating fins 35 decrease in size towards the front or outlet side of the radiator lso as to set up a resistance to the free passage of air and increase the heat transfer by insuring good contact with the radiating surfaces. The walls 36 and '31' of the duct or vliner 33 are slightly bulged outwardly and all i corners rounded to insure a perfect bond with the cast body since it was found that if these walls were straight and the corners too abrupt there would be a tendency for the walls of the liner to collapse to some extent and draw away from the body during the casting operation.

'I'he modified form of radiator 38 shown in Figs.4 7 to 9; inclusive, differs principally from that` above described in the provision of a copper duct or liner 39 which is substantially oval, and may be conveniently formed by half sections with the curved abutting ends at the top and bottom united by silver soldering. Except for portions of this duct or liner which are exposed at the top and bottomjwith openings 40 and 4I for conduit connections, the same is enclosed by the aluminum body 42 provided with radiating. ns 43A which may be cast directly on the duct or liner.

It will be noted that this Aduct or liner 39 is substantially triangular in cross section vand the radiating fins 43 also decrease in cross section towards the rear side of the radiator 38 to facilitate the casting operation and obtain an efficient -heat transfer as has been heretofore described with reference to the radiator 20 to Figs. 3 to 6, inclusive.7

Referring again to the showing in Fig. 1, the

lower end of the radiator duct or liner 33 receives the cap or cover 44 which'is preferably secured thereto by silver solder. This cap 44 is provided with screw threaded terminals for the connection of the conduit sections I5 and I6 with pas,- sages which place these conduits in communica# tion with the interior of the radiator. For a purpose which will be noted hereinafter, the cap 44 has 'an upward extension 45 within the radi- :2,1's1,escz ator about the passage which communicates with extends through this opening and is secured therein by means such as silver solder. This conduit 46 is extended intothe radiator so as to communicate therewith adjacent the extreme upper end of the radiator, and extends downwardly within the radiator casing, then rearwardly through the opening I9 in the dash and upwardly Within the engine compartment to a terminal connection with the control unit 8.

The control unit 8 is supported on the dash withinthe engine compartment above the horizontal plane of the radiator 2U by means such as the bracket 41 carried by the heater mounting bolts 24, and includes a closed control chamber 48 with radiating ns 49. The chamber 48 is provided at its bottom with a fittingv 56 having a screw threaded lower end for the terminal connection to the conduit 46 with a vertical passage to place this conduit in communicatlon--with the interior of the chamber. The fitting 50'is also formed with a lateral passage which leads from the vertical passage to an outlet which is normally'closed by the fuse plug 5l secured over this outlet by the threaded sleeve or .hollow nut 52.

Referring to Fig. 2, the bracket 41 also serves as a support for a ller assembly 53 which includes a casing with aseparate chamber 54 of predetermined volume with a removable cover 55. A fitting 56 at the bottom of the casing is provided with a hollow upward extension 51 secured to the bottom of the chamber 54 and with a screw threaded terminal which is ad-apted to receive either the plug nut 58 orhave the conduit 46 secured thereto after removing this plug ik l nut to place the chamber 54 and the passage through the fitting 56 in communication with the heating system.

Withreference to the operation of the heating system above described, it is desired to first. note that distilled water has been found to be the most satisfactory heating medium in av system which is entirely closed to the atmosphere since apparently the standard anti-freeze solutions are subject to decomposition at high temperatures, and in some instances, generate a fixed gas which is not completely absorbed and produces a cumulative rise in pressure which cannot be readily controlled. Since water is subject to freezing thesystem has been so designed as to operate with -only a small amount of this heating medium and the installation of the system is suchthat this water will drain back to the boiler when the engine is not in operation where it may freeze and expand without injury to the system and be available to be immediately thawed out and generate steam whenever the engine is started.` Y

In a completely closed system Such as disclosed herein it will be apparentthat the opv eration as well as the pressure control of the system depends upon the relative volumes of vthe various parts and the amount of heating,

medium in the system so that sufficient liquid is available .to obtain satisfactory pressure and heat transfer at low engine speeds and exhaust temperatures, and the proper amount of this liquid withdrawn from circulation or prevented from returning to the boiler at high engine speeds and exhaust temperatures to regulate the amount of liquid available for steam generation and prevent the generation of excessive pressures in the system.

The present system has been so proportioned as to use only about ounce of water and the automatic control functions to regulate the amount of liquid in effective circulation dependent upon the heat radiation from the radiator and the exhaust gas temperature at the boiler so as to normally maintain a predetermined pressure of approximately 150 lbs., which may be defined as the pressure control point of the system. At relatively low vcar vspeeds such a pressure is not immediately obtainedand with sud,

den increases in car speed the vpressure may exceed this momentarily, but with steady driving at any speeds above 25 or 30 miles an hour, the pressure is uniformly maintained at this controlpoint.

In normal operation, referring to Fig. 1, `When"the engine is started, the exhaust gases coming in contact with theboiler tube Ill quick- 1y heat theismall amount of` Water therein (first vthawing this water if frozen) and generate steam which passes through the steam supply conduit sections I5, and I' to the radiator 20 where it is 'condensed by heat radiation and the condensate returns to the boiler jthroughthe conduit sections I6'v and I6 which are of smaller cross section than the steam supply conduit sections to set up a resistance so as to maintain propercircul-ation at all times. If outside air temperatures are very low, there is a possibility that a small amount of liquid might be frozen in the small return conduit, and with extremely low temperatures the steam may be of suiciently low temperature when it reaches the radiator that the condensate may actually freeze in the small return conduit or in the bottom of the radiator and prevent any return of condensate tothe boiler andthe system would'become'inoperative. To obviate this possibility,'the conduits are connected together by the tube'I1 between the boiler and radiator so that an initial circulation may be set up between this tube and the boiler and the positive circulation of steam and condensate in the conduits established by the extension I8 of the conduit section I5 within the tube I1 so that any condensate therein will return to the boiler through the conduit section I6. Then, as the steam temperature and pressure and amount'of steam being generated increase suiiicientlyy to overcome the cooling action of the conduit sections I5' and I6 and radiator 20, a circulation will be setup through these conduits and the radiator, and the upward extension within the radiator will serve to admit steam to the radiator above thebottom of the radiator -and cause the condensate to return through the conduit section. Ilv to the tube I1 from which it is returned to thoner through the conduit section I6. It should be noted that the extension 45 also functions as an overow in the bottom of the radiator to prevent a sudden surge of condensate down the steam supply conduit section I5' during Vsudden or` momentary appreciable decrease in speed, andthe tube I1 functions at all times to separate the steam and condensate to insure positive circulation.

It will be obvious that with the exhaust temperatures which are available 'for steam generation, more steam will be generated on continued operation atnormal speeds 'or at relatively high speeds than can be condensed in the radiator 29 and to prevent excessive pressures being genv erated under such conditions, the automatic control has been provided to regulate the amount of liquid available for steam generation as has been mentioned hereabove, and which functions as follows:

As the steam generated in the boiler passes through the steam supply conduit and lls the radiator 2U, the air in these portions of the system is forced into the conduit 46 and into the control chamber 48. As the generation of steam continues, this air is compressed in the control chamber in advance of the steam which when it entersthe control chamber is condensed by reason of the radiating iins 49 and the location of this chamber in the engine compartment where it is cooled b-y air from the engine cooling fan.- The exact amount of steam which may enter and be condensed and retained within the control chamber will, of course, vary in. accordance with the changes in amount of condensation in the radiator 20 and exhaust gas temperatures. but the pressure in the system will never greatly exceed that for which it is designed, as has been heretofore noted, when the pressure of both the compressed air and liquid in the control chamber and the steam in the radiator will be at the so-called pressure control point, and the amount of liquid actuallyin circulation between the boiler and radiator will be only sucient to maintain this predetermined pressure in the entire system. Then it will be apparent that whenever the pressure in the radiator falls below this predetermined pressure by reason of an increase in the amount of condensation in the radiator or a decrease in exhaust .gas temperature, the higher air pressure above the liquid in the control chamber will force some of this liquid back to the radiator and increase the amount of liquid available for steam generation at the boiler.

With reference to the above description of the operation of the control chamber, it should be noted that the conduit 46 connecting this chamber with the upper end of the radiator is of relatively small cross section so as to keep the'air always in advance `of all vapor or condensate so that this air will be compressed to the proper extent and will function to return liquid to circulation in the manner set forth. The cross section of the conduit 46 is also of such size as to prevent any appreciable wall ow and therefore offer sucient resistance to the passage of liquid to prevent the sudden return of all liquid in the control chamber to the radiator on merely a momentary drop in pressure in the radiator.

As a safetyfeature, the fusible plug 5I is provided and is of such vmaterial as will melt at a temperature of about 400 F. and place -the system incommunication with the atmosphere if this temperature is ever attained and thereby relieve the excessive pressure by exhausting the heating medium in which event the fusible plug would naturally have to be replaced before adding heating medium to the system as will be presently described. It should be noted that the use of a pressure responsive safety plug is impractical in view of the small area of the plug which would be in communication with the system and on which even considerable changes of pressure would have substantiallyno eect.

It will be noted that no means has been provided to shut oifthe operation of the heating utes to expel or boil all water from the system after which the conduit may be replaced on the fitting.

It has been heretofore pointed out that a predetermined amount of water is a requisite to proper operation of the present heating system, and the filler chamber 54 with the passage in fitting 56 is of such size as to hold only this amount of water. Before adding water to the system at the time of installation or after repairing leaky connections or replacing the fuse plug, the conduit 46 should be disconnected from the control chamber fitting 5l) and the engine run for several minutes to boil off any water in the system. After shutting off the engine. and permitting the system to cool for about ten minutes, the plug nut 58 is removed and the conduit 46 connected to the terminal on the fitting 56.*` 'I'he cover 55 which prevents the accumulation of any dust or foreign matter in the filler chamber 54 may then be removed and the chamber filled with distilled water which will gradually run into the system through the restricted conduit 46. If the system isentirely cool, this should take from three to five minutes, and if not cool, drainage willv occur more readily if the connection of the steam supply conduit section l5 to the radiator bottom cap 44 isloosened` to relieve air pressure in the system. After filling, it is apparent that the conduit 46 should be transferred back to the` Instead of extending the conduit 46 downwardly' within the radiator casing and through the open'- ing I9 in the dash, it will be obvious thatfaffur-y ther opening may beprovided in the dash just y below the control unit 8 for the conduitf46 which could then be connected to the upper end of` the:

radiator and extend through this further operiing for connection to the control chamber 48 or ller chamber 54 without extending below the,4

connection to the radiator, thereby eliminating the liquid trap mentioned hereabove.

If desired, the system may be operated at pres'-` Y sures below those obtained by the relative volumes of the various parts and the predetermined amount of liquid for which the system may be designed as has been described hereabove,r by A disconnected from the control chamber luntil l i the desired amount of air has been expelled and then connecting this conduit to the control chamber and thereby closing the system to the atmosphere before any steam escapes from the system.

`Although the foregoing detailed description has related specifically to the construction and operation of the heating Isystem shown in the drawings, it will be understood that the invention :is not limited to this specific form but is susceptible of various modifications and alternative constructions which may fall withinthe spirit and scope of the invention as expressed in the appended claims.

I claim:

1. In a steam heating system for motor vehicles, apressure control and safety valve assembly mounted in the engine compartment and comprising a pressure control chamber adapted to normally prevent the generation of excessive pressure in said system, a tting on said chamber with `a terminal to provide for a detachable connection to the heating system to place the chamber in communication therewith, and an outlet in said fitting which is normally closed by a fusible plug.

2. In a steam heating system for motor vehicles, a pressure control and filler assembly including a supporting bracket adapted to be mounted in the engine compartment and comprising a pressure control chamber adapted to automatically regulate -the pressure in'said system and an adjacent lling vchamber mounted on said supporting bracket` and provided with terminals for the detachable connection of a conduit to place either of these chambers in communication with the system at will.

3. A steam heating system for motor vehicles comprising in combination with the vehicle engine and its exhaust pipe, a heating radiator in the body compartment of the vehicle mounted on RAYMOND F. MULLEN. 20

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