US3865098A

US3865098A - Heater for asphalt concrete roadways and the like

Info

Publication number: US3865098A
Application number: US369775A
Authority: US
Inventors: Earl F Cutler
Original assignee: CUTLER REPAVING ASS
Current assignee: CUTLER REPAVING ASS
Priority date: 1973-06-13
Filing date: 1973-06-13
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11
Also published as: CH575513A5; DE2428437A1; FR2233445B2; SE401536B; SE7315958L; FR2233445A2; IT1011434B; GB1428448A

Abstract

Disclosed herein is an embodiment of a heater for use in repaving asphalt concrete roadways, and the like. The heater utilizes fuel, such as pentane, to direct a flame into a radiant heating target element by means of a nozzle which changes the direction of the flame from a combustion chamber and a deflector to redirect and focus the flame onto the radiant heating target element. The flame is redirected radially outwardly along the radiant heating target element so that the flame will not impinge on the road surface, thereby providing substantially entirely radiant heat to heat the road surface. Such radiant heating burners will penetrate the road surface to a depth of one inch or more in a relatively short period of time whereupon the heated and softened asphalt together with portions thereof beneath the heated portions are excavated. Additional heat is applied to the excavated material to further soften it and small quantities of new aspahlt material may be added if desired before the reworked material is again laid to form a road surface.

Description

[ 1 Feb. 11, 1975 such as pentane, to direct a ame into a radiant heating target element by means of a nozzle which changes the direction of the flame g tary outg target element so that on the road surface,

y radiant heat to heating burners f one inch pon portions cavated.

{57] ABSTRACT Disclosed herein is an embodiment of a heater for use in repaving asphalt concrete roadways, and the like. The heater utilizes fuel from a combustion chamber and a deflector to redirect and focus the flame onto the radiant heatin get element. The flame is redirected radiall wardly along the radiant heatin the flame will not impinge thereby providing substantially entirel heat the road surface. Such radiant will penetrate the road surface to a depth 0 or more in a relatively short period of time whereu the heated and softened asphalt together with thereof beneath the heated portions are ex States Pae 1; i 1

HEATER FOR ASPHALT CONCRETE ROADWAYS AND THE LIKE Inventor: Earl F. Cutler, Lawrence, Kans.

Assignee: Cutter Repaving Associates,

Incorporated, Lawrence, Kans.

Filed: June 13, 1973 Appl. No.: 369,775

US. 126/2712 A, 431/329, 431/348 Int. Cl. F23c 5/00 Field of Search 126/2712 A; 431/171, 172, 431/329, 347, 348

References Cited UNITED STATES PATENTS Cutler 10 Claims, 6 Drawing Figures Additional heat is applied to the excavated material to further soften it and small quantities of new aspahlt material may be added if desired before the reworked material is again laid to form a road surface.

Vim v X AAXA wms gv nm w a fiewev i ill]. 1 S Q3377B7 U H QUMP H 2 N 66 6 0 v1 W mm .H W 2 l m m H1 mm H 1 mu ao m Hum e r WW W D e r 1 1 I r i l I 1 I, m Wm M m m 0e n N u H .F 0 mwflovmflfl m w mw n .me (V C U tm NWWQMWC h U 7-1 55673 rr 5 6666667 weo 9999999 m HHHHHHH mm 9482244 mderr 1 m E & 0907565 I. uo 7 024 yn 9 354 mflr 4 8923 2 n fls 00 ,12 nsHu 1 1 1 31 .33 DIAAB PATEHTED FEB 1 1 I975 SHEET 10F 2 OODOOOUlOOOOOO HEATER lFOR ASPHALT CONCRETE ROADWAYS AND THE LIKE BACKGROUND OF THE INVENTION,

This invention relates generally to roadway resurfacing apparatus, and more particularly to radiant heating units utilized at one or more work stations within the roadway resurfacing apparatus.

This invention deals with substantial improvements in my earlier filed copending application Ser. No. 282,005, filed Aug. 18, 1972, now US. Pat. No. 3,801,212, and the entire subject matter thereof is incorporated herein by reference to the extent necessary for a complete understanding of the present invention. Road surfacing apparatus, in general, as set forth in my US. Pat. No. 3,361,042, provides means for quickly and inexpensively resurfacing roadways made of asphalt concrete material and the like. The apparatus may be 8-12 feet wide and 4050 feet long and move along the roadway in a slow rate so that during a single continuous pass over the pavement the old road surface in front of the machine is excavated and converted to a refinished road surface at the rear of the machine. A distinct advantage of repaving apparatus of this type is that the finished repaved strip of roadway is substantially immediately available for vehicular traffic within a matter of minutes after completion.

The heater appartus of this invention is advantageously utilized in road repaving machinery which performs the following functions during the repaving process. First the road surface is heated in a non-oxidizing environment consisting substantially of all radiant heat so that the heat penetration through the asphalt surface is obtained to a depth of approximately 1 inch or so. This is substantially immediately followed by a scarfing operation which deeply excavates the heated asphalt material to disarrange the surface to a depth of at least the depth of heat penetration, and generally to a depth of one or two inches more. Then piling the arranged material for maximum surface exposure so that it can be further heated by either the same or second following heating apparatus, this heat being substantially entirely radiant heat also. If it is found necessary at this time to add a given amount of conventional tack coat or the like to help weld the total conglomeration of mixture to the substrate from which the heated material was removed such coating is then applied. This followed by a tamping operation and screening which, in turn, is followed by compacting as by conventional rollingmeans or the like.

The heater apparatus of this invention may also be used as an attachment to a tractor or other road vehicle especially where it is desired to heat relatively small areas of a roadway for patching or other minor repairs.

Heretofore, heating of the road surface was accomplished primarily by a flame heating apparatus which produced a non-oxidizing atmosphere within a heating chamber so that the temperature of the road surface would be elevated higher than the material could experience in the air without being set on fire. This was needed for maximum heat penetration of the road surface. However, to achieve this high temperature and penetration of heat, the amount of fuel required was substantial and in some cases oxidization would occur and the road surface would be set on fire. These inevitable disadvantages of utilizing open flame heating on asphalt road surfaces were among factors which slowed the progress of repaving road surfaces.

SUMMARY OF THE INVENTION Accordingly, it is a feature of this invention to provide a new and improved radiant heating apparatus for use in road repaving machines as described above wherein more efficient heat energy is delivered to the road surface so as to operate the heating apparatus with a lesser quantity of fuel.

Still another feature of the present invention is to provide heating apparatus for road repaving machinery which provides substantially entirely the infrared radiant heat to be directed to the road surface so as to raise the temperature of the road surface to about 300F and to a penetration depth of about l inch or more.

Another feature of the present invention is to provide a new and improved heating unit which has stable operating characteristics with regard to variations in atmospheric pressure within the heating chamber receiving the heating units, thereby minimizing the effects of blow-out as a result of lateral winds being subjected onto the radiant heating unit during operation.

Briefly, the heating apparatus of this invention may form two or more work stations ofa road repaving machine and each heating apparatus preferably is of substantially the same structural configuration. Furthermore, each of the heating apparatus include a plurality of radiant heating units mounted within the housing thereof, each of the units being of improved structural design with regard to the manner in which flame heat is reconverted to radiant heat. Therefore, only details of a single heating apparatus will be set forth particularly herein, and only the details of a single radiant heating unit utilized within the heating apparatus will be shown. It will be understood however, that all of the radiant heating units used in each ofthe radiant heating apparatus are substantially of the same structural configuration.

The radiant heating apparatus is provided with a fuel receiving manifold which is positioned over a heating chamber and is arranged to deliver relatively low pressure air fuel mixture to each one ofa plurality of combustion chambers associated with the radiant heating units. Each of the radiant heating units provides a discrete fuel burning combustion chamber to receive the air fuel mixture from the manifold. This air fuel mixture may be preheated in any one of a plurality of different suitable manners, for example, as set forth in my abovementioned earlier patent application. To achieve the proper pressure and flow of fuel and air mixture, a variable quantity air blower is in fluid communication with the manifold chamber so that delivery of air fuel mixture to the nozzle can be altered as desired.

By so controlling the air fuel mixture and the pressure of air delivered to the manifold, the pressure within the heating chamber can be maintained substantially equal to the atmospheric pressure outside the chamber so that little or no heat will escape from under the side walls of the heating apparatus. This is true even though there is a slight positive pressure within each of the combustion chambers of the: individual heating units. Also, by maintaining the pressure within the heating chamber substantially equal to the outside pressure, minimum air is drawn into the heating chamber from around the peripheral lower edges thereof to minimize the effects of oxidization or combustion of the road surface during heating, and also to substantially minimize the effects of blow out of the respective ones of the radiant heating units. This then provides uniform heat completely beneath the radiant heating appartus as all of the radiant heating units are operating substantially continuously.

In accordance with the principles of this invention the flame from the heating apparatus is directed downwardly from a combustion chamber through a plurality of orifices formed about the periphery of a nozzle structure. The orifices within the nozzle structure have a first portion substantially parallel to the axis of the nozzle and a second portion leading into the first portion through a curved section for directing the products of combustion radially outwardly of the nozzle. A deflector is positioned radialy outwardly of the nozzle and may include portions thereof being downstream of the combustion chamber so that the products of combustion which leave the orifices of the nozzle impinge thereupon and are redirected. The deflector is configurated so as to include a plurality of annular or ring step members and redirect the products of combustion to a predetermined location substantially axially aligned with the combustion chamber but downstream thereof. A target element, preferably of ceramic refractory material or the like, is positioned at the predetermined location and the products of combustion from the deflector unit are focused upon this target element. By focusing substantially all of the products of combustion from the combustion chamber onto the ceramic target intense heating conditions occur and produce substantial increases in the energy level of radiant heat produced. The ceramic target is secured preferably to an inconel screen member and the flame or products of combustion directed outwardly from the target pass over the inconel screen and also heat the same to a relatively high energy state. This produces additional levels of radiant heating energy.

Many other features and advantages of this invention will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawings wherein like reference numerals throughout the various views of the drawings are intended to designate similar elements or components.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a road resurfacing apparatus utilizing the improved heater structure units constructed in accordance with the principles of this invention;

FIG. 2 is a top view of one of the heater units of the apparatus of FIG. 1 with a top wall fragmentary portion broken away to illustrate the grouping of a plurality of discrete heating units within the heating apparatus.

FIG. 3 is an enlarged elevational fragmentary sectional view of a single heating element utilized in the heating apparatus of FIG. 2;

FIG. 4 is a top view of the heating apparatus of FIG. 3;

FIG. 5 is an enlarged fragmentary sectional view illustrating the means of assembling the heating unit of FIG. 3; and

FIG. 6 is an enlarged fragmentary sectional view taken along line 6-6 of FIG. 3 illustrating further the means of assembling the heating unit of this invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to FIG. 1 there is seen a side elevational view of a road resurfacing machine and is designated generally by reference numeral 10. The road resurfacing machine 10 utilizes a plurality of large pneumatic tires or wheels 13 having sufficient contact area with the road surface so that the weight of the large machine is distributed uniformly over the road surface upon which repaving operations are being performed at a relatively low pressure per unit area. As the road resurfacing machine 10 moves forward over a damaged road surface, the front end of the machine will heat and dig up the road surface to a depth of approximately one to two inches more or less. The quantity of old road surface now forming loose pavement is additionally heated so that it becomes substantially compressable under the weight of roller action. Additional quantities of asphalt material may be supplied, as desired, to build up the road surface to the previous height or to a height greater than the old surface if desired. Generally however, the quantity of new asphalt material being added to the old asphalt material is sufficient to replace those quantities which have been depleted as a result of pot holes, or the like. The rate of travel of the machine may be in the order of 8 to 20 feet per minute thereby providing a completely reconstructed road surface upon which traffic can commence substantially immediately after the new road surface has been formed.

A quantity of new asphalt material 14 is delivered via a truck or other suitable transport means 16 into a hopper or receptacle 17 located at the front end of the machine. A conveyor 18, along the top portion of the frame support portion of the machine transports the new asphalt material from the hopper to one or more various work stations. A control station 19 is located intermediate the machine, and an operator is stationed at this point to control the direction of travel as well as the rate of travel of the machine over the road surface. Also, the operator at the control station 19 controls various other functions, such as, the amount of heat supplied to the road surface by various heat supplying burners. One or more diesel engines 20 are mounted at the rear portion of the machine and include various control panel arrangements 20a which may be used to operate hydraulic pumps or compressors. The wheels 13 are motorized by independent hydraulic motors operated by hydrostatic hydraulic supply pumps controlled by the diesel engine and control panel 20a.

However, it will be understood that other drive means may be incorporated without departing from the general aspects of this invention.

A plurality of fuel tanks 21 are mounted on top of the support frame 22 of the machine and are used to carry fuel supplies for both the diesel engine 20 and a pair of longitudinally displaced

radiant heating apparatus

24 and 26. One or more of the fuel tanks 21 may be filled with diesel fuel while one or more of the fuel tanks may be filled with pentane fuel for operating the radiant heating burning units within the

radiant heating apparatus

24 and 26. The pair of road

surface heating units

24 and 26 are spaced sufficiently apart so that the heated road surface can be dug up or excavated and rearranged, as for example. in a closely gathered pile, for additional heating of the dislodged components of the road surface by the second heating apparatus 26. The

manner in which the road resurfacing machine operates is more fully discussed in my related US. Pat. No. 3,361,042, and no further details of the description of operation is deemed necessary herein. However, the details necessary for a complete understanding are understood to be incorporated herein by reference.

The road resurfacing machine 10 includes a pair of spaced apart

heaters

24 and 26, each constructed substantially in the same manner and, therefore, only a single heater will be discussed in detail herein. While a pair of heaters are here illustrated it will be understood that small road resurfacing machines may incorporate a single heating apparatus or larger machines may incorporate three, four, or more such heating apparatus. The heating apparatus 24 includes a heating chamber 28 facing downwardly to be positioned immediately over the road surface to be repaved so that the road surface can be heated to a depth of approximately one to two inches or more thereby softening the asphalt material of the old road surface. After heating the road surface it is excavated by scarfmg or the like with a plurality of cutting points or knives and additional heat is applied to the dislodged asphalt material by the second burner 26.

The heating chamber 28 is formed by a plurality of chamber-forming walls 30 of fabricated construction and a top wall or roof section 31. The bottom of the chamber is open and the downwardly extended peripheral edge portion of the side walls 30 are closely spaced to the road surface so that minimum air gap is maintained during normal operating conditions. The pressure within the heating chamber 28 is maintained substantially equal to orjust slightly above the atmospheric pressure outside the chamber so that no, or very little, heat escapes from the space between the walls 30 and the road surface. Similarly no unwanted oxidizing air will be drawn into the heating chamber as a result of a negative pressure therein.

Positioned above the heating chamber 28 is a fuel mixing chamber 32 which, in turn, is in fluid communication with a pressure blower unit 33. The pressure blower unit 33 supplies a quantity of air under slight pressure so that the air fuel mixture is directed toward a plurality of discrete burner units within the heating chamber 28. While the pressure provided by the blower 33 is relatively low, the air volume moved by the blower may be maintained relatively high for maximum heating of the burners. The air fuel mixture supplied from the fuel mixing chamber 32 is then directed into a distributing manifold section 34 mounted on top of the heating unit 28. The air fuel manifold 34 preferably takes the form of a rectangular chamber having a common wall between the heating chamber and the manifold, and in the illustrated embodiment there are two air fuel manifolds 34 on each of the radiant heating apparatus. These air fuel manifolds are located at or near the outboard sides of the heating apparatus. A plurality of upwardly extending large diameter exhaust stacks 36 are located at each of the four corners of the heating apparatus so that heat from the plurality of discrete radiant heating units within each apparatus can be exhausted upwardly and away from personnel working about the machine as the machine moves over the road surface which is being repaved.

Referring now to FIG. 2 there is illustrated the top view of the radiant heating apparatus 24 and shows clearly the pair of manifold sections 34 near the outboard edges thereof together with their associated fuel mixture chambers 32 and blower means 33. A cut away portion of the top wall of the radiant heating apparatus 24 is illustrated to show the orientation of a plurality of discrete radiant heating units 40 located within the chambers 28. While each of the radiant heating units 40 includes a square or rectangular radiant heating screen element oriented substantially at a 45 angle with respect to the longitudinal and transverse axes of the radiant heating apparatus, it will be understood that other orientations may be incorporated without departing from the spirit and-scope of the present invention. For example, the square screens of the radiant heating units may be oriented in rows and columns, or they may be oriented in circular patterns if desired. Furthermore, the radiant heating screen elements may take configurations other than square, as for example, triangular or round.

Referring now to FIGS. 3, 4, 5, and 6 the details of construction ofa single one of the radiant heating units 40 used within the radiant heating apparatus 24 is illustrated. The radiant heating unit'4l) includes a combustion chamber 41 which receives the proper air fuel mixture ratio from a fuel supply tube 42, here being illustrated as threadedly connected to the combustion chamber by threads 43. In the illustrated embodiment the threads may be of a pipe thread characteristic so as to provide a self-tightening or locking feature as is well known. The air fuel mixture within the combustion chamber 41 developes products of combustion therein which are directed through a nozzle 44. The nozzle 44 has a plurality of radially disposed, arcuately spaced apart orifices 46. The nozzle 44 is threadedly secured to a pipe or receiving member 47 the inner portion of which forms the combustion chamber 41. The nozzle may beheld securely to the pipe 47 by means to be described hereinbelow.

In the preferred embodiment of this invention the orifices 46 each include a first portion 46a which is oriented substantially parallel to the axis of the nozzle and a second portion 46b leading from. the first portion 46a through an arcuately disposed portion 46c. Therefore, the products of combustion which pass through the nozzle 44 have their direction or path of travel changed from substantially vertical to substantially horizontal, preferably being a change of direction of or more so as to be directed upwardly toward the focus surface of a deflector 48.

The deflector 48 may be made of any suitable refractory material, such as a molded ceramic material and includes a focusing surface 49 formed radially outwardly of the orifices 46 but downstream of the combustion chamber 41. The focusing surface 49 is arranged to direct the flames, or products of combustion, from the nozzle 44 downwardly, as indicated by the broken lines 50, so they impinge upon an infrared radiant energy target means 51. Preferably the radiant energy target means 51 includes a target button 52 of ceramic material positioned at a predetermined location beneath the focusing surface 49 to be in registry with the products of combustion as directed thereto along the broken lines 50. Upon impingement of the flame, or products of combustion, onto the ceramic button 52 the flame is redirected radially outwardly along the top surface of a metal screen element 53. Here the metal screen 53 preferably is formed of an inconel material which produces infrared radiant energy when heated by a flame.

Referring now particularly to FIGS. and 6 the means of assembly of the nozzle 44 to the pipe or combustion chamber forming member 47 is more clearly illustrated. A threaded aperture 60 is formed at a given location about the periphery of the pipe through the wall section thereof. The extent of the threaded aperture is sufficient to reach completely through a relatively thick portion of the wall and into that portion of the combustion chamber which communicates with the nozzle 44. A threaded set screw or lock screw 61 is inserted into the threaded aperture and threaded downwardly by means of a socket type tool engaged into a socket 62 formed at one of the set screws. The set screw 61 has the lowermost end portion 63 engaging a peripheral portion 64 of the nozzle 44. This then prevents rotation of the nozzle with respect to the pipe to prevent inadvertent unthreading during normal operation.

Four spaced apart wire leg sructures 70 are arranged to have the top portions thereof bent in a direction transverse to the axis of the nozzle 44 and arranged to fit in a groove 71 located near the top portion of the pipe 47. The wire leg sections have a bent end portion 72 at the top thereof and each bent end portion 72 is welded or brazed, or fastened by other means, to the top portion of an adjacent corresponding wire leg, as shown. The lower portions of the wire leg 70 have bent ends 73 which pass through the screen 53 and support the screen. While a particular wire structure arrangement is illustrated herein for supporting the infrared heating member 51, it will be understood that other support means can be incorporated.

While a single specific embodiment of the present invention has been clearly illustrated in great detail, it will be understood that variations and modifications of this embodiment may be incorporated without departing from the spirit and scope of the novel concepts disclosed and claimed herein.

The invention is claimed as follows:

1. Equipment for heating the upper strata of asphalt concrete pavement, comprising in combination: a heating chamber having chamber-forming walls including a roof adapted to overlie an area of the pavement to be heated by radiant energy heat, said chamber-forming walls including downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced to the pavement, a plurality of radiant heating units positioned within said heating chamber substantially completely to provide a uniform area of radiant heat within said chamber for heating the pavement therebeneath, each of said radiant heating units including, a combustion chamber for connection to an air fuel supply to receive an air fuel mixture therein for burning of the air fuel mixture, nozzle means secured to said combustion chamber, said nozzle means having an axis which is aligned with said combustion chamber,

a plurality of orifices extending through said nozzle means, each of said orifices having a first portion oriented substantially parallel to said axis of said nozzle and a second portion leading from said first portion and directed radially outwardly of said nozzle to change the direction of the products of combustion which pass through said nozzle, a deflector means positioned radially outwardly and axially downstream of said combustion chamber, said deflector means having a portion thereof adjacent said second portion of said orifices to receive the products of combustion therefrom and redirect said products of combustion to a predetermined location axially aligned but longitudinally displaced from said nozzle, and infrared radiant heating target means located substantially in coincidence with said predetermined location to receive the products of combustion from said deflector means and convert said products of combustion substantially entirely to infrared radiant heat energy, said target means comprising an imperforate target element displaced for direct impingement by said products of combustion, and a cross grid screen wire structure extending outwardly thereof.

2. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1, wherein said target element includes a conical refractory target element secured substantially centrally of said cross grid screen wire structure, said ceramic target element being oriented substantially to receive the entire quantity of redirected products of combustion from said deflector means for intense heating thereof, and thereby intense heating of said screen.

3. The equipment for heating the upper strata of asphalt concrete pavement according to claim 2, wherein said screen member is an inconel screen.

4. The equipment for heating the upper strata of asphalt concrete pavement according to claim 2, wherein said radiant heating energy target means is supported by four depending support wires arranged in four quadrant locations about said deflector means, said support wires being bent about said deflector means and directed past said combustion chamber to engage recess grooves formed therein for providing structural support of said infrared radiant target means with respect to said combustion chamber and said nozzle.

5. The equipment for heating the upper strata of asphalt concrete pavement according to claim 4, wherein each of said support wires has a first portion extending longitudinally of said deflector means and a second portion bent radially inwardly across the top of said deflector means to engage the recesses formed in said combustion chamber, said second portion having a bent end to be secured to a corresponding second portion of an adjacent one of said support wires, said first portion having a bent end to pass through and support said screen and said refractory target element.

6. A radiant heating unit comprising in combination, a combustion chamber including means for connection to an air fuel supply which delivers an air fuel mixture to the combustion chamber for burning therein, nozzle means secured to said combustion chamber, said nozzle means having an axis which is axially aligned with said combustion chamber, a plurality of orifices extending through said nozzle means, each of said orifices having a first portion oriented substantially parallel to said axis of said nozzle and a second portion leading from said first portions and directed radially outwardly of said nozzle to change the direction of the products of combustion which pass through said nozzle, a deflector means positioned radially outwardly and axially downstream of said combustion chamber, said deflector means having a portion thereof adjacent the second portion of said orifices to receive the products of combustion therefrom and redirect said products of combustion to a predetermined location axially aligned but longitudinally displaced from said nozzle, and infrared radiant energy target means located substantially in coincidence with said predetermined location to receive the products of combustion from said deflector means and convert said products of combustion substantially entirely to infrared radiant heat energy, said target means comprising an imperforate target element displaced for direct impingement by said products of combustion, and a cross grid screen wire structure extending outwardly thereof.

7. The radiant heating unit as set forth in claim 6, wherein said target element includes a conical refractory target element secured substantially centrally of said cross grid screen wire structure, said ceramic target structure being oriented substantially to receive the entire quantity of redirected products of combustion for intense heating thereof, and thereby intense heating of said screen.

8. The radiant heating unit as set forth in claim 7, wherein said screen member is an inconel screen.

9. The radiant heating unit as set forth in claim 7,

wherein said radiant heating energy target means is supported by four depending support wires arranged in four quadrant locations about said deflector means, said support wires being bent about said deflector means and directed past said combustion chamber to engage recess grooves formed therein for providing structural support of said infrared radiant target with respect to said combustion chamber and said nozzle.

10. The radiant heating unit .as set forth in claim 9, wherein each of said support wires has a first portion extending longitudinally of said deflector means and a second portion bent inwardly across the top of said deflector means to engage the recess formed in said combustion chamber, said second portion having a bent end to be secured to a corresponding second portion of an adjacent one of said support wires, said first portions having a bent end to pass through and support said screen and said refractory target element.

l l= l =l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 1,865,098 Dated FEBRUARY 11, 1975 Q Inventor(s) EARL F. CUTLER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Assignee: "Cutter Repaving Associates, Incorporated" should be --Cut l er Repaving Associates, Incorporated Col. 7, line 21; "s ructures" should be -structures- Signed and Sealed this nineteenth Day of Au t 1975 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN AIICSHHX ()jfl're (rmzmissmncr n] Palenls and Trademarks FORM PC4050 USCOMM-DC 60376-F'69 ".5. GOVERNMENT PRINTING OFFICE 2 I965 0-356-334.

Claims

1. Equipment for heating the upper strata of asphalt concrete pavement, comprising in combination: a heating chamber having chamber-forming walls including a roof adapted to overlie an area of the pavement to be heated by radiant energy heat, said chamber-forming walls including downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced to the pavement, a plurality of radiant heating units positioned within said heating chamber substantially completely to provide a uniform area of radiant heat within said chamber for heating the pavement therebeneath, each of said radiant heating units including, a combustion chamber for connection to an air fuel supply to receive an air fuel mixture therein for burning of the air fuel mixture, nozzle means secured to said combustion chamber, said nozzle means having an axis which is aligned with said combustion chamber, a plurality of orifices extending through said nozzle means, each of said orifices having a first portion oriented substantially parallel to said axis of said nozzle and a second portion leading from said first portion and directed radially outwardly of said nozzle to change the direction of the products of combustion which pass through said nozzle, a deflector means positioned radially outwardly and axially downstream of said combustion chamber, said deflector means having a portion thereof adjacent said second portion of said orifices to receive the products of combustion therefrom and redirect said products of combustion to a predetermined location axially aligned but longitudinally displaced from said nozzle, and infrared radiant heating target means located substantially in coincidence with said predetermined location to receive the products of combustion from said deflector means and convert said products of combustion substantially entirely to infrared radiant heat energy, said target means comprising an imperforate target element displaced for direct impingement by said products of combustion, and a cross grid screen wire structure extending outwardly thereof.

9. The radiant heating unit as set forth in claim 7, wherein said radiant heating energy target means is supported by four depending support wires arranged in four quadrant locations about said deflector means, said support wires being bent about said deflector means and directed past said combustion chamber to engage recess grooves formed therein for providing structural support of said infrared radiant target with respect to said combustion chamber and said nozzle.

10. The radiant heating unit as set forth in claim 9, wherein each of said support wires has a first portion extending longitudinally of said deflector means and a second portion bent inwardly across the top of said deflector means to engage the recess formed in said combustion chamber, said second portion having a bent end to be secured to a corresponding second portion of an adjacent one of said support wires, said first portions having a bent end to pass through and support said screen and said refractory target element.