US3801212A

US3801212A - Heater for asphalt concrete roadways and the like

Info

Publication number: US3801212A
Application number: US00282005A
Authority: US
Inventors: E Cutler
Original assignee: CUTLER REPAVING ASS
Current assignee: CUTLER REPAVING ASS; CUTLER REPAVING ASS INC US
Priority date: 1971-03-30
Filing date: 1972-08-18
Publication date: 1974-04-02
Anticipated expiration: 1991-04-02

Abstract

Disclosed herein is an embodiment of a heater for asphalt concrete repaving apparatus which utilizes fuel, such as pentane, to direct a flame onto a radiant heating element. The flame is redirected radially outwardly along the radiant heating element so the flame will not impinge on the road surface and only radiant heat is used. Such radiant heat will penetrate the road surface to a depth of 1 inch or more in a relatively short period of time whereupon the heated and softened asphalt together with portions thereof beneath the heated portion are excavated. Additional heat is applied to the excavated material to further soften it and small quantities of new asphalt material may be added if desired before the reworked material is again laid to form a road surface.

Description

United States Patent [191 Cutler Apr. 2, 1974 [54] HEATER FOR ASPHALT CONCRETE 3,055,280 9/1962 Neville .L 404/95 ROADWAYS AND THE LIKE 3,221,617 12/1965 Quigg 404/95 3,096,696 7/1963 Reisser 404/95 [75] Inventor: Earl F. Cutler, Lawrence, Kans. 3 372, 2 3 1968 Smarzak 404/95 Assigneez Cutler p g Associates, 2,705,906 4/1955 Fizzell 404/95 Incorporated Lawrence Primary ExaminerNi1e C. Byers, Jr. [22] Filed: Aug. 18, 1972 Attorney, Agent, or Firm--Olson, Trexler, Wolters, [211 App. No: 282,005 Bushnell & Fosse, Ltd.

Related US. Application Data [57] ABSTRACT [63] of 129,404 March Disclosed herein is an embodiment of a heater for as- ]971 phalt concrete repaving apparatus which utilizes fuel,

such as pentane, to direct a flame onto a radiant heatg% 404/95 65: 23 ing element. The flame is redirected radially out- 1 I} c wardly along the radiant heating element so the flame [58] Field of Search 404/95, 77; 239/169, 521,

239 126 271 1 271 2 271 3 3 3 39() W11] not impinge on the road surface and only radiant l 4 heat is used. Such radiant heat will penetrate the road I surface to a depth of 1 inch or more in a relatively short period of time whereupon the heated and soft- [56] References Cted ened asphalt together with portions thereof beneath UNITED STATES PATENTS the heated portion are excavated. Additional heat is 3,021,893 2/1962 Honger 431/329 applied to the excavated material to further soften it 3,067,811 62 st r... 43 X and small quantities of new asphalt material may be 1199568 8/1965 Baumannk 431/328 X added if desired before the reworked material is again 3,199,572 8/1965 B0u1et.... 431/329 laid to form a road u 3,322,179 5/1967 Goodell 431/329 X 1,984,849 12/1934 Van Allen 404/95 X 2l Claims, 10 Drawing Figures PATENTEDAFR 2 1974 I 3.801212 saw u or 5 PATENTEDAPR 21914 3,801,212

SHEET 5 BF 5 'FIG.9

us I us HEATER FOR ASPHALT CONCRETE ROADWAYS AND THE LIKE REFERENCE TO RELATED APPLICATION This is a continuation-in-part of my earlier filed copending application Ser. No. 129,404 filed Mar. 30, 1971, now U.S. Pat. No. 3,724,445.

BACKGROUND OF THE INVENTION This invention relates generally to roadway resurfacing apparatus, and more particularly to heating units utilized as one or more work stations in such roadway resurfacing apparatus.

This invention deals with substantial improvements in my earlier filed copending application Ser. No. 129,404filed Mar. 30, 1971 and the entire subject matter of this earlier application is included herein by reference. Road surfacing apparatus as set forth in my US. Pat. No. 3,361,042 provides means for quickly and inexpensively resurfacing roadways made of asphalt concrete materials, or the like. The apparatus may be eightto 12 feet wide and 40 to 50 feet long and moved 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 immediately freely available for vehicular traffic within a matter of minutes after completion.

The heater apparatus 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 nonoxidizing environment consisting substantially of all radiant heat so that heat penetration is obtained to a depth of 1 inch or so below the surface. This is followed by scarifying deeply to excavate and disarrange the material heated by the first step. Then piling the disarranged material for maximum surface exposure so it can be further heated, this heat being substantially entirely of radiant heat as in the first instance. Then if needed adding very minor amounts of conventional tack coat to help weld the total hot top mixture to the substraight from which the heated material was removed. This is followed by tamping and screeding which, in turn, is followed by compacting as by conventional rolling means.

The heater apparatus may also be used as an attachment to a tractor or the like especially where it is desired to heat relatively small areas of a roadway for patches or other repairs.

Heretofore, heating of the road surface was accomplished in a flame which produced a nonoxidizing atmosphere so that the temperature of the road surface could be elevated higher than the material could experience in 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 the road surface, the amount of fuel required was substantial.

SUMMARY OF THE INVENTION apparatus for road repaving machinery which provides substantially one hundred percent radiant heat which will raise the temperature of the road surface to about 300F to a penetration depth of about 1 inch or more.

Briefly, the heating apparatus of this invention may form two or more stations of the road repaving machine and each heating apparatus preferably is of the same structural arrangement. Therefore, only details of a single heating apparatus will be set forth in great particularity. The heating apparatus is provided with a fuel receiving manifold which ispositioned over a heating chamber and is rectangular in configuration like the heating chamberIA plurality of discrete fuel burning elements have conduit portions extending through the heating chamber and into the manifold chamber to receive a mixture of hot gas and air which is a combustible mixture that is burned at the heating nozzle. 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 deliveryv combustion process. Therefore, the pressure within the heating chamber can be maintained substantially equal to that of the atmospheric pressure outside the chamber and little or no heat will escape from under the side walls thereof. 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 and minimum oxidation or actual combustion on the road surface is the result.

In accordance with the principles of this invention the flame from the heating apparatus is directed downwardly and then deflected laterally or radially outwardly so as to fall across substantially the entire area of a radiant heating element which converts the heat from the flame to radiant heat. The radiant heating element is positioned adjacent the road surface and thereby provides red and infrared heat energy to penetrate the road surface to depths of 1 inch or more, this being accomplished in a relatively short period of time and with the use of a minimum of fuel.

Many other objects, 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 roadbed resurfacing apparatus utilizing the heater structure of this invention;

'FIG. 2 is a perspective fragmentary view of a heater structure which is constructed in accordance with this invention;

FIG. 3 is a side elevational sectional view of the heater structure of FIG. 2;

FIG. 4 illustrates an air control mechanism for controlling the volume of air delivered to an air fuel mixing chamber of the heater structure of this invention;

FIG. 5 is an enlarged fragmentary view showing a dis crete heater unit mounted within the heater structure of this invention;

FlG. 6 shows an alternate flame detectorarrangement which can be used in the heater unit of FIG. 5;

FIG. 7 is a top view of the heater arrangement of FIG. 3 showing the placement of the discrete heater units and the associated radiant heating elements together with the air blower and manifold structure positioned above the heater chamber;

FIG. 8 is a plan view of an alternate form of manifold construction used in the heater apparatus of this invention;

Detailed Description of the Illustrated Embodiment Referring now to FIG. 1 there is seen a side view of a road resurfacing equipment and is designated generally by reference numeral 10. The road resurfacing equipment It) utilizes a plurality of large. pneumatic wheels 13 having sufficient contactsurface area so that the weight of the machine is distributed uniformly. As the road resurfacing equipment 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 oneto two inches more or less. The quantity of old road surface now forming loose pavement is additionally heated so that it becomes substantially compressible 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 road surface. The rate of travel of the machine may be in theqorder of eight to 25 feet per minute thereby providing a complete reconstructed road surface upon which vehicular traffic can commence substantially immediately after the new road surface has been formed.

16 into a hopper or receptacle 17 at the front end of the machine. A conveyor 18 along the top portion of the frame transports the new 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 there to control the direction of travel as well as the rate of travel'of the machine. Also, the operator at the control station 19 controls various functions such as the amount of heat supplied to the road surface by the various burners. One or more diesel engines 20 are mounted at the rear portion of the machine and include various control panels 20a which operate hydraulic pumps or compressors. The wheels 13 are motorized by independent hydraulic motors operated by hydrostatic hydraulic supply pump control mechanisms. A plurality of fuel tanks 21 are mounted on top of the support frame 22 of the machine and are used to carry fuel A quantity of new material 14 is delivered via a truck supplies for both the diesel engine '20 and for the

burners

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 burners. The pair of

road surface heaters

24 and 26 are spaced sufficiently apart so that the heated road surface can be dug up and rearranged for additional heating of the dislodged components of the road. The manner in which the road resurfacing apparatus 10 operates is more fully discussed in my US. Pat. No. 3,361,042 and no further detailed description of operation is deemed necessary herein.

The road resurfacing apparatus 10 includes a pair of

heaters

24 and 26 each constructed substantially in the same manner and therefore only a single heater will be discussed in detail. The heater 24 includes a heat 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 inch or more thereby softening the material forming the old road surface. After heating of the road surface 'it is excavated by scarifying or the like with a plurality of cutting points or knives and additional heat is supplied 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 31. The bottom of the chamber is open and the downwardly extending peripheral edge portions of the side walls are closely spaced to the road surface so that minimum air gap is obtained. the pressure within the heating chamber 28 is maintained substantially equal to the atmospheric pressure outside of the chamber so that no heat escapes from the space between the walls and the road surface, and similarly, no

unwanted oxidizing air will be drawn into the heating chamber from the outside atmosphere.

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 burners within the heating chamber 28. While the pressure provided by the plower 33 is relatively low, the air volume moved by the blower is maintained relatively high for maximum heating of the bumers. The air fuel mixture supplied from the fuel mixing chamber 32 is then directed into a distributing manifold 34 mounted on top of the heating chamber 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. A plurality of upwardly extending large diameter exhaust stacks 36 are located at each of the four corners of the burner so that heat formed within the heating chamber 28 can rise through the exhaust stacks and be expelled at a level substantially above street level so that workmen about the machine are not subjected to the extreme heat.

Referring now to FIG. 2 a detailed fragmentary perspective view of the heater 24 is illustrated, it being understood that the side of the heater 24 is typical with respect to the other side of the heater. The side walls 30 include a plurality of reinforcing members 37 positioned vertically about the side walls. A top and bottom edge 38 also form reinforcing members about the side walls. The manifold 34 is in fluid communication with an enlarged manifold portion 340 which-forms the top wall of the heating chamber. The manifold portion 340 can be formed either as an integral part of the heating chamber as shown, i.e. formed by the top wall thereof, or it can be formed as a separate unit mounted on top of the heating chamber. The fuel mixing chamber 32 includes a top 40 which has a flange 41 fastened thereto for supporting the blower 33. The blower 33 has the output portion thereof 33a in direct fluid communication with a manually adjustable flow control valve 42. The flow control valve 42 is adjustable to select the proper volume of air directed to the manifold 34.

To insure that the air fuel mixture directed to the burners within the heat chamber 28 is expanded to the maximum extent, an air heat pipe 43 is in fluid communication between one of the exhaust stacks 36 and the outlet port 33a of the blower 33. In the illustrated embodiment the connection to the outlet 33a is made below the flow control valve 42, it being understood that this hot air connection can be made above the flow control valve, if desired. A fuel line 44 is connected to the fuel mixing chamber 32 and therein the fuel, preferably pentane or the like, is admixed with the air from the blower 33 and delivered to the first manifold portion 34 and therefrom to the second manifold 34a. The fuel delivered through the line 44 is heated by a preheater unit, to be described hereinbelow, which is mounted within the heating chamber 28. Therefore, fuel from the tanks 21 is supplied to the inlet line 44a and directed through the preheater unit and therefrom to the fuel line 44 and into the mixing chamber 32. By so preheating the fuel and heating a portion of the air supplied to the mixing chamber, maximum expansion of the air fuel mixture is obtained before combustion. This enables the air fuel mixture to ignite with minimum expansion of gases so that little or no pressure is obtained within the heating chamber.

Referring now to FIG. 3 there is seen a side elevational sectional view showing more clearly the details of construction of the burner of this invention. Here it can be seen that the mixing chamber 32 is in open communication with the manifold 34 by means of a large opening 46 through the top wall of the manifold. I-Iowever, it will be understood that the top wall of the manifold can be provided with a plurality of small holes rather than the large opening 46. Similarly, the top wall of the manifold portion 34a is provided with an opening 47 to receive the quantity of air fuel mixture from the manifold 34. Similarly, this large opening 47 can be replaced by a top wall portion having a plurality of small holes formed therein. The air fuel mixture from the chamber 32 is illustrated by the plurality of arrowed lines directed through the manifold.

The bottom wall of the manifold portion 34a is provided with a plurality of threaded members 38, they being nut-like units or the like secured, as for example by welding, to the inner wall portion of the manifold. The threaded units 48 receive burner units 49 therein, the burners being directed downwardly toward the pavement to be heated. Each of the burner units 49 includes a radiant heat element 50 upon which the open flame of the burner is impinged so that the flame heat produced by the burner is converted to radiant heat. The radiant heating elements 50 cause thepavement to be heated to a depth of approximately 1 inch or more, this being indicated by the portion 52 of the pavement shown in FIG. 3. Preferably, the radiant heating elements 50 are formed of screen-like members of Inconel material which is a nickel-based, heat-and-oxidizationresistant material having approximately 13 percent chromium, 6 percent iron and small amounts of manganese, silicon and copper. It will be understood that other similar radiant heating material may be utilized if desired.

Also mounted within the heating chamber 28 is a preheater unit 53, which as mentioned above, has a fuel input line 44a connected to one portion thereof and the fuel output line 44 connected to the fuel mixing chamber 32. The preheater unit 53 substantially increases the temperature of the fuel before it is delivered to the mixer chamber 32 so that maximum expansion of the fuel is obtained before combustion thereof.

Referring now to FIG. 4 there is seen a detailed sectional view of the air flow control valve 42 which is connected in the output portion 33a of the blower 33. The air flow control valve 42 includes a fixed flange portion 56 formed on the rectangular conduit section 57. A plurality of holes 58 are formed near the periphery of a portion of the flange 56 to receive a pin 59 secured to an extended handle portion 60. The handle is used to rotate a vein element 61 so that a port 62 therethrough is positioned either in line or transverse to the flow path through the conduit section 57. The hot air inlet 43 is positioned below the adjustable vein 61 and admits a quantity of heated exhaust air from one of the vertical exhaust stacks 36, FIG. 2. While a cross vein type of air flow control device is shown herein, it will be understood that any suitable air flow control mechanism can be used in its place.

Referring now to FIG; 5 there is seen an elevational sectional view of one of the burner units 49 which is mounted within the heating chamber 28. Here it canbe seen that the threaded fastener 48 has a metering orifice 69 substantially in alignment with the opening through a pipe 70. Air fuel mixture within the manifold 34a is delivered through the metering orifice 69 and the pipe 70 to enlarged chamber'portion of a cylinder 72. Within the cylinder 72 is mounted a baffle element 73 which has an enlarged aperture 74 centrally thereof. The baffle 73 serves further to agitate and mix the air fuel mixture before it is delivered to the lower burning portion of the cylinder 72 wherethe air fuel mixture is ignited. Secured to the bottom peripheral portion of the cylinder 72 are a plurality of support plates 76 having upwardly turned end portions 77a and radially outwardly turned bottom portions 77b for securing to the cylinder and radiant heating element 50, respectively. The support legs 76 are secured by nut and bolt fasteners 78, which may include suitable washer elements as desired. The flame from the cylinder 72 is directed toward a deflector element 80 which has a curved surface exposed to the flame so that the flame is directed radially outwardly across the radiant heating element 50 to more efficiently heat the same. The deflector element 80 is mounted to the screen by means of a bolt 81 and nut 82.

The deflector element 80 may take several different configurations to cause the flame to be directed radially outwardly over the screen element. For example, FIG. 6 shows an alternate form of a deflector element which is designated generally by reference numeral 800. The deflector element 80a, in this instance, is mounted below the radiant heating element 50 so that the aperture thereof is in close proximity to the nut 82 rather than the head of the bolt 81.

FIG. 7 illustrates the orientation of the various radiant heating elements 50, they being substantially square in configuration and arranged diagonally within the heating chamber 28, this being shown in the broken away portion of the drawing of FIG. 7. This type of configuration insures that maximum radiant heating is directed toward the pavement beneath the same. Also shown in FIG. 7 is the detail of the preheater unit 53,

it being formed of a plurality of windings of tubular material which supplies the fuel to the mixing chamber 32. The coils of the tubular material may be wrapped about a ceramic support member 90 which, in turn, is bolted in place under the heating chamber. FIG. 7 also shows that one heating element may be provided with a pair of manifold sections 34 and blowers 33. The second manifold and blower element units are designated with a prime adjacent each of the numbers.

Referring now to FIGS. 8 and 9, there is seen an alternate heater construction designated generally by reference numeral 100. The heater 100 includes a main manifold chamber 101 which is in fluid communication with a distribution conduit 102 extending along the major length of the heater. Extending transversely of the distribution conduit 102 are a plurality of manifold

fuel distribution arms

103 and 104 of different lengths, the shorter being the distribution arms 103- and the longer being the distribution arms 104. An air fuel mixture is delivered to the manifold chamber 101 by means of an inlet duct 106. By thus providing relatively small volume distribution arms and feed conduit from the main manifold chamber 101 the amount of air fuel mixture which is captured therein at any given time is substantially reduced so that a more economic and safe burner arrangement is provided.

The heater unit 100 is provided with a pair of

brackets

107 and 108 for mounting the heater to a road refinishing machine or to a tractor, as desired. Therefore, the heater unit 100 can be used for repairing limited areas of road surface as mentioned above.

Seen in FIG. v is a cross-section of a modified heater unit secured to the top wall 109 which is of refractory material and is heated by means of the deflected flame. This refractory-material also causes radiant heat. to be generated and directed downwardly toward the road surface to form a more efficient heating unit.

'A plurality of heaters 110 have a combustion chamber 111, partially embedded into the refractory wall 109, as best seen in FIG. 10, and a fuel feed pipe 112 extending therefrom threadedly to engage a metering orifice member 113 located within the distribution

arm manifold portions

103 and 104. In this instance a spark arrester safety screen 1 16 is inserted into the feed pipe 112 immediately downstream of the metering orifice 113 so that inadvertent backfire into the manifold system is prevented.

A conical deflection member 117 is fastened to the radiant heating element 118 by a bolt 119 threadedly engaged therewith. The conical deflection member preferably is of high temperature refractory material and fashioned to cause a change in direction of the flame emanating from the combustion chamber 111. The flame then passes laterally across the radiant heating element so that radiant heat is directed toward the road surface. This arrangement substantially minimizes the presence of a flame between the radiant heating element andthe road surface, which flame would otherwise tend to insulate the road surface from the maximum heating by the radiant heat.

As mentioned above, there are two spaced apart heating structures associated with the road resurfacing apparatus 10 of FIG. 1, it being understood that more heating units can be incorporated as desired. Also a single heating structure can be used on the back of a tractor or the like to heat limited areas of road surface for small repairs. While several specific embodiments of the radiant heating structure of this invention are disclosed herein it will be understood that variations and modifications thereof may be effected without departing from the spirit and scope of the novel concepts as defined by the appended claims.

The invention is claimed as follows:

1. Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising in combination: a chamber having chamber-forming walls including a roof adapted to overlie an area of the'pavement to be heated by radiant heat, said chamber-forming walls including downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced to the pavement, heater means positioned within said chamber for directing a flame toward the pavement, and radiant heating element means positioned within said chamber to be at all times between the products of combustion from said heater means and the pavement being heated, said radiant heating element means receiving the flame from said heater means, and redirecting the flame laterally and converting such flame heat to radiant heat, and exhaust manifold means in communication with said chamber at a point above said radiant heating element means to remove the products of combustion, whereby the pavement is heated to a depth greater than otherwise obtained by a direct flame from said heater means.

2. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 wherein .said heating means comprises a plurality of discrete heating nozzles positioned within said chamber and di- I rected toward the pavement, and wherein said radiant heating element means include a corresponding plurality of discrete radiant heating elements secured to the underside of each of said nozzles. I

3. The equipment for heating the upper strata of asphalt concrete pavement according to claim 2 wherein said radiant heating elements are formed of a screenlike structure adapted to radiate energy of long red and infra-red wave lengths.

4'. The equipment for heating the upper strata of asphalt concrete pavement according to claim 3 wherein said radiant heating elements are formed of screen-like structures of heat-and-oxidation-resistant nickel alloy.

5. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 further including air blower, supply means associated with said heating means, said air blower supply means including to redirect the flame from said heating element means radially outwardly along the top surface of said radiant heating element means so that maximum heating thereof is effected and no direct flame impinges upon the pavement being heated.

7. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 further including a fuel distributing manifold positioned about said chamber wherein said heating means includes a plurality of discrete heating elements each having an orificed end thereof inserted into said fuel distribution manifold, and further including adjustable air supply means connected to said fuel distributing manifold for admixing a variable supply of air with the fuel to be burned.

8. The equipment for heating the upper strata of asphalt concrete pavement according to claim 7 further including preheating means positioned within said chamber adjacent said heating menas, said preheating means having an output end connected to said fuel distribution manifold for delivering thereto a quantity of preheated fuel to be mixed with the air supply prior to delivery to said heating means.

9. The equipment for heating the upper strata of asphalt concrete pavement according to claim 7 wherein said fuel distribution manifold is of substantially the same size and configuration as said chamber, said fuel distribution manifold being positioned above and closely spaced to said chamber.

10. Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising in combination: a heating chamber having chamber-forming walls including a roof adapted to overlie and area of the pavement to be heated by radiant heat, said chamberforming walls including downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced to the pavement, a fuel distribution manifold positioned over said heating chamber and closely spaced thereto, said fuel distribution manifold having an air-fuel mixing chamber at the upper end thereof, a source of fuel connected to said air-fuel mixing chamber, a variable volume air supply connected to said air-fuel mixing chamber, a plurality of discrete heating nozzles positioned within said heating chamber for directing a flame toward the pavement, said heating nozzles each having a short conduit portion extending from said heating chamber into said fuel disribution manifold, and radiant heating element means positioned within said chamber to be at all times between the products of combustion from said heating nozzles and the pavement being heated, said radiant heating element means receiving the flame from said heating nozzles and redirecting the flame radially outwardly across said radiant heating element means for converting the flame heat to radiant heat, and exhaust manifold means in communication with said chamber at a point above said radiant heating element means to remove the products of combustion.

11. The equipment for heating the upper strata of asphalt concrete pavement according to claim 10 wherein each of said heating nozzles includes a cylindrical body connected to the bottom of each conduit, a baffle element positioned radially inwardly within said body to create a turbulent condition of the flame as it leaves the nozzle, a plurality of radially outwardly and depending leg elements secured to said cylindrical body, and means securing said radiant heating element means to said legs.

12. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 1 further including flame deflection means secured to said radiant heating element means and in registry beneath said body so that the flame therefrom will impinge upon said deflector and be directed radially outwardly along said radiant heating element means.

13. The equipment for heating the upper strata of asphalt concrete pavement according to claim 10 further including fuel preheating means arranged between the fuel supply and said air-fuel mixing chamber for preheating the fuel mixture so that minimum expansion of gas occurs when the fuel mixture is burned.

14. Equipment for heating asphalt pavement or the like comprising chamber means for closely overlying an area to be heated, heater means associated with said chamber means for directing a heating flame within said chamber means and a radiant heating element mounted within the chamber means to be at all time between the products of combustion from said heater means and the pavement being heated for receiving heat from said flame and radiantly heating the pavement, and exhaust manifold means in communication with said chamber means at a point above said radiant heating element means to remove the products of combustion therethrough.

15. In the equipment of claim 14 wherein said heating means is disposed for directing flame downwardly toward pavement and said radiant heating element, and

' means for deflecting the flame along said radiant heating element and for preventing direct impingement of the flame against said pavement.

16. In the equipment of claim 15 wherein said radiant heating element is a screen-like structure.

17. In the equipment of claim '16 including a plurality of said heating means and radiant heating elements, 7

and mounting means for deflecting a flame and spaced in a predetermined pattern within said chamber means.

18. In the equipment of claim 14, further including, fuel feed manifold means having a main fuel input manifold section positioned over said chamber means and occupying an area less than said chamber means, a distribution conduit connected to said fuel input manifold section and extending across at least one dimension of said chamber means on top thereof, and a plurality of hollow arms connected to and in the .fluid communication with said distribution conduit to feed air fuel mixture to said heater means assembled within said chamber means.

19. In the equipment of claim 18 wherein said heater means includes a plurality of discrete heating units each including a threaded pipe threadedly engaging a metering orifice secured to the interior of the respective associated hollow arms for receiving air fuel mixture therefrom.

20. In the equipment of claim 19 further including a coiled screen, spark arrester element positioned within said pipe to prevent backfire from said heater units into said hollow arms.

21. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1, wherein said exhaust manifold means passes through said roof of said chamber.

Claims

1. Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising in combination: a chamber having chamber-forming walls including a roof adapted to overlie an area of the pavement to be heated by radiant heat, said chamber-forming walls including downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced to the pavement, heater means positioned within said chamber for directing a flame toward the pavement, and radiant heating element means positioned within said chamber to be at all times between the products of combustion from said heater means and the pavement being heated, said radiant heating element means receiving the flame from said heater means, and redirecting the flame laterally and converting such flame heat to radiant heat, and exhaust manifold means in communication with said chamber at a point above said radiant heating element means to remove the products of combustion, whereby the pavement is heated to a depth greater than otherwise obtained by a direct flame from said heater means.

2. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 wherein said heating means comprises a plurality of discrete heating nozzles positioned within said chamber and directed toward the pavement, and wherein said radiant heating element means include a corresponding plurality of discrete radiant heating elements secured to the underside of each of said nozzles.

3. The equipment for heating the upper strata of asphalt concrete pavement according to claim 2 wherein said radiant heating elements are formed of a screen-like structure adapted to radiate energy of long red and infra-red wave lengths.

4. The equipment for heating the upper stratA of asphalt concrete pavement according to claim 3 wherein said radiant heating elements are formed of screen-like structures of heat-and-oxidation-resistant nickel alloy.

5. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 further including air blower supply means associated with said heating means, said air blower supply means including a variable air flow output for adjusting the turbulence of the flame produced by the heating means, whereby the pressure within said chamber is maintained substantially balanced with the atmospheric pressure externally of said chamber about the closely spaced edges of said side walls.

6. The equipment for heating the upper strata of asphalt concrete pavement according to claim 1 further including deflector means positioned between said heating means and said radiant heating element means to redirect the flame from said heating element means radially outwardly along the top surface of said radiant heating element means so that maximum heating thereof is effected and no direct flame impinges upon the pavement being heated.

10. Equipment for heating the upper strata of asphalt concrete pavement, or the like, comprising in combination: a heating chamber having chamber-forming walls including a roof adapted to overlie and area of the pavement to be heated by radiant heat, said chamber-forming walls including downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced to the pavement, a fuel distribution manifold positioned over said heating chamber and closely spaced thereto, said fuel distribution manifold having an air-fuel mixing chamber at the upper end thereof, a source of fuel connected to said air-fuel mixing chamber, a variable volume air supply connected to said air-fuel mixing chamber, a plurality of discrete heating nozzles positioned within said heating chamber for directing a flame toward the pavement, said heating nozzles each having a short conduit portion extending from said heating chamber into said fuel disribution manifold, and radiant heating element means positioned within said chamber to be at all times between the products of combustion from said heating nozzles and the pavement being heated, said radiant heating element means receiving the flame from said heating nozzles and redirecting the flame radially outwardly across said radiant heating element means for converting the flame heat to radiant heat, and exhaust manifold means in communication with said chamber at a point above said radiant heating element means to remove the products of combustion.

12. The equipment for heating the upper strata of asphalt concrete pavement according to claim 11 further including flame deflection means secured to said radiant heating element means and in registry beneath said body so that the flame therefrom will impinge upon said deflector and be directed radially outwardly along said radiant heating element means.

15. In the equipment of claim 14 wherein said heating means is disposed for directing flame downwardly toward pavement and said radiant heating element, and means for deflecting the flame along said radiant heating element and for preventing direct impingement of the flame against said pavement.

17. In the equipment of claim 16 including a plurality of said heating means and radiant heating elements, and mounting means for deflecting a flame and spaced in a predetermined pattern within said chamber means.

18. In the equipment of claim 14, further including, fuel feed manifold means having a main fuel input manifold section positioned over said chamber means and occupying an area less than said chamber means, a distribution conduit connected to said fuel input manifold section and extending across at least one dimension of said chamber means on top thereof, and a plurality of hollow arms connected to and in the fluid communication with said distribution conduit to feed air fuel mixture to said heater means assembled within said chamber means.