Exhaust manifold for asphalt concrete heating apparatus

[57] ABSTRACT

The embodiment of the invention disclosed herein is directed to equipment for heating the upper strata of asphalt concrete pavement. The equipment includes a chamber having a chamber-forming wall including a roof adapted to overlie an area of the pavement to be heated, and wherein the chamber-forming walls provide downwardly extending peripheral side portions having lower edges adapted to be closely spaced from the pavement. Heater means are positioned within the chamber so formed for heating the pavement therebeneath. A horizontally disposed exhaust manifold unit is secured to each side of the roof of the heating chamber and directed forwardly of the chamber. The exhaust outlet opening of the exhaust manifold is located at the forward portion of the chamber and includes a downwardly directed outwardly flaring portion through which the hot gases emanating from the exhaust manifold are directed to the surface of the asphalt concrete pavement in front of the heating unit to preheat the pavement. The outwardly directed flaring configuration of each of the exhaust manifolds provide means for preheating the edge most portion of the area beneath the chamber.

Claims, 5 Drawing Figures

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EXH AUST MANIFOLD FOR ASPHALT CONCRETE HEATING APPARATUS

BACKGROUND OF THE INVENTION

This invention relates generally to equipment for heating the upper strata of asphalt concrete pavement of roadways, or the like, and more particularly to an improved exhaust manifold structure used in conjunction with such heating apparatus.

This invention deals with substantial improvements in my earlier filed co-pending application Ser. No. 1 29,4()4, filed Mar. 30, 197 1, the entire subject matter of which is included herein by reference to the extent needed for a complete teaching of road resurfacing equipment. Also, road resurfacing apparatus as set forth in my U.S. Pat. No. 3,361,042 teaches an apparatus for quickly and inexpensively resurfacing roadways made of asphalt concrete materials or the like, and the information in this patent, to the extent needed tor a complete teaching of this application, is herein included by reference. The size of the apparatus for resurfacing roadways may be in the order of about 8 to 1 2 feet wide and in the order of about 40 to 50 feet long, and move along the roadway at a relatively slow rate so that during a single continuous pass over the surface of the roadway, the old road surface in front of the repaving apparatus is excavated and converted to a refinished road surface at the rear of the resurfacing apparatus. A distinct advantage of repaving apparatus of this type is that the finished repaved strip of roadway is substantially immediately available tor vehicular traffic thereby minimizing the amount of time during which the roadway is unusable.

The heater apparatus of this invention is advantageously used in road repaving machinery which performs the following functions during the repaving process. First, the road surface is heated to an elevated temperature by a non-oxidizing environment consisting substantially of all radiant heat so that heat penetration of the asphalt is obtained to a depth of one inch or more below the surface. This is followed by a scarifying operation which deeply excavates the asphalt surface and dislodges the material heated by the first step. Then a piling operation may be performed to pile the disarranged asphalt material for maximum surface exposure so it can be further heated by a second heating operation, this heating being also substantially entirely of radiant heat. Then, if needed, a quantity of asphalt material as well as minor amounts of conventional tack coat may be applied to help weld the total hot top mixture of the asphalt to the substrate from which the heated material was removed. This is followed by a tamping and screeding which, in turn, is followed by a compacting by conventional roller means, which may be part of the entire apparatus, or which may be a separate unit following the apparatus.

Furthermore, it will be understood that the radiant heating units themselves may be formed as part of an attachment for a tractor or truck to be transported to a particular locality whereat minor road repairs are to be made.

Heretofore, heating apparatus of this particular characteristic included upwardly standing tubular exhaust stacks through which, the hot gases and products of combustion are discharged trom the heating chamber. While working on roadways in open areas where there are no trees or other objects, such as telephone or power lines, extending over the road surface, there is no apparent danger that can be encountered as a result of these hot gases. However, when utilizing the heating equipment of this type in areas where relatively low oxerhanging trees extend immediately over the roadway, and where other objects such as telephone and power lines extend over the roadway, these hot gases from the upstanding exhaust stacks cause burning ot the leaves on the tree, as well as burning or charring of the insulation on the electrical wires extending over the roadway.

SUMMARY OF THE INVENTION

Accordingly, it is among the objects of this invention to provide a new' and improved heating apparatus for use in road repaving machines as described above wherein the hot exhaust gases front a heating chamber are transferred through a horizontally disposed exhaust manifold unit to emanate from an exhaust opening ot the manifold in a downwardly direction in front ot the heating apparatus to function as a preheating device.

It is another object of this invention to provide a new and improved heating apparatus wherein the heating units of this invention can be utilized in areas where low overhanging branches of trees as well as overhead power lines are not effected by hot exhaust gases from upstanding exhaust stacks.

Briefly, the heating apparatus of this invention is formed of a chamber having chamber-forming walls including a roof adapted to overlie the area ot the pavement to be heated. The chamber-forming walls include downwardly extending peripheral side portions having lower edges thereof adapted to be closely spaced from the pavement so as to substantially completely prevent heat within the heating chamber from coming outwardly of the chamber, and to substantially prevent ambient atmosphere from entering the chamber. The hot gases and products of combustion formed within the chamber pass upwardly through a plurality of aligned tubes which form a conduit extending between the chamber and passing through the roof thereof. These tubes extend into a horizontally disposed exhaust manifold which includes means tor providing a direction of travel of the hot gases through the manifold.

The manifold includes a baffle extending therealong and dividing the manifold into a cold-air passage chamber and a hot-gas passage chamber. The baffle extends from the closed end of the manifold and is directed to the open end thereof in a manner to progressively change the cross-sectional area of the two chambers, the area being a progressively increasing area trom the closed end to the open end within the hot-gas chamber and a progressively decreasing area trom the closed end to the open end in the cold-air passage chamber. Near the closed end of the manifold in fluid communication with the cold-air passage chamber is provided means for connection to a source of air which is under pressure. A plurality of ports provided with flutes directed angularly within the manifold from the cold-air passage chamber to the hot-gas passage chamber arc provided so that cold air flow occurs into the hot-gas passage chamber in the direction from the closed end of the manifold to the open end of the manifold. This then provides a means by which the inherent tendencies for hot gases to go in an upward direction can be conveyed to a horizontal direction along the extent ot the exhaust manifold and directed outwardly and

3,874,366 downwardly through a turned flared exhaust opening at the front of the heating chamber.

In accordance with the principles of this invention there are provided two such horizontally disposed exhaust heating manifolds, one on each side of the heating chamber, and extending forwardly thereof. Each of the exhaust manifolds is provided with a downwardlyturned outwardly flared exhaust opening so that the asphalt concrete pavement immediately in front of and beneath the heating chamber is preheated to a lateral extent to insure proper heating at the edge most portions ot the asphalt concrete pavement under the chamber.

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 numberals 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 heating apparatus wherein horizontally disposed exhaust manifolds are used in accordance with the principles of this invention;

FIG. 2 is a fragmentary perspective view illustrating the position ot the horizontally disposed exhaust manifold located on just one side of the heating apparatus, it being understood that a second manifold is located at the other lateral extremity of the heating chamber;

FIG. 3 is a top view of the heating apparatus of this invention utilizing the new and improved exhaust manifold configuration, here two exhaust manifolds are illustrated, one on each side of the heating chamber unit;

FIG. 4 is a side elevational sectional view of a heating apparatus of this invention wherein the new and improved horizontally disposed exhaust heating manifold is utilized; and

FIG. 5 is a fragmentary sectional view taken along line 5—5 of FIG. 4 illustrating the general configuration of the conduit tubings communicating between the heating chamber and the horizontally disposed exhaust manifold.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Referring now to FIG. 1 there is seen a side view of a road resurfacing apparatus wherein the new and improved structural arrangements of this invention are utilized, this road resurfacing apparatus being here designated generally by reference numeral 10. The road resurfacing apparatus 10 utilizes a plurality of large pneumatic tires or wheels 13 having sufficient surface area in contact with the roadway so that the entire weight of the apparatus is distributed uniformly over a relatively large area, thereby reducing the load per unit area of the resurfacing equipment. As the road resurfacing equipment 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 or 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 the roller action. Additional quantities of asphalt material may be supplied as desired to build up the road surface to a previous height, or to a height greater than the old road surface. The rate of travel of the machine may be in the order of about 8 to 25 feet per minute, thereby providing a completely reconstructed road surface upon which vehicle traffic 5 can commence substantially immediately after the road surface has been formed.

A quantity of new material 14 is delivered, via a truck, or the like, 16, into a hopper or receptacle 17 at the front end of the machine. A conveyor 18 formed 10 along the top portion of the frame structure transports this material from the hopper to one or more of various work stations. A control station 19 is located substantially intermediate the machine, and an operator, not shown, is positioned at this control station to control 15 the direction of travel, as well as the rate of travel of the machine. Furthermore, the operator located at station 19 controls various functions of the apparatus such as the amount of heat supplied to the road surface by the various road heating burners associated therewith.

One or more diesel engines 20 are provided at the rear portion of the machine and include various control panels 20« which operate hydraulic pumps or compressors. The particular structural configuration of the road repaving apparatus 10 illustrated herein provides that ²·⁵ the wheels 13 be motorized by independent hydraulic motors which are operated by the hydrostatic hydraulic supply pumps energized by the diesel engine 20. While this particular type of motive power is preferred, it will be understood that other types of motive power may be ³⁽⁾ utilized without departing from the novel 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 carrylarge quantities of fuel for both the diesel engine 20 and ³⁵ for a pair of spaced apart heating units 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 tilled with pentane fuel for operating the burners associated with the heating units 24 and 26. The pair of road sur⁴θ facing heating units 24 and 26 are spaced sufficiently apart so that the heated road surface therebetween can be dug up and rearranged for additional heating of the dislodged components of the road surface. Therefore, the heating apparatus 24 initially heats the road surface to a depth of about one or two inches and the space between the heating units 24 and 26 provides scarifying means for digging up the road surface. The subsequent heating is then accomplished by the second burner 26. The manner in which the road resurfacing apparatus 10 operates is more fully disclosed in my U.S. Pat. No. 3,361,042, and no further detailed description of operation is deemed necessary herein.

The pair of heating units 24 and 26, each are constructed substantially identically, and therefore, only a single heating unit will be discussed in great detail. Therefore, referring now to FIG. 2 there is seen a fragmentary perspective view of the heating unit 24 wherein the chamber-forming walls 30 thereof include a plurality of downwardly directed side members 31 and 32 and a roof portion 33. It will be seen that the downwardly directed sides 31 and 32 are fabricated of reinforced sheet material to form a strong structure, and one which can withstand substantial amounts of heat.

Mounted on top of the roof 33 is an air fuel mixture distribution chamber 34 which is in fluid communication with a pair of diametrically opposed longitudinal

3,874,366 input manifold members 36 and 37, as best seen in FIG. 3. The main input manifold sections 36 and 37 teed a plurality of transverse feed manifolds, here being collectively designated by reference numerals 36« and 37« as best seen in FIG. 3. Located at strategic points along each of the transverse manifold members 36« and 37« is a discrete heating unit 39 which extends downwardly within a heating chamber 40, as best seen in FIGS. 4 and 5.

In the embodiment disclosed herein the heating units 39 each are provided with a radiant heating element 41, which preferably are formed ot an Inconel material which is a nickel base, heat-and-oxidization-resistant material having approximately 13% chromium, 6% iron, and small amounts of manganese, silicon, and copper. However, it will be understood that other radiant heating clement material may be utilized in the heating apparatus of this invention.

The air fuel mixture from the chamber 34 is delivered laterally to the longitudinal chamber 36, and therefrom through openings 42 into mating openings 43 to feed the air fuel mixture into the transversely disposed distributing channels 36« and 37«. The communication between the chamber 34 and the chambers 36 and 37 is achieved through a side opening such as the opening 44 communicating the chambers 34 and 36. The chamber 34 is supplied with an air-fuel mixture inlet 35 which is coupled to the air-fuel supply by suitable flange means as seen in FIG. 3. Located within the heating chamber 40 is an upper and peripheral liner member 46 which may be formed ot refractory ceramic material to aid in producing radiant heating to be directed dow nwardly from the heating chamber onto the surface of pavement 12 being treated.

Referring once again to FIGS. 1 and 2 the heating apparatus 24 and 26 arc provided with horizontally disposed exhaust manifold members 50 and 51. While only a single exhaust manifold member is illustrated in FIGS. 1 and 2, it can be seen that FIG. 3 illustrates that each of the heating chambers of this invention are provided with a pair of spaced apart exhaust manifolds extending forwardly of the heating chamber and positioned near the side or lateral periphery thereof.

In FIG. 3, the exhaust manifold 50 is separately designated by reference numerals 50« and 506. Most advantageously. the configuration and orientation ot the horizontally disposed exhaust manifold members 50« and 50/&gt; provide means for conducting the exhaust gases and products of combustion forwardly of the heating chamber and dispensing these heated gases onto the surface of the pavement being treated. This is best seen in FIG. 4 which illustrates that the direction of travel of the hot gases and products of combustion are upwardly. as indicated by the arrowed lines, through aperture means such as a plurality of spaced apart aligned tube members 52. These hot gases then enter the exhaust manifold 50, by entering a hot-gas passage chamber 54. The manifold 50 is divided into two passages, the hot-gas passage chamber 54 and a forced-air passage chamber 56 which, in turn, communicates with the hot-gas passage chamber 54 by means ot a plurality of angularly downwardly disposed flute members 58 formed in a baffle member 53. These downwardly disposed flute members provide air How in the direction from the closed end 60 of the manifold 50 toward the exhaust outlet end 62.

Forced air is delivered to the manifold 50 by means of an inlet port 64. which may be connected to any suitable supply of forced air, as for example, a squirrel cage blower, or the like. The forced air travels through the 5 air passage chamber 56 and enters the hot-gas passage chamber 46 gradually as a result of the narrowing action provided by the baffle member 53.

The horizontally disposed exhaust manifold members 50 have downwardly turned, outw ardly flared end por10 tions 66 which lead into the exhaust outlet openings 62. As best seen in FIG. 2 the outwardly flared configuration of the horizontally disposed exhaust member 50 is fashioned so as to project hot gases downwardly upon the road surface as close to the lateral edge ot the heat15 ing apparatus as possible. This supplements heating ot the entire surface area beneath the heating apparatus by preheating difficult to heat edges. Furthermore, by so dispensing the hot gases and products of combustion within the heating chamber 40 by means ot the hori20 zontally disposed exhaust heating manifold, the disadvantage of vertical exhaust stacks is substantially completely eliminated. This exhaust arrangement will in no way interfere with overhead obstacles such as branches from trees, or power lines, or the like. Therefore, not 25 only does the unique and novel horizontal exhaust system of this invention improve the general heating characteristics of the heating apparatus by preheating the forward portion of the pavement as a heating apparatus moves in a given direction, but it also provides means 3&lt;&gt; for preventing damage to overhead obstacles.

The specific configuration of the horizontally disposed heating apparatus is now discussed. A U-shaped elongated channel member 70 is positioned upon the roof portion 33 and in registry with a holding member 33 71 which, in turn, includes apertures to fit over the top portion of the tubes 52. There may be provided collar means 72 located about each of the tubes 52 to provide substantial amounts of metal for welding the structure together.

⁴⁽¹ The top wall portion of the horizontally disposed exhaust heating member 50 is formed by a downwardly turned U-shaped member 74 which has the side portions thereof overlapping outwardly of the upward leg portions of the U-shaped member 70. This structure ⁴⁵ can then be cither secured together by a plurality of equally spaced apart rivets or screws, or it may be welded together as desired. To facilitate fabrication of the horizontally disposed exhaust manifold, the baffle member 53 is also formed as a U-shaped member, in the cross-section, as seen in FIG. 5, and has the upwardly turned leg portions thereof secured to the inner walls of the upwardly turned leg portions of the Ushaped member 70. The baffle member can then be secured in place by rivets, screws, or welding, as desired.

The specific embodiment disclosed herein has the baffle member 53 oriented so that it divides the two chambers in a manner progressively changing in crosssection, as best seen in FIG. 4. At the closed end 60. the chamber is divided so that the hot-gas passage 54 constitutes for a cross-sectional area in the order of about between 50% and 75%, and preferably in the order of about 62½%. On the other hand, the cold-air passage 56 accounts for a cross-sectional area ot about in the order of 25% and 50%, and preferably in the order rtf about 38½% . Therefore, with a total height of 8 inches of the exhaust manifold the hot-gas chamber 54. at the closed end 60, will have a height of approximately 3

3,874,366 inches, while the cold-air passage 56 will have a height of approximately 5 inches. On the other hand, the range of dimensions at the forward end of the horizontally disposed exhaust manifold 50, in the vicinity of the dot-dash lines 76 has the hot-gas passage chamber 54 providing a cross-sectional area constituting approximately 65% to 859; of the area, preferably being in the order of about 75% of the area, and the cold-air passage 56 providing a cross-sectional area of about between 15% and 35% of the cross-sectional area, preferably being in the order of about 25%. Therefore, with a total height of 8 inches along the extent of the exhaust manifold the hot-gas passage chamber 54, in the region of the vertical line 76, has a height of approximately 6 inches while the cold air passage chamber 56 has a height of about 2 inches.

Referring now to FIG. 3 the flared end portion 66 leading into the exhaust opening 62 is substantially 75% greater in width than the width of the horizontally disposed exhaust manifold. For example, an exhaust manifold having a width of 8 inches along the parallel side walls thereof will then have a width of approximately 14 inches at the maximum extent of the flared end 66.

While a single specific embodiment of this invention is here illustrated, it will be understood that a multitude of variations and modifications may he effected without departing from the spirit and scope of the novel concepts disclosed and claimed herein.