Manhole Ventilating And Heating System

Abstract

An apparatus for providing a continuous flow of air into manholes below the ground level such as those used for servicing underground communication facilities. A hollow, toroidal-shaped member adapted to fit within a manhole entrance to the hole forms an annular shaped chamber with an annular outlet below the ground level. Air under pressure is provided to the toroidal member and is deflected downwardly by internal baffles into the hole. The incoming air may be heated either by a portable heat source or by conduit coils within the chamber that are supplied with heated fluid or gas from a truck or the like.

Description

This invention relates to an apparatus for supplying fresh air which may be heated to ground holes or structural cavities through a manhole entrance.

Such ground holes or cavities are required to provide servicing facilities for underground communication and electrical power systems. In most cities large numbers of such cavities are located in the streets and access to them is by a manhole entrance having the well-known removable cover. The job of servicing underground telephone or power systems in such cavities requires a workman to remain in them for substantial periods of time. A problem which arose in carrying out these servicing tasks was that of properly ventilating the cavity with a continuous supply of fresh air and an additional problem arose in providing heated air during inclement weather conditions. Previous attempts to solve these problems were generally too costly in time and labor as well as inefficient. For example, one approach was merely to connect a large conduit to an auxiliary heating unit and place its outlet end through the manhole into the ground cavity. However, this restricted the access area available in the manhole and in addition, the circulation and distribution of air within the cavity was unsatisfactory. In such arrangements the air was heated, when necessary, by auxiliary heaters which were generally expensive and inefficient.

A general object of the present invention is to provide an apparatus for supplying fresh air to a ground cavity through a manhole that will solve the aforesaid problems.

Another object of the present invention is to provide an apparatus for supplying a continuous flow of fresh air to a ground cavity that will (1) reduce the size of the access opening to the cavity be a relatively small amount and thereby facilitate the easy passage of persons and equipment into and out of the cavity and (2) cause the air to circulate within the cavity so as to constantly purge it of stale air.

Another object of the present invention is to provide an apparatus for supplying a continuous flow of warmed, fresh air to a ground cavity that can utilize as a source of heat an internal combustion engine in a truck or the like that can be located near the manhole.

Another object of the present invention is to provide an apparatus for supplying a continuous flow of warmed, fresh air to a ground cavity that will heat fresh air to the temperature desired and distribute it within the cavity in a manner that causes the air within the cavity to be constantly moved and replaced.

Another object of the present invention is to provide an apparatus for supplying a continuous flow of fresh air to a ground cavity that is particularly well adapted for ease and economy of manufacturing.

Another object of the present invention is to provide an apparatus for supplying a continuous flow of fresh air to a ground cavity that will provide an annular wall with a fluid tight seal around the manhole entrance to prevent the influx of any fluid or other materials from the surrounding street surface into the cavity.

The aforesaid objects are accomplished by a toroidal-shaped housing formed by an inner wall member and an outer wall member connected together at their upper ends. The outer wall member is provided with a sealing ring that cooperates with the manhole covering ring to provide a fluidtight seal and the inner wall member is spaced radially inwardly from the outer wall member and extends downwardly into the cavity, thereby forming an annular outlet for the housing. Baffle members are provided within the toroidal housing to direct air downwardly within the housing toward its annular outlet. The lower skirt of the inner wall forms an annular deflector that causes the air leaving the annular outlet to assume a circulating flow path within the cavity. Fresh air is supplied to the housing through an inlet in its outer wall member. In one embodiment of the present invention the fresh air is heated within the housing as it passes over the coils of a heating conduit mounted within the housing. In other embodiments a unique heat-exchanger unit is provided in a separate housing which may be located outside or attached to the toroidal housing. The source of heat for the heating conduit may be the cooling or exhaust system of a conventional internal combustion engine, such as a truck that can be conveniently parked near the manhole entrance to the cavity being used.

Other objects, advantages and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view in elevation and in section showing one form of apparatus embodying the principles of the present invention;

FIG. 2 is a view in elevation and in section of another form of apparatus according to my invention;

FIG. 2a is an enlarged fragmentary view in elevation and in section showing an outer edge portion of my apparatus that is sealed around the manhole;

FIG. 3 is a schematic view in elevation and in section of another form of my apparatus utilizing an internal heating conduit;

FIG. 4 is a view in elevation and in section of yet another form of my apparatus;

FIG. 4a is a top view of the apparatus shown in FIG. 4;

FIG. 5 is a schematic plan view showing one arrangement for using my apparatus with an engine exhaust system as a heat source;

FIG. 6 is a schematic plan view showing a modified form of the system of FIG. 5;

FIG. 7 is a schematic plan view showing my apparatus used in combination with an engine cooling system; and

FIG. 8 is a schematic plan view showing another form of my apparatus using electrical heating coils.

Referring to the drawing, FIG. 1 shows an apparatus 10 according to the principles of my invention as it appears when installed in the manhole entrance of a cavity 12. The latter could be a ground cavity that normally contains the cable connections for an underground communication or power system or it could be any other restricted enclosure such as a compartment of a ship. For such ground cavities the manhole entrance is usually comprised of a circular metal ring 14 that is set in the surrounding concrete or asphalt surface. This ring has an L-shaped cross section forming a vertical, annular shoulder 16 and a horizontal shoulder 18 that supports the edge of a conventional circular manhole cover. The apparatus 10 includes a housing 20 having a toroidal shape which is adaptable to fit within the aforesaid manhole ring. This housing may be made from any suitable sheet material such as metal or reinforced plastic and generally it is comprised of an outer vertical wall member 22 that extends upwardly and then inwardly to connect with an inner wall member 24. As shown in FIG. 1, these inner and outer wall members may be connected at their upper ends by an integral portion 26 having an inverted U-shaped cross section. However, this section could also be in the form of a flat end piece that is connected to the wall members by some means such as welding.

The outer cylindrical wall member preferably has a diameter slightly less than that of the diameter of the vertical shoulder 16 of the ring member 14. As shown in FIG. 2a, this outer wall member is bent near its lower end to form an annular recess 28 within which an elastomeric O-ring 30 can be seated to form a sealing means. Just below the recess the outer wall member 22 extends inwardly and then downwardly to form a lower skirt portion 32 that fits just inside the inner edge of the ring forming the manhole entrance. When the housing is placed within the manhole entrance, the outer wall member 22 rests on the horizontal shoulder 18 of the ring 14 and the sealing ring 30 wedges tightly against the vertical shoulder 16, thereby forming a fluidtight seal that prevents any water or air from flowing over the surrounding surface into the manhole entrance. The inner wall member 24 is longer than the outer wall member 22 and when installed extends well inside the manhole entrance to the cavity. At its lower end the inner wall member has a skirt portion 34 that diverges outwardly to deflect incoming warm air radially outwardly as it flows into the cavity.

In order to assist the flow of air through the deflector housing 20 a series of baffle members 36 are preferably connected between its inner and outer wall members. These baffle members may be in the form of circumferentially spaced apart thin metal strips whose side edges may be welded or riveted to the inner surfaces of the wall members. As shown, these baffle members curve gradually downwardly while following the curvature of the wall members. Thus, air forced into the housing tangentially flows in a circumferential direction and then downwardly, so that as it flows out of the housing it is not only deflected outwardly but also has a circulatory motion as it passes into the cavity. This provides a beneficial effect because, as indicated roughly by the arrows in FIG. 1, the air in the cavity is constantly circulated and the stale air is forced out the central opening of the housing 20.

To provide heated fresh air for the cavity at the lower annular outlet of the housing 20, the air can be heated either before it enters the housing or after. In FIG. 1, the general arrangement of providing preheated air to the housing is shown schematically. The fresh air is supplied to a suitable heater unit 38 and thence to a fan or blower 40 that feeds the air into the housing so that, as previously described, the warm air will circulate and be deflected downwardly by the baffle 36. If no heat is required the unit 38 is merely removed from the fan.

In the embodiment of FIG. 2, the heater unit or heat exchanger 38 as shown schematically comprises a housing 42 having a closed upper end and mounted on a base 44 that surrounds a series of vertically spaced-apart conduit coils 46. A hot fluid is fed into one end of the coils and is exhausted from its other end at an outlet through he housing 42. The lower edge of the housing 42 is spaced above the base 44 so that an annular inlet for surrounding air is provided. Extending upwardly from the base through the coils is a central upright conduit 48 that is open at its upper end just above the coils. At its lower end the conduit 48 extends to the blower 40 which draws air into the housing 42 and forces it into the deflector housing 20. The heat exchanger 38 is shown as being merely one form of such a device and it is apparent that other heaters and exchangers could be used within the scope of the invention.

As shown in FIGS. 4 and 4a, the blower or fan 40 may be mounted within a side portion 49 of the housing 20 which directs the air from the fan tangentially into the housing. The fan is mounted for rotation in a horizontal plane and when heated air is required a heat exchanger 38 such as shown in FIG. 2 is merely attached to the inlet ring to the fan on the side portion 49. The heat-supplying fluid may be supplied as previously described.

In FIG. 5, a somewhat different apparatus is shown schematically wherein a heat exchanger 38a utilizes the exhaust from an internal combustion engine such as on a truck 50 to provide the means for preheating air before forcing it into the deflector housing 20. The internal details of the heat exchanger are not shown since its design can be established by application of well-known engineering principles. Essentially, an inlet conduit 52 connected to the truck exhaust pipe 54 provides the hot gases to the heat exchanger. Within the exchanger, suitable fluid paths are provided to extract heat from the gases, which are then removed via an outlet 56 to the atmosphere. An inlet 58 supplies fresh air to the exchanger wherein this air is heated and then supplied to the blower 40 whose outlet 60 is connected to the deflector housing 20, as previously described.

The heat exchanger 38a may be a portable unit that can easily be moved into location near the manhole being serviced, with its inlet conduit 52 being provided with a suitable adapter to facilitate connection to a conventional exhaust pipe on the truck. Or the heat exchanger may be in the same general form as the changer 38 and thus usable in either the arrangement of FIG. 2 or of FIG. 4.

In another arrangement of my invention, shown in FIG. 6, a heat exchanger 38b is installed directly on a truck 50. Here, the heat exchanger inlet conduit 52b is connected to a two-position valve 62 in the truck exhaust pipe which can be set to divert hot exhaust gases into the heat exchanger when desired. The heat exchanger takes in ambient fresh air, as previously described, and supplies it to a blower 40 which furnishes the air direct to the deflector housing 20.

As shown in FIGS. 3 and 7, it may be advantageous in some instances to provide conduit coils 64 directly within a toroidal-shaped deflector housing 20a, thereby eliminating the need for an external heat exchanger or heat source. In this arrangement a hot fluid is supplied to one inlet end 65 of the conduit coils 64 and is circulated therein before being removed from its outlet end. In the arrangement of the heat-supplying fluid is the engine-cooling liquid from the operating engine 66 of a truck 50 that can be located near the manhole being serviced. The inlet and outlet ends of the conduit coils 64 which extend outside the deflector wall may be connected by conduits 68 and 70 to the engine to circulate hot fluid from its cooling system. Fresh air is again supplied by a blower 40 which may be located near or at the inlet to the deflector housing 20a. The air blown into the deflector housing is warmed as it flows over the conduit coils 64 and then downwardly into the manhole.

In yet another embodiment of my manhole-heating system, shown schematically in FIG. 8, heating coils 72 are provided of electric resistance-heating type. The electricity for such coils can be provided through a electrical conduit 74 connected to the generator or battery 76 of a truck 50 or to some other convenient electrical power source near the manhole. Here again fresh air is supplied to the deflector housing 20b by a blower 40 connected thereto which forces air over the coils and down into the manhole cavity.

All of the aforesaid embodiments of the present invention provide an efficient, economical and highly effective solution to the problem of supplying fresh and heated air to a manhole cavity. Upon removal of the conventional manhole cover from its ring 14, the deflector housing 20 which is relatively light can be easily placed in position. Using any of the aforesaid arrangements, fresh air forced into the housing by the blower 40 is deflected downwardly and radially outwardly within the manhole cavity to cause a purging circulation that provides the required ventilation for a worker in the cavity. When heat is a requirement, it can be supplied conveniently and efficiently from sources normally available such as from the engines of service trucks or other vehicles according to the invention.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

Claims

I claim:

1. An apparatus for providing a flow of fresh air to a ground cavity through a manhole entrance thereto comprising:

a toroidal-shaped housing having an outer wall member with a larger diameter than the manhole entrance, a concentric inner wall member with a smaller diameter than the manhole entrance and means interconnecting said wall members at their upper ends to form an annular chamber, said inner wall having a lower portion that extends below said outer wall member;

means providing an inlet for fresh air in said outer wall member;

and fan means forcing air to flow through said inlet so that it exits from said chamber between the lower ends of said inner and outer wall members.

2. The apparatus ad described in claim 1 wherein said means providing an inlet comprises a projecting portion attached to the outside wall member of said housing and arranged to direct air substantially tangentially into said housing.

3. The apparatus as described in claim 1 including baffle means within said housing between said wall members for directing downwardly the air that enters through said inlet.

4. The apparatus as described in claim 1 including means for heating the fresh air that is forced to flow through said inlet.

5. The apparatus as described in claim 1 including sealing means on the outside of said outer wall member near its lower end for forming a fluidtight seal between said housing and the structure surrounding the manhole.

6. The apparatus as described in claim 3 wherein said baffle means comprise a plurality of circumferentially spaced-apart metal strips extending between said inner and outer wall members, each said strip being curved downwardly from its upper end to its lower end.

7. The apparatus as described in claim 1 wherein said inner wall has a skirt portion on its said lower portion that diverges outwardly at its lower end.

8. The apparatus as described in claim 5 wherein said sealing means comprises an annular recess in said outside wall member and an annular O-ring retained within said recess but having an outside diameter greater than that of said outside wall member.

9. The apparatus as described in claim 4 wherein said means for heating comprises a coiled conduit mounted within said housing and inlet and outlet means at the ends of said conduit extending through said outside wall member and hot-fluid supply means connected to one end of said coiled conduit.

10. An apparatus for providing a flow of heated fresh air to a ground cavity through a manhole entrance thereto comprising:

a toroidal-shaped housing forming an annular chamber with an outer wall member spaced radially outwardly from the edge of the manhole entrance;

an inner wall member spaced radially inwardly from said outer wall member and adapted to be spaced inwardly from the edge of the manhole entrance, thereby forming an annular outlet from said housing within the ground cavity below the surrounding ground level;

blower means for forcing fresh air through an inlet in said outer wall member;

and means for heating the fresh air before it exits from said annular outlet of said housing.

11. The apparatus as described in claim 10 wherein said means for heating comprises a plurality of hot-fluid passages located in the flow path of fresh air moved by said blower and hot-fluid supply means connected to said hot fluid passages.

12. The apparatus as described in claim 11 wherein said hot-fluid passages are conduit coils located within said housing between said wall members.

13. The apparatus as described in claim 10 wherein said means for heating fresh air comprises a portable heat-exchanger unit having an inlet for receiving relatively cool fresh air and an outlet for heated air connected to said inlet in said outer housing wall member; a source of hot fluid; and a series of fluid passages connected to said source of hot fluid and surrounding a passage for fresh air.

14. The apparatus as describe in claims 12 wherein said hot-fluid supply means is the water cooling system of an internal combustion engine.

15. The apparatus as described in claims 12 wherein said hot-fluid supply means includes an internal combustion engine having an exhaust pipe, a conduit interconnecting said exhaust pipe and said hot-fluid passages.

16. The apparatus as described in claim 10 wherein said means for heating comprises a series of electrical heating elements located between said wall members of said housing.