Pipes and tubular conduits – With flow regulators and/or baffles – Heat transfer
Reexamination Certificate
2000-12-08
2001-11-27
Hook, James (Department: 3752)
Pipes and tubular conduits
With flow regulators and/or baffles
Heat transfer
C138S106000, C165S179000, C165S183000
Reexamination Certificate
active
06321792
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a flow conduit and surface enlarging means for cooling the fluid contained in the flow conduit. The invention further relates to a fuel pipe with one or more angulations for establishing flow communication between a tank and a motor installation in a vehicle, and a method for the manufacture thereof.
The fuel system in a vehicle serves to supply fuel to the motor from a tank installed in that vehicle. The fuel is pumped into an advance conduit leading to the motor. The fuel which is not consumed in the motor is extremely hot and is pumped back into the tank via a return conduit.
U.S. Pat. No. 4,479,359 teaches a conduit for heating cryogenic fluid. In particular, a heating tube comprises a cylindrical tube having both internal and external fins. The external fins comprise fins extending upwardly from the cylindrical tube. Thus, dirt may accumulate between these fins so that the heat exchanging characteristics will be reduced or vary depending on the amount of dirt accumulated in the spaces between the fins.
WO 94/23257 discloses a heat exchanger that has among its objects to cool fuel in the fuel system of a vehicle. The cooler in this arrangement has been inserted between two conduits in the return conduit. However, this cooler is very space-intensive, and in that cooler a very large loss of pressure occurs in the return conduit which means that a large pumping capacity is required to return the amount of fuel in the return conduit to the tank.
EP-0 807 756 teaches a fuel system for a vehicle wherein a tubular section is inserted. The tubular section has axially oriented cooling ribs for cooling the fuel in the advance and return conduits in the fuel system. At each of its ends, this tubular section is connected by means of tubes to the motor and tank, respectively. The tubular section comprises two parallel flow conduits and is provided with cooling ribs that allow the fuel to be cooled in a simple manner by the streams of air underneath the bottom of the vehicle.
The fuel system according to EP-0 807 756 eliminates the drawbacks in connection with pressure drops and large pumping capacity, and common tubing underneath the bottom is also utilized which saves space compared to previous designs. However, dirt may accumulate on this cooling profile that may deposit on top of and between the cooling ribs and thus reduce the cooling effect or even have an insulating effect on the profile tubing. Moreover, this known type of fuel pipe comprises mechanical joints, such as soldered joints between fuel tubing, connector tubing and cooler tubing. Such joints present: a risk of leak. This risk is greatly increased when the fuel is to be advanced in the fuel pipe under pressure. It is therefore desirable to be able to manufacture a fuel system with a minimum of joints, especially welded joints and soldered joints, in order to hereby reduce the risk of leaks occurring due to a weak joint.
In case of motors based on recently developed technology, a marked increase in the pressure and temperature of the fuel may occur. The temperature may become extremely elevated which gives rise to problems in connection with fuel tanks made of plastics and/or components in connection therewith. Likewise the fuel, such as the diesel oil, may react chemically with the plastic parts of the tank whereby the tank as well as the fuel can suffer damage. Moreover the fuel can also suffer damage such as a consequence of boiling at the elevated temperatures. In the light of this it is, in connection with such novel motor installations, of the utmost importance to cool the fuel effectively, and many producers thus require that the temperature of the fuel must be kept below a suitably low temperature.
SUMMARY OF THE INVENTION
In view of these problems, it is the object of the invention to provide a flow conduit that remedies the above-mentioned drawbacks, and whereby the stipulated requirements to cooling can be complied with.
The invention consists of a flow conduit of the kind described above wherein the surface-enlarging means comprise cooling blades that extend outwards and/or downwards from surface parts of the flow conduit. The flow conduit features an upwardly facing surface portion which is exclusively planar and/or convex.
With a flow conduit according to the invention for cooling fuel, adequate cooling of the fuel is obtained in all conditions. The particular configurations of the flow conduit and the surface-enlarging means prevent accumulation of dirt in the spaces between the cooling blades, or on the upwardly facing surface part of the profile, since dirt, if any, will drop out of the spaces and the upwardly facing surface portion by itself. The surface-enlarging means on the flow conduit are thus self-cleaning.
The configuration wherein the cooling blades of the flow conduit feature a bendable base section and a section provided with cooling fins allows the profile to be extruded with a relatively flat contour following so that the cooling blades can be bent downwards to become self-cleaning. Thus, in the preferred embodiment of the profile according to the invention, the cooling fins in the outer section are inclined relative to the cooling blades in such a manner that the cooling fins point away from the tubular section. Moreover, two cooling blades can be provided that are, at their base sections, bendable in such a manner that the cooling fins exhibit downwardly inclining surfaces. Thus, the self-cleaning function is ensured on both sides of the cooling blades, the cooling fins on both sides of the cooling blades all featuring a downwardly inclining surface.
The flow conduit according to the invention is in one embodiment an extruded aluminum profile. Aluminum is extremely heat-conductive and easily deformable which means that the profile according to this embodiment is uncomplicated to manufacture by extrusion and the material thus chosen also yields an adequate cooling effect. In one embodiment of the flow conduit, it is made with internal cooling fins. Thus, a further cooling of the flow medium in the conduit is obtained.
In a further embodiment, the flow conduit consists of several interconnected elements comprising an internal tubular element and an external cooling element with cooling blades. The outer surface of the tubular elements abuts on surface portions of the cooling element. Thus, the cooling element with the cooling blades can be mounted subsequently on those sections of the flow conduit where it is most convenient. For instance, the cooling element can be soldered onto the surface of the flow conduit to provide adequate thermal connection between the flow conduit and the cooling element. Also, attachment by mechanical deformation may result in an adequate thermal connection between the elements and is therefor a further option.
Additionally, the invention relates to a fuel pipe configured as a flow conduit according to the first aspect of this invention wherein the flow conduit exhibits one or more areas of angulation or attachment. The cooling blades have been removed, and essentially, the flow conduit thus merely consists of a tubular element.
The fuel pipe according to this aspect of the invention is configured in one piece and thus it does not feature soldered joints, welded joints or the like joints that weaken the strength of the flow conduit. Thus, the risk of leaks is considerably reduced.
In a preferred embodiment of the fuel pipe according to the invention, the cooling blades have been cut off or in other way removed from the tubular element at least at the one end of the profile, and the tubular element is configured with coupling means for coupling to a tank or motor installation. Thus, it is possible to configure a coupling stud in the tubular element at the end of the conduit. This means that the number of joints in connection with the conduit is further reduced, because mounting of coupling means on the fuel pipe no longer is necessary when a fuel pipe having this embodiment of the invention is used.
In
Boysen Karl
Johnsen Peter
Køhling Peter N.
Von Huth Smith Ulf
Hook James
Norsk Hydro ASA
Wenderoth , Lind & Ponack, L.L.P.
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