Fluid handling – With heating or cooling of the system – Air heated or cooled
Reexamination Certificate
2000-03-20
2001-06-26
Chambers, A. Michael (Department: 3753)
Fluid handling
With heating or cooling of the system
Air heated or cooled
C123S541000, C123S041310
Reexamination Certificate
active
06250328
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for supplying an internal combustion engine of a motor vehicle with fuel having a feed line which leads from a fuel tank to the internal combustion engine and having a return line for the purpose of returning the fuel to the fuel tank and having a cooling device for cooling the fuel fed back into the fuel tank.
Such devices are often used in today's motor vehicles with diesel internal combustion engines and are known in practice. Here, the cooling device has a radiator which is mounted in the return line and is exposed to the relative wind of the motor vehicle. Cooling the fuel serves to keep the temperature in the fuel tank below an envisaged value. The maximum temperature which should not be exceeded in the fuel tank depends essentially on the material of the fuel tank and, in current plastic fuel tanks, is about 70° C. Cooling of the fuel in the return line is necessary in the case of systems for internal combustion engines referred to as common-rail systems, for example, because here the fuel fed back via the return line is heated particularly strongly by the internal combustion engine.
The disadvantage with the known device is that the radiator, which has to be mounted in the relative wind, makes it very complex in construction and costly to manufacture.
The problem underlying the invention is to configure a device of the type stated at the outset in such a way that its construction is as simple as possible in terms of design and it can be produced at a reasonable cost.
BRIEF DESCRIPTION OF THE INVENTION
According to the invention, this problem is solved by the fact that the return line is manufactured from a material of high thermal conductivity and the cooling device has means for guiding a cooling medium along at least a subsection of the return line.
By virtue of this configuration, the fuel can release heat via the wall of the return line. As a result, there is no need for the involved process of mounting components in the return line to cool the fuel. The device according to the invention is therefore of particularly simple construction and can be produced at reasonable cost. Since the temperature of the fuel within the return line differs greatly from the surroundings, ambient air of the motor vehicle is generally sufficient as the cooling medium.
As in the known device, the medium which cools the fuel in the return line could be the relative wind of the motor vehicle, for example. However, this does not ensure adequate cooling of the fuel, particularly when the motor vehicle is traveling uphill or in congested traffic. According to an advantageous development of the invention, the fuel in the return line can be cooled reliably to an envisaged temperature level if the cooling device has a fan, which conveys the air along the return line, or an intake unit for combustion air. The cooling of the return line with combustion air drawn in by the internal combustion engine furthermore has the advantage that fuel which escapes due to leaks or permeation from the device according to the invention is fed to the internal combustion engine.
According to another advantageous development of the invention, the fuel conveyed in the return line is cooled in a particularly intensive manner if the cooling device has a ventilation duct for accommodating the return line and for guiding the cooling air along the return line.
According to another advantageous development of the invention, the cooling device does not require the additional installation of a fan if the ventilation duct is continued as far as an intake side of a cooling fan of a liquid cooling system of the internal combustion engine.
The device according to the invention can be installed in a particularly simple manner in the motor vehicle if the feed line is arranged within the ventilation duct. This makes it possible to connect the feed line and the return line to one another first and then to secure them together in the ventilation duct. Since the fuel conveyed in the feed line is at a lower temperature than that in the return line, this configuration cannot contribute to unnecessary heating of the fuel fed back into the fuel tank.
According to another advantageous development of the invention, it is a simple matter to keep the fuel tank at an envisaged temperature level if the ventilation duct encloses at least a partial region of the fuel tank with a clearance. It is sufficient here if the bottom region of the fuel tank is enclosed since, particularly when the fuel tank is almost empty, the fuel fed back by the return line has a great effect on the temperature in the fuel tank.
According to another advantageous development of the invention, the return line has a particularly large heat-emitting surface if cooling elements are arranged on the return line.
According to another advantageous development of the invention, guide elements for guiding cooling air onto the return line contribute to a further improvement in heat transfer from the return line to the cooling medium.
The design configuration of the device according to the invention is particularly simple if the feed line is manufactured from a material of high thermal conductivity, and if the return line and the feed line rest against one another. Since the fuel in the return line is at a higher temperature and has a smaller volume flow than that in the feed line, it is cooled in a particularly reliable manner as a result. This configuration can keep the temperature in the fuel tank low either alone or together with the cooling air guided along the return line. A further advantage of this configuration consists in that the internal combustion engine receives preheated fuel in the case of a cold start.
According to another advantageous development of the invention, the installation of the feed line and the return line in the motor vehicle is particularly simple if the feed line and the return line have a subsection with a common partition wall of high thermal conductivity.
The device according to the invention requires a particularly low outlay on construction if the return line and the feed line are intertwined.
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Distelhoff Markus
Eck Karl
Frohlich Winfried
Keller Dieter
Klöker Justus
Chambers A. Michael
Mannesmann VDO AG
Mayor Brown & Platt
McShane Thomas L.
Speer Richard A.
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