Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
2000-10-25
2002-10-08
Mancene, Gene (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C123S041010, C165S052000, C060S617000
Reexamination Certificate
active
06460520
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to components for internal combustion engines particularly, although not exclusively, to a tubular component for transferring exhaust gases between an exhaust manifold and an inlet manifold where exhaust gases are cooled during transfer between the exhaust manifold and the inlet manifold.
BACKGROUND TO THE INVENTION
It is known in the prior art to use exhaust gas re-circulation systems as part of an internal combustion engine. An exhaust gas re-circulation system transfers exhaust gas from an exhaust manifold, returning the exhaust gas to an inlet manifold on the engine block allowing the returned gas to re-enter a combustion chamber. The purpose of an exhaust gas re-circulation system is to reduce formation of NOX during the combustion process. A cooled exhaust gas re-circulation system achieves this by taking exhaust gas from an exhaust manifold, and cooling the gas during transfer between the exhaust manifold and an inlet manifold thus giving a dense charge of gas returned to the inlet manifold for introduction into an inlet charge prior to combustion.
Prior art exhaust gas re-circulation systems incorporate a multi-component system including a plurality of tubular elements including a cooling element. Commonly the cooling element is substantially straight and hence difficult to package around the internal combustion engine.
FIG. 1
herein illustrates a prior art exhaust gas re-circulation system. This system incorporates a first tubular section
100
attached to an exhaust manifold by fastening means at a first end
107
and a second tubular section
111
attached to an inlet manifold at a second end
108
. Referring to
FIG. 1
, exhaust gases entering tube
100
at first end
107
, the direction of exhaust gas flow being indicated by arrows, are transferred to a cooler
102
. This may occur through one or a plurality of bends
101
in tube
100
of the exhaust gas re-circulation system. Within the exhaust gas re-circulation system there exists a cooler section
102
. This is a separate component joined to the first and second tubes
100
,
111
at points
109
and
110
. Cooler
102
consists of a heat exchanger housing a plurality of tubes
105
extending the length of cooler
102
. The plurality of tubes
105
are illustrated in FIG.
1
(B) which shows a section of cooler
102
. Each tube
105
has a diameter in the region of 6 mm. The Cooler
102
may contain an average of
30
such tubes although in some instances this amount may be as great as
60
. Cooler
102
further comprises an inlet
104
and outlet
103
which permit coolant medium to enter a chamber surrounding the plurality of smaller tubes
105
, thus permitting heat exchange between the gasses passing through the tubes
105
and the surrounding coolant medium. Inlet
104
and outlet
103
are further connected to pipework and fittings of the internal combustion engine cooling system. Such a system commonly incorporates a radiator. Coolant medium within the cooler
102
is not permitted to enter the first or second tubes
100
,
111
, the coolant medium being restricted to the length of the cooler
102
.
In prior art exhaust gas re-circulation systems employing a cooler
102
there is a significant loss of efficiency due to blocking of tubes
105
by sooty deposits, commonly being acidic deposits, which are formed in the tubes
105
due to condensation of partially or non-combusted fuel. Diesel fuel, includes sulphur based compounds which can form highly acidic compounds on partial combustion. Such deposits may therefore corrode and block the tubes
105
. Such corrosion and blockage means that the performance of the cooler
102
deteriorates significantly over time. A considerable loss in efficiency is seen within the first five hours of operation of such a prior art exhaust gas re-circulation system with up to 20% reduction in efficiency occurring in this period due to coating and/or blockage of the tubes
105
. Therefore, prior art exhaust gas re-circulation systems lose efficiency and begin to corrode on first use. Use of higher grade materials to counter corrosion is hampered by the cost of the solutions when applied to a prior art multi-tube design.
A further disadvantage of prior art exhaust gas re-circulation systems is that cooler
102
is commonly of the order of 100 mm to 300 mm in length. As the levels of required emissions from internal combustion engines, particularly those used in cars, decrease and as the need for employing such systems on small cars to ensure low levels of emissions increases manufacturers are commonly finding that there is not enough space to conveniently package prior art coolers which require significant room in which to fit the long, straight cooler
102
.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a single piece component for use as an exhaust gas re-circulation system for transferring exhaust gases from an exhaust manifold to an inlet manifold of an internal combustion engine, whilst cooling the exhaust gases during transfer.
A second object of the present invention is to provide an exhaust gas re-circulation system for an internal combustion engine including a self-cleaning mechanism to prevent blockage of tubes which are transferring exhaust gases.
A third object of the present invention is to provide an exhaust gas re-circulation system where heat exchanged between exhaust gases and a coolant medium, occurring indirectly through a tubular wall, can take place substantially along the entire length of said exhaust gas re-circulation system.
A fourth object of the present invention provides for an exhaust gas re-circulation system with a decreased number of tubular members required to provide for heat exchange with a surrounding coolant medium, whilst providing an effective surface area for heat exchange which provides for at least comparable cooling of exhaust gases when compared to prior art coolers.
A fifth object of the present invention is to provide a low weight, low cost exhaust gas re-circulation system for an internal combustion engine.
According to a first aspect of the present invention there is provided a component for transferring gases between an inlet port and an outlet port of an internal combustion engine said component characterized by comprising:
a substantially tubular outer member having a first end and a second end, and an outer tubular wall extending between said first and second ends; and
a plurality of substantially tubular inner members housed in said first substantially tubular outer member, wherein said second substantially tubular inner members are corrugated along at least part of their length.
Preferably said plurality of substantially tubular inner members extend substantially an entire length of said substantially tubular outer member between said first and said second ends.
Said plurality of substantially tubular inner members may comprise a plurality of tubular sections, each following a curved path.
Preferably said first substantially tubular outer member is corrugated throughout at least one portion.
Preferably said first substantially tubular outer member contains apertures suitable for inlet and outlet of a coolant medium.
Preferably said first and second ends of said outer tubular member are substantially blocked in order to retain coolant medium within said first substantially tubular outer member, save for apertures remaining to permit gas flow into each of said plurality of substantially tubular inner members.
Said plurality of substantially tubular inner members may be mounted through at least one spacer maintaining said substantially tubular inner members at substantially fixed position s relative to each other.
Said outer tubular member may be substantially bent to a required shape.
In one embodiment, said substantially tubular outer member is manufactured from metal tubing with a wall thickness in the region of 0.3 to 0.5 mm; and
said substantially tubular inner members are manufactured from metal tubing with a wall thickness in the regi
Castro Arnold
Dick and Harris
Mancene Gene
Senior Investments AG
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