Power plants – Internal combustion engine with treatment or handling of... – By means producing a chemical reaction of a component of the...
Reexamination Certificate
1998-12-22
2001-01-30
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
By means producing a chemical reaction of a component of the...
C060S298000, C060S320000, C060S301000
Reexamination Certificate
active
06178744
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns the treatment of exhaust gases and residues produced in particular by the engines of motor vehicles.
The invention is more particularly concerned with catalytic converters that comprise a casing an entry end of which is connected to the outlet of a manifold for engine exhaust gases and residues and which houses catalyst means capable of modifying at least some of the exhaust gases and residues (the most polluting ones) and trap means capable in particular of retaining certain polluting molecules and catalytically converting them into non-polluting molecules when the environment is a reducing environment (for example when the richness of the air-fuel mixture is ideal or optimal).
BACKGROUND OF THE INVENTION
The polluting exhaust gases and residues are in particular nitrogen monoxide and hydrocarbons that have not been burned in the combustion chamber of the engine.
In prior art catalytic converters the catalyst means require high operating temperatures to operate with good efficiency. The temperature of the exhaust gases and residues is totally appropriate to this. However, the trap means, which are immediately downstream of the catalyst means, are not good at withstanding the high temperatures of the gases and residues, especially when “heavily loaded”, for example on a freeway. As a result the efficiency of the trap means is less than optimal if the temperature rises too high and tends to fall rapidly because the materials from which they are made deteriorate.
Also, the trap means have optimal efficiency over a relatively narrow range of temperatures that rarely includes the temperature of the exhaust gases and residues.
DISCUSSION OF THE INVENTION
An aim of the invention is therefore to provide a catalytic converter that is free of some or all of the drawbacks referred to above.
To this end the invention proposes a catalytic converter of the type described in the introduction in which a central part of the casing downstream of the catalyst means and upstream of the trap means houses cooling means adapted to reduce the temperature of the gases and residues upstream of the trap means below a predetermined threshold.
In this way there is no longer any risk of the temperature of the gases and residues reaching the trap means damaging the materials from which they are made.
The cooling means are preferably in the form of a heat exchanger and even more preferably in the form of a circulating fluid type cooling radiator.
A radiator of the above kind could be part of a circuit for controlling only the temperature of the gases and residues. However, it is particularly advantageous for the radiator to be connected to a circuit supplying fluid to a heating radiator of a heating and/or air conditioning installation of the vehicle. This enables recovery of heat via the fluid at the radiator of the catalytic converter, in particular for improved heating of the passenger compartment, for example in the period immediately after starting the engine.
In accordance with another feature of the invention the casing houses means downstream of the catalyst means for controlling access to at least a part of the central area housing the heat exchanger under the control of a control module and based on a test applying either to the temperature of the exhaust gases and residues upstream of the central area or to the time period between the start of the test and a predetermined time, for example starting of the engine.
In this way the temperature of the exhaust gases and residues reaching the trap means can be precisely controlled in accordance with the operating conditions of the engine so that the temperature can be maintained in a range of values substantially identical to the range for optimal functioning of the trap means.
Access control means of the above kind can be implemented in the form of shut-off means capable of shutting off at least part of the heat exchanger. A valve such as a butterfly valve could be used, for example.
The shut-off means can be adapted to shut off all of the heat exchanger.
In a preferred embodiment the heat exchanger has a cross-section with a smaller area than the inside cross-section of the casing so that a passage having a cross-section equal to the difference between the cross-sections of the exchanger and the casing allows direct communication between areas on respective opposite sides of the central area in the casing.
Accordingly, some of the modified gases and residues can if necessary reach the trap means directly without being cooled.
In this embodiment the shut-off means are preferably adapted to control access only to the aforementioned passage under the control of the control means and the passage is preferably formed in the heat exchanger, for example in its central area.
In accordance with another feature of the invention the casing has an empty area between the catalyst means and the cooling means for distributing the modified gases and residues. Another area of the same type can be provided between the trap means and the cooling means. This enables good distribution of the modified and/or cooled gases and residues for a more uniform temperature.
The invention applies in particular to catalyst means and trap means including agents for oxidizing the exhaust gases and residues if their respective compositions are not equal to chosen values, for example if the richness of the air/fuel mixture is not optimal, and at least to trap means that include agents for reducing the oxidized gases and residues and then converting them into non-polluting emissions if their respective compositions are substantially equal to said chosen values, for example if the richness of the air/fuel mixture is optimal.
The following description given by way of example refers to the accompanying drawings.
REFERENCES:
patent: 3228746 (1966-01-01), Howk et al.
patent: 3757521 (1973-09-01), Tourtellotte et al.
patent: 3842600 (1974-10-01), Nakajima et al.
patent: 4318894 (1982-03-01), Hensel et al.
patent: 5184462 (1993-02-01), Schatz
patent: 5277026 (1994-01-01), Boll et al.
patent: 5477676 (1995-12-01), Benson et al.
patent: 5787706 (1998-08-01), Smedler et al.
patent: 5845485 (1998-12-01), Murphy et al.
patent: 5983628 (1999-11-01), Borroni-Bird et al.
patent: 5987885 (1999-11-01), Kizer et al.
patent: 6003303 (1999-12-01), Peter-Hoblyn et al.
patent: 21 29 210 (1972-12-01), None
patent: 4039688A1 (1991-06-01), None
patent: 19746658A1 (1999-04-01), None
patent: 0879633A2 (1998-11-01), None
patent: 09125972 (1995-11-01), None
patent: 09184421 (1995-12-01), None
patent: 96 29141 (1996-09-01), None
German Patent Office Search Report.
Denion Thomas
Morgan & Finnegan , LLP
Trieu Thai-Ba
Valeo Thermique Moteur
LandOfFree
Controlled temperature catalytic converter, in particular... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Controlled temperature catalytic converter, in particular..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Controlled temperature catalytic converter, in particular... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2445330