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Publication numberUS3837165 A
Publication typeGrant
Publication dateSep 24, 1974
Filing dateSep 7, 1972
Priority dateSep 10, 1971
Also published asCA957750A1, DE2244227A1, DE2244227B2, DE2244227C3
Publication numberUS 3837165 A, US 3837165A, US-A-3837165, US3837165 A, US3837165A
InventorsArrigoni V, Gaetani B, Marchesi G, Zanoni G
Original AssigneeSnam Progetti
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Automatic device for controlling catalytic mufflers
US 3837165 A
Abstract
A device for automatically controlling a by-pass electro-valve of a catalytic muffler comprising three inlet stages, the first inlet stage is responsive to the speed or number of engine revolutions, the second inlet stage is responsive to the throttle position and includes a retarding circuit and store, and the third inlet stage is responsive to the temperature of the catalyst and includes means for comparing the temperature of the catalyst with a maximum allowable temperature (TMAX.) and a predetermined running temperature (TS). The three inlet stages are electrically coupled to an outlet stage which includes a timer for producing a pulse of predetermined duration.
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Description  (OCR text may contain errors)

United States Patent r191 Arrigoni et al.

[ AUTOMATIC DEVICE FOR CONTROLLING CATALYTIC MUFFLERS [75] Inventors: Virgilio Arrigoni, San Donato Milanese; Bruno Gaetani, Milano; Gianfranco Marchesi; Gianfranco Zanoni, both of San Donato Milanese, all of Italy [73] Assignee: Snam Progetti S.p.A., Milan, Italy [22] Filed: Sept. 7, 1972 [21] Appl. No.: 287,009

[30] Foreign Application Priority Data Sept. 10, 1971 Italy 28446/71 [52] U.S. Cl 60/277, 60/288, 60/294 [51] Int. Cl. F02b 75/10 [58] Field of Search 60/288, 287, 285, 294,

[56] References Cited UNITED STATES PATENTS 3,440,817 4/1969 Saufferer 60/288 [451 Sept. 24, 1974 Primary Examiner-Douglas Hart Attorney, Agent, or FirmRalph M. Watson 57 ABSTRACT A device for automatically controlling a by-pass electro-valve of a catalytic muffler comprising three inlet stages, the first inlet stage is responsive to the speed or number of engine revolutions, the second inlet stage is responsive to the throttle position and includes a retarding circuit and store, and the third inlet stage is responsive to the temperature of the catalyst and includes means for comparing the temperature of the catalyst with a maximum allowable temperature (T and a predetermined running temperature (T The three inlet stages are electrically coupled to an outlet stage which includes a timer for producing a pulse of predetermined duration.

6 Claims, 2 Drawing Figures AUTOMATIC DEVICE FOR CONTROLLING CATALYTIC MUFFLERS The present invention relates to a device for the automatic control of catalytic mufflers like the ones used at present time in order to reduce the outlet of pollutants in exhausts of motor vehicles having a controlled ignition. For increasing the life of the muffler catalyst it is suitable to cut out therein the flow of the gases in those cases in which said flow would result particularly damaging or useless, i.e., when the motor presents already a low outlet of pollutants, this being the case, e.g., at high speeds outside inhabited places, and when a too high temperature occurs in the catalyst due to running defects.

The cutting out of the gas flow through the catalytic muffler is generally obtained by-passing the muffler through a by-pass valve operated by a control device.

Object of the present invention is to provide a control device allowing the automatic opening of the by-pass valve once reached determined conditions of temperature, speed or number of revolutions and throttle opening. Said device according to the invention comprises three stages responsive to the vehicle speed or number of revolutions of the engine, to the opening degree of the throttle and to the catalyst temperature respectively, and an outlet stage which, controlled by said inlet stages, operates a by-pass valve.

According to an essential feature of theinvention the stage responsive to the opening degree of the throttle delivers a by-pass valve opening signal to the outlet stage only if the throttle opening keeps higher than a certain value for a determined time, this being the case, e.g., for highway runnings; the catalytic muffler is therefore switched on, as necessary, for full and shorttimed accellerations (city traffic).

According to a further essential feature of the invention the stage responsive to the catalyst temperature is responsive both to the temperature gradient as to the time (derivative action), so as to intervene before a destructive temperature T is reached, and to the integral as to the time of the temperature-rise over the prefixed temperature T,, so as to prevent the permanence of temperatures which, even if not destructive, will age rapidly the catalyst. Summing up the device according to the present invention keeps automatically opened the by-pass valve, cutting out thereby the gas flow through the catalytic muffler, in the following cases:

when the vehicle speed or the number of revolutions of the engine exceeds a prefixed value, e.g., 50 km/h in third gear;

when the throttle opening exceeds a determined value, e.g., about 80, for a determined period of time, so that the catalytic muffler is switched on when the full accelerations are short-timed;

when the catalyst temperature exceeds a limit value T beyond which the catalyst would be damaged, or assumes a gradient as to the time higher than a prefixed value so as to prevent the reaching of destructive high temperatures;

when the temperature exceeds for a certain time (integral action) a prefixed value T, whose permanence shortens the catalyst life.

According to a further essential feature of the invention the outlet stage of the control device is realized so as to prevent the continuous opening and closing of the by-pass valve when the logical valve opening signals, coming from the inlet stages, fluctuate around limit values of intervention. This is practically obtained by exciting with an outlet signal of a gate circuit OR, at the inlet of which there is convergence of the logical signals coming from the other inlet stages, a retarding logic consisting of a timer delivering a pulse of controlled duration, and sending the outlet signal of said gate circuit OR and the outlet signal of said timer to the inlet of another gate circuit OR whose outlet controls directly the by-pass valve. In this way, even if for any reason, e.g., fluctuation around the limit values of intervention, there is no by-pass valve opening signal at the inlet of the first gate circuit OR," the timer, once excited, keeps on delivering the signal for keeping opened said by-pass valve for the whole prefixed period of time.

Finally it has to be pointed out that the whole automatic control device according to the invention may be fed by the vehicle battery or by the network for roller tests.

The invention will be now illustrated with reference to the enclosed drawing showing a preferred form ofpractical realization given only by way of example, since many technical and network variants may be thought without departing from the scope of the present invention.

FIG. 1 shows schematically in a block diagramm the by-pass of a catalytic muffler through an electro-valve automatically controlled by a control electromechanical device according to the invention;

FIG. 2 shows in a block diagramm the circuit schema of the control electro-mechanical device of FIG. 1 according to the invention.

With reference to figures, 1 indicates the catalytic muffler to be protected, 2 indicates the by-pass electro-' valve and 3 the automatic control device. Said automatic control device 3 comprises according to the in vention three inlet stages responsive to the vehicle speed or the number of engine revolutions, to the throttle opening degree and to the catalyst temperature of the catalytic muffler 1 respectively, and an outlet stage reached by the logical signals coming from said inlet stages and which controls the by-pass valve 2.

The inlet stage responsive to the vehicle speed or the number of engine revolutions comprises (see FIG. 2) a speedometer dynamo 4 or a device indicating the number of the engine revolutions, which delivers a voltage proportional to the engine speed or number of revolutions, this voltage being compared in node 5 with a reference voltage set up by a potentiometer 6. The difference between the two said voltages operates then a speed level discriminator 7 whose outlet is connected with the OR" gate circuit 8 of the outlet stage. In this way at the outlet of discriminator 7 a valve opening sig nal will appear only'if the voltage delivered by the speedometer dyamo or by the device indicating the number of revolutions is higher than the voltage set up on potentiometer 6, i.e., therefore, when the speed or the number of the revolutions of the engine exceeds the prefixed value corresponding, e.g., to 50 Km/h in third gear.

The inlet stage responsive to the throttle opening degree comprises a level discriminator 9 at the inlet of which one applies the difference between the voltage, signal proportional to the position of throttle 10, obtained, e.g., by means of a potentiometer whose slider is rigidly connected with the throttle, and the reference voltage set up through potentiometer 11.

Here too, therefore, it is possible to have a signal at the outlet of discriminator 9 only if said difference is positive, i.e., if the throttle opening degree is higher than the set up reference value, corresponding, e.g., to

- 24 releases by-pass valve 2 before T temperature is reached and prevents therefore the reaching of high dea throttle rotation of 80. This discriminator outlet signal is not however directly sent to OR gate circuit 8 of the outlet stage, but is applied at the same time to a retarding circuit 12, delivering a pulse after a prefixed period of time, and to an AND type circuit 13 reached too by the retarding pulse. The AND circuit outlet excites then a store 14 whose outlet is directly connected with said OR gate circuit of the outlet stage. In this way, store 14 will deliver to the outlet stage a valve opening signal not when there is a signal at the outlet of discriminator 9, i.e., when the throttle opening exceeds a certain prefixed level, but only when the throttle opening keeps higher than said level for a period of time at least corresponding to the delay time of retarding circuit 12. In fact AND gate circuit 13 opens and excites store 14 only when there are at its inlet both signals and therefore, even if there is the outlet signal of discriminator 9 but its duration is lower than the one required by retarding circuit 12 to give its pulse, AND circuit 13 does not open. It is possible in this way to prevent that by-pass valve 2 opens in case of full accellerations having a short duration, e.g., ac-

cellerations occurring at the changing of gears (city traffic).

The presence of store 14 is then necessary since the outlet signal ofAN D circuit 13 is a short-timed pulse whereas the valve opening signal must be a signal keeping on till the throttle opening has gone under the prefixed level. Store 14, comprising a series of flip-flop or NOR circuits, has indeed the dutyv of storing and transforming the exciting pulse at its inlet into a continuous signal at its outlet and of keeping this signal till at the outlet of discriminator 9 there is a signal. When there is no more this latter signal, since the throttle opening has gone under the prefixed level, store 14 is set to zero by the same outlet signal of discriminator 9 inverted by inverter 15.

In FIG. 2 it has been shown too indicator 16 by means of which it is possible to visualize the value of the speed or of the number of engine revolutions and the throttle opening degree.

The third inlet stage responsive to the catalyst temperature of catalytic muffler l is, on the contrary, constituted by a thermoelement 17 whose voltage signal, proportional to said temperature, is amplified by means of operational amplifier l8 and visualized by indicating device 19. The outlet signal of amplifier 18 is then differentiated by means of differentiating RC circuit, comprising resistance 20 and capacitor21, and then compared in node 22 with the reference signal to be prefixed on pretentiometer 23 and corresonding to the limit destructive temperature T e.g., 800C. The resulting difference signal is then sent to a level discriminator 24 whose outlet is connected with said OR gate I circuit of the outlet stage. In this way in node 22 there is only a signal which is the sum of the signal proportional to the temperature and of its. derivative as to the time and therefore the discriminator 24 delivers a valve opening signal at its outlet not when the catalyst temperature reaches T value, but when this value is reached by said sum signal. Summing up discriminator structive temperatures. On the other side the signal of thermoelement l7, amplified by operational amplifier 18, is compared too in node 25 with a reference signal, delivered by potentiometer 26. proportional to a certain running temperature "1",, e.g., 500C, a catalyst temperature-rise as to the latter being not destructive but at the long run shortening the catalyst life.

The temperature-rise signal resulting in node 25 is then sent, at the same time, to a terminal of a relay 27 and to the inlet of a mean level discriminator 28 whose outlet, exciting the above mentioned relay, switches on the same signal on the outlet of an integrator 29 which, integrating this temperature-rise signal, will take a time proportional to the magnitude of this signal for reaching the integral threshold level T predetermined by potentiometer 30. The reaching of the integral threshold limit T this meaning that the temperature-rise as to the running temperature lasts for a certain period of time and is therefore harmful for the catalyst of the catalytic muffler, is detected by level discriminator 31 which excites store 32 whose outlet is connected with said OR gate circuit 8 of the outlet stage.

Said store 32 is like and has the same function of store 14 already cited and, like the latter, is set to zero by the outlet signal of discriminator 28 inverted by inverter 33.

By means of this latter part of the device circuit it is possible therefore to send to the outlet stage a valve opening signal every time that the catalyst temperature exceeds a certain critical value T, whose lasting, harmful for the catalyst, allows the outlet of integrator 29 to reach the integral threshold value T P16. 2 visualizes too potentiometer 37 for calibrating operational amplifier 18.

Finally the outlet stage of the device according to the invention comprises the already cited OR gate circuit 8 reached by the logical valve opening signals coming from the inlet stages, whose outlet excites a timer 34 capable of delivering a pulse of duration to be prefixed. Said duration-prefixed pulse, produced by timer 34 once excited, is sent together with the outlet signal of OR gate circuit 8 to the inlet of another OR" gate circuit 35 whose outlet 36 operates directly bypass electro-valve 2.

In this way by-pass valve 2 keeps opened not only when there is a single logical signal at the inlet of OR gate circuit 8, but keeps opened even if said logical signal disappears because, e.g., of its fluctuation around its limit value of intervention. ln fact, timer 34, once excited, keeps on delivering a valve opening signal for the whole period of time therein prefixed.

What we claim is:

1. An automatic control device for controlling a bypass electro-valve in an arrangement comprising an engine having a throttle and an exhaust system, said exhaust system having a catalytic muffler containing a catalyst and a by-pass duct, around said muffler, containing said by-pass electro-valve, comprising:

three inlet stages;

said first inlet stage being responsive to the speed or number of revolutions of the engine;

said second inlet stage being responsive to the position of the throttle, including a level discriminator for receiving at its input a difference voltage including a voltage proportional to the position of the throttle and a reference voltage, retarding circuit electrically coupled to said level discriminator for producing an output pulse after a predetermined time in response to an output signal from said level discriminator, coincident gate means electrically coupled to the output of said level discriminator and said retarding circuit to produce an output signal in response to signals from said level discriminator and said retarding circuit, a store electrically coupled to the output of said coincident gate means;

said third inlet stage being response to the temperature of the catalyst; and

an outlet stage for actuating the by-pass electro-valve in response to signals from said inlet stages.

2. An automatic control device as claimed in claim 1 wherein:

said store includes a plurality of flip-flops or NOR gates;

an inverter also electrically couples the output of said level discriminator directly to said store to set the output signal from said store to zero in the absence of an output signal from said coincident gate means.

3. An automatic control device for controlling a bypass electro-valve in an arrangement comprising an engine having a throttle and an exhaust system, said exhaust system having a catalytic muffler containing a catalyst and a by-pass duct, around said muffler, containing said by-pass electro-valve, comprising:

three inlet stages;

said first inlet stage being responsive to the speed or number of revolutions of the engine;

said second inlet stage being responsive to the position of the throttle;

said third inlet stage being responsive to the temperature of the catalyst, including thermoelement means for providing an output signal proportional to the temperature of the catalyst, an operational amplifier electrically coupled to said thermoelement, differentiating circuit means electrically coupled to the output of said operational amplifier, potentiometer means for providing a reference signal corresponding to a maximum temperature limit (T a level discriminator electrically coupled to said potentiometer means and said differentiating circuit means for receiving at its input a difference signal; and

an outlet stage for actuating the by-pass electro-valve in response to signals from said inlet stages.

4. An automatic control device as claimed in claim 3 including:

second potentiometer means electrically coupled to the output of said operational amplifier to provide a reference signal corresponding to a predetermined running temperature (T a relay having one of its terminals electrically coua second level discriminator also electrically coupled to the output of said operational amplifier to actuate said relay;

an integrator electrically coupled to another terminal of said relay, said integrator providing an output signal in response to actuation of said relay by said second level discriminator;

third potentiometer means electrically coupled to the output of said integrator to provide a reference signal corresponding to an integral threshold temperature limit (T,);

a third level discriminator electrically coupled to the output of said integrator and said third potentiometer means; and

a store electrically coupled to the output of said third level discriminator.

5. An automatic control device as claimed in claim 4 wherein:

said store includes a plurality of flip-flops or NOR" gates;

an inverter also electrically couples the output of said second level discriminator to said store to set the output signal from said store to zero in the absence of an output signal from said third level discriminator.

6. An automatic control device for controlling a bypass electro-valve in an arrangement comprising an engine having a throttle and an exhaust system, said exhaust system having a catalytic muffler containing a catalyst and a by-pass duct, around said muffler, containing said by-pass electro-valve, comprising:

three inlet stages;

said first inlet stage being responsive to the speed or number of revolutions of the engine;

said second inlet stage being responsive to the position of the throttle;

said third inlet stage being responsive to the temperature of the catalyst; and

an outlet stage including a first OR gate to receive the output signals from said inlet stages, a second OR gate having a first input terminal electrically coupled to the output of said first OR gate, a timer electrically coupled to the output of said first OR" gate and to a second input terminal of said second OR gate, said timer producing an output pulse of predetermined duration in response to an output signal from said first OR gate, the output from said second OR gate directly controlling the by-pass electro-valve.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3440817 *Sep 3, 1964Apr 29, 1969Daimler Benz AgCatalytic converter system for exhaust gases of internal combustion engines
US3548792 *Feb 11, 1969Dec 22, 1970Judson G PalmerControl apparatus for internal-combustion engines
US3670496 *Jul 27, 1970Jun 20, 1972Nissan MotorExhaust gas after-burning system
US3680318 *Dec 22, 1970Aug 1, 1972Kunihiko SugiharaCentralized air-pollution preventive system
US3705497 *May 10, 1971Dec 12, 1972Hollins J RVehicle engine emissions control system
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3948228 *Nov 6, 1974Apr 6, 1976The Bendix CorporationExhaust gas sensor operational detection system
US3961478 *Dec 6, 1974Jun 8, 1976Dr. -Ing. H.C.F. Porsche AktiengesellschaftInstallation for the catalytic afterburning of exhaust gases in the exhaust gas system of an internal combustion engine
US5560200 *Jun 7, 1995Oct 1, 1996Emitec Gesellschaft Fuer Emissionstechnologie MbhMethod and apparatus for functional monitoring of a catalytic converter
US5591905 *Aug 31, 1995Jan 7, 1997Mitsubishi Denki Kabushiki KaishaDeterioration detecting apparatus for catalytic converter
US6712888Jun 24, 2002Mar 30, 2004Albert F. SiskaEngine emission control system and method
US7062908 *Oct 20, 2003Jun 20, 2006Suzuki Motor CorporationConstruction for exhaust emission control
Classifications
U.S. Classification60/277, 60/288, 60/294
International ClassificationF02D41/14, F01N3/20, F16K31/06, F01N3/08
Cooperative ClassificationF01N2410/02, F02D41/1446, F01N2410/10, F01N3/2053, F01N2390/02
European ClassificationF01N3/20C, F02D41/14D3B