US3890946A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and system to reduce noxious components in the exhaust emission from internal combustion engines with carburetor supply
Assignee: Robert Bosch GmbH
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Filing: 1974-06-12
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Granted: 1975-06-24
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Expires: 1994-06-12
Abstract
Abstract The carburetor for the engine is set to provide a slightly lean mixture, for example at an air number of lambda 1.1. A fuel injection valve is located in the induction tube, or inlet manifold to the engine. The opening time of the valve is controlled in dependence on inlet manifold pressure, or other operating parameters (and may be non-linear to match nonlinearities of the carburetor) and, additionally, by sensed composition of the exhaust gases from the engine to provide additional fuel so that the overall fuel-air mixture, supplied by the carburetor as well as the injected fuel will be just under the stoichiometric level, for example at an air number of approximately 0.98, so that the exhaust gases will be reducing and permit reduction of NOx compounds in a catalytic converter with presence of minimum amounts of CO and CH compounds in the exhaust.
Inventors
- 👤 Josef Wahl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:18
CPC Classifications
F; F02; F02D; F02D35/00; F02D35/0015; F02D35/0046; F02D35/0092
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
156 words
Method to reduce noxious components in the exhaust from internal combustion engines having a carburetor to supply a fuelair mixture to the engine, comprising the steps of supplying fuel from the carburetor to the engine in a quantity less than that forming a stoichiometric level to supply a lean fuel-air mixture to the engine; sensing the composition of the exhaust gases by testing oxygen content therein, and providing a sensing signal representative of oxygen in the exhaust gases; intermittently injecting fuel to the fuel-air mixture being supplied to the engine; and controlling the injection time, for each injection of fuel, in dependence on sensed composition of the exhaust gases by injecting fuel during respectively longer, or shorter time intervals, as the sensed composition of the exhaust gases changes between lean ( lambda >1) and rich ( lambda <1) mixture to provide an overall fuel-air mixture being applied to the engine which is just below stoichiometric value.
Claim 2
Dependent Claim
156 words
Method to reduce noxious components in the exhaust from internal combustion engines having a carburetor to supply a fuelair mixture to the engine, comprising the steps of supplying fuel from the carburetor to the engine in a quantity less than that forming a stoichiometric level to supply a lean fuel-air mixture to the engine; sensing the composition of the exhaust gases by testing oxygen content therein, and providing a sensing signal representative of oxygen in the exhaust gases; intermittently injecting fuel to the fuel-air mixture being supplied to the engine; and controlling the injection time, for each injection of fuel, in dependence on sensed composition of the exhaust gases by injecting fuel during respectively longer, or shorter time intervals, as the sensed composition of the exhaust gases changes between lean ( lambda >1) and rich ( lambda <1) mixture to provide an overall fuel-air mixture being applied to the engine which is just below stoichiometric value.
Claim 3
Dependent Claim
68 words
Method according to claim 1, wherein the air number of the fuel-air mixture being supplied to the engine by the carburetor has an air number of about 1.1, and the step of intermittently injecting fuel comprises adding fuel in such a a quantity that the overall air number of the fuel-air mixture supplied to the engine by both the carburetor and the fuel injection valve is about 0.98.
Claim 4
Dependent Claim
36 words
Method according to claim 1, wherein the step of controlling the injection time comprises the step of sensing inducTion tube pressure and said injection time is further controlled as a function of the induction tube pressure.
Claim 5
Dependent Claim
89 words
Method according to claim 1, wherein the step of controlling the injection time comprises the step of determining the relationship of operating characteristics of the engine carburetor with respect to the engine operating conditions and deriving an error function representative of non-linearities in said relationship; and modifying the injection time in accordance with a function which compensates for said error function to provide an overall fuel-air mixture being applied to the engine in which the relative composition of fuel and air is essentially unvarying regardless of engine operating conditions.
Claim 6
Dependent Claim
57 words
Method according to claim 1, wherein the step of injecting fuel into the fuel-air mixture comprises supplying fuel at a substantially constant pressure to an injection valve to vary the quantity of fuel added by said injection step to the fuel-air mixture derived from the carburetor substantially only as a function of injection time of said valve.
Claim 7
Dependent Claim
151 words
System to reduce the noxious components in the exhaust from an internal combustion engine (15) having a carburetor (27) to supply a fuel-air mixture to the engine, in which the carburetor supplies a lean fuel-air mixture having an air number greater than unity ( lambda >1.0) carrying out the method of claim 1, comprising sensing means (37) responsive to the exhaust gases from the engine and providing a sensing signal representative of oxygen in the exhaust from the engine; a fuel injection valve (30) in the induction system (20) to the engine; control means (31) connected to energize said injection valve for intermittent opening, said sensing means (37) being connected to said control means (31) to control the time of energization of said injection valve, and hence the duration that said valve is open and hence the quantity of fuel injected, as a function of sensed composition of the exhaust gases.
Claim 8
Dependent Claim
45 words
System according to claim 6, wherein the control means (31) comprises a monostable flip-flop (FF) (31) connected to and controlled by said sensing signal to change the duration of the unstable state of said monostable FF in dependence on sensed composition of the exhaust gases.
Claim 9
Dependent Claim
82 words
System according to claim 7, wherein the control means further comprises an integrating circuit (35) and a threshold switch (36), the sensing signal being applied to said threshold switch which changes state when the sensing signal exceeds a predetermined reference limit, the output of the threshold switch being applied to the integrator (35) to provide an integrated signal, varying in positive or negative going direction, and depending on the time that said sensing signal passes the threshold level of said threshold switch.
Claim 10
Dependent Claim
56 words
System according to claim 6, further comprising means (46) sensing pneumatic conditions in the induction tube (20) to the internal combustion engine and further controlling the control means (31) to vary time of energization of said injection valve, and hence the duration that said valve is open, in dependence on pneumatic conditions in said induction tube.
Claim 11
Dependent Claim
25 words
System according to claim 9, wherein the means sensing pneumatic conditions in the induction tube comprises a pressure transducer sensing vacuum in the induction tube.
Claim 12
Dependent Claim
28 words
System according to claim 9, wherein the pneumatic sensing means comprises an air mass flow transducer responsive to air mass flow in the induction tube of the engine.
Claim 13
Dependent Claim
62 words
System according to claim 7, further comprising transducer means responsive to at least one of the pneumatic conditions in the induction tube of the engine: vacuum; mass air flow; said transducer means being connected to said monostable FF and additionally controlling the unstable state of said monostable FF (31) in dependence on pressure, or air flow conditions, respectively, in said induction tube.
Claim 14
Dependent Claim
43 words
System according to claim 7, wherein said moNostable FF stage comprises at least one correction terminal input (33'', 60) to permit modification of the unstable time of the monostable FF (31) as a function of a correction, or operating parameter of the engine.
Claim 15
Dependent Claim
25 words
System according to claim 7, wherein the unstable state of the monostable FF is controlled in dependence on position of the throttle of the engine.
Claim 16
Dependent Claim
69 words
System according to claim 7, wherein the monostable FF includes a variable circuit element (42, 43, 44) affecting the unstable time, and hence the time of energization of said fuel injection valve, and said sensing means (37) is connected to said FF to provide for multiplicative modification of change in the unstable time of said monostable FF, with respect to the variation of value of said variable circuit element.
Claim 17
Dependent Claim
46 words
System according to claim 7, wherein the output of the monostable FF is connected to the injection valve (30) to energize the fuel injection valve when the monostable FF is in unstable state, said fuel injection valve having fuel applied thereto at a substantially constant pressure.
Claim 18
Dependent Claim
41 words
System according to claim 7, further comprising a trigger means (34) connected to and controlled by the rotation of the engine and triggering the monostable FF to change from stable to unstable state in predetermined relationship to rotation of the engine.
Claim 19
Dependent Claim
34 words
System according to claim 7, wherein the monostable flip-flop (31) is triggered from stable into unstable state by a pulse source, the pulse repetition rate of which is dependent on loading of the engine.
Claim 20
Dependent Claim
49 words
System according to claim 7, wherein the monostable FF includes an inductive circuit (42), the inductivity of said circuit being variable, and forming one control parameter determining the unstable time of said monostable FF, the inductivity varying as a function of an operating, or operation parameter of said engine.
Claim 21
Dependent Claim
111 words
System according to claim 7, wherein the FF includes a non-linear element (43; FIG. 4) and having variable characteristics which change upon change in operating, or operation parameters of the engine; the carburetor (27) has a non-linear operating characteristic with respect to change in an operation, or operating parameter of the engine; and the non-linearity of said element in said monostable FF being selected to compensate for, and counteract non-linearities in the characteristics of the carburetor upon change of a respective operation, or operating parameter of the engine, said element responding to operation, or operating parameters of the engine which are affected by the non-linearities of the characteristics of the carburetor.
Claim 22
Dependent Claim
160 words
In combination with an internal combustion engine, operating by carrying out the method of claim 1, a fuel supply system comprising a carburetor set to provide an air-fuel mixture at an air number greater than unity, in quantities supplying the major portion of the air-fuel mixture requirements of the engine; a fuel injection valve in the induction system to the engine; sensing means (37) responsive to the exhaust gases from the engine and providing a sensing signal representative of oxygen in the exhaust from the system; and control means connected to energize said injection valve for intermittent opening, said sensing means being connected to said control means to control the time of energization of said injection valve, and hence the duration that said valve is open as a function of sensed composition of exhaust gases, the quantity of fuel injected being a minor proportion of the fuel necessary to provide a fuel-air mixture having an air number just under unity.
Claim 23
Dependent Claim
51 words
Fuel supply system according to claim 21, wherein the fuel supplied by the carburetor provides about 70-90% of the fuel requirement of the fuel-air mixture required for operation of the engine; and the fuel injected by the fuel injection valve comprises the remaining 70-30% of total fuel requirements of the engine.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-23 | 1978-12-23 | 1979-06-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-23 | 1982-12-23 | 1983-06-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-23 | 1986-12-23 | 1987-06-24 | $7700.00 | Window Closed / Lapsed |