Internal-combustion engines – Engine speed regulator – By changing valve lift
Patent
1983-01-10
1984-10-30
Moy, Magdalen Y. C.
Internal-combustion engines
Engine speed regulator
By changing valve lift
123501, 123502, 123569, F02P 504
Patent
active
044794738
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a system for controlling emissions from a diesel engine by both recirculating engine exhaust gases and simultaneously modulating the fuel injection timing.
The simultaneous control of unburned hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in a diesel engine requires a precise control of exhaust gas recirculation (EGR) and injection timing. NOx control can be obtained by the use of EGR to reduce the oxygen concentration in the combustion chamber. However, the amount than can be used is limited both by the breathing capacity of the engine and the percentage of air in the charge that is available for combustion. An adequate amount of excess air must be maintained for a smoke-free combustion. If the EGR rate has been limited by the breathing capacity of the engine, further NOx reduction can still be obtained by the use of retarded injection timing. At light loads, where the amount of EGR used does not limit the breathing capacity of the engine, the injection timing can be advanced for improved HC control.
This invention, therefore, relates to a diesel engine control system that will automatically schedule EGR and injection timing in a manner to provide an optimum control of HC, CO and NOx emissions.
It is another object of this invention to provide a diesel engine vacuum-mechanical emission control system that includes a three-dimensional cam responsive to engine speed and load conditions and fuel injection pump delivery changes to provide a varying schedule of EGR flow, coupled with advancing or retarding the fuel pump injection timing to minimize the output of emissions. Advancing of the injection timing provides a longer resident time permitting a better consumption of the fuel in the combustion chamber. Retarding the injection timing reduces the peak temperature of combustion and thereby reduces the production of NOx.
The control of emissions from a diesel engine by controlling both EGR and fuel injection timing is known. For example, SAE Report No. 800335, April 1980, suggests on page 260 that exhaust gas recirculation and fuel injection timing modulation can significantly affect the emission levels of a swirl chamber Diesel. However, no means are disclosed for accomplishing the desired results.
The use of a three-dimensional cam per se to control fuel flow also is known. For example, the February 15, 1971 edition of Mechanical Design and Power Transmission, on page 62, discloses such a use. In this case, however, the use of a mechanical system was suggested, but no details of a combined system such as are provided by this invention were disclosed.
Other quasi-mechanical systems used to control emissions from an engine also are known. For example, Nakajima et al, U.S. Pat. No. 3,636,934, discloses the use of switches closed or controlled as a function of the position of the carburetor throttle valve and engine or vehicle speeds to control emissions.
Rieger, U.S. Pat. No. 3,791,360, shows an electromagnetically operated EGR valve.
Bier, U.S. Pat. No. 3,842,814, shows the use of a carburetor throttle control valve to control EGR flow.
Young et al, U.S. Pat. No. 3,915,134, discloses an electronic system including a feedback circuit to control EGR flow and minimize smoke in the engine exhaust.
Naito et al, U.S. Pat. No. 3,916,857, discloses a further control for EGR flow as a function of load changes and accelerator lever position.
Kern et al, U.S. Pat. No. 4,020,809, shows merely a diesel engine EGR control system.
Nohira et al, U.S. Pat. No. 4,040,402, discloses an EGR system responsive to various operating conditions of the engine to control the flow.
Wirsching et al U.S. Pat. No. 3,015,326, discloses an arrangement for controlling the injection timing of a fuel injection pump including the use of a three-dimensional cam. However, no control of EGR flow in conjunction with the fuel injection timing is provided.
Garcea, U.S. Pat. No. 3,146,770, also shows the control of fuel injection timing by the use of a three-dimensional cam, without, however, the simult
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Ford Motor Company
McCollum Robert E.
Moy Magdalen Y. C.
Sadler Clifford L.
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