Exhaust-gas recirculating system for internal-combustion engines
AssigneeRobert Bosch GmbH
InventorKlaus Krieger
Life of this patent
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Abstract
An exhaust-gas recirculating system for internal-combustion engines includes a fuel-injection system which generates a hydraulic back pressure during control of the load- and speed-dependent variation of the beginning of delivery within a given set of load and speed characteristics. An hydraulic back pressure is used directly to control a pneumatic directional valve by means of an hydraulic servomotor. This directional valve, in turn, controls a vacuum-operated exhaust-gas recirculation valve. The hydraulic back pressure is also controlled by means of a pressure-holding valve and a constricting throttle.
Claims7
An exhaust gas recirculating system for an internal combustion engine having an air intake line and an exhaust gas line, said system comprising an exhaust gas recirculating line which connects said exhaust line to said intake line;
- an exhaust gas recirculating valve for controlling the passage of gas in said recirculating line in response to a control medium;
- a directional valve, provided with and acuated by a hydraulically actuated servomotor, for supplying said control medium to said recirculating valve;
- a fuel injection system for supplying fuel to the internal combustion engine, said fuel injection system providing a hydraulic control pressure for a range of engine characteristics including a minimum load and a minimum speed;
- and means for controlling said servomotor, and thereby said directional valve, in response to said hydraulic control pressure, said means for controlling the servomotor including means for directly applying the hydraulic control pressure to said servomotor.
An exhaust gas recirculating system for an internal combustion engine having an intake line and an exhaust gas line, said recirculating system comprising an exhaust gas recirculating line which connects the exhaust line to the intake line;
- an exhaust gas recirculation valve, arranged in said recirculating line, for controlling the passage of exhaust gases to said intake line;
- a fuel injection pump having means for producing a hydraulic pressure that increases with engine speed, means responsive to said hydraulic pressure to vary the timing of the beginning of fuel delivery, and control valve means, responsive to engine load and speed, for discharging a portion of the hydraulic pressure medium in dependence upon a minimum speed and a minimum load;
- a constricting throttle, connected to said control valve means, for constricting the flow of said hydraulic pressure medium;
- control means for converting the back pressure between said valve means and said constricting throttle into a mechanical variable for said exhaust gas recirculation valve;
- and a pressure holding valve, arranged in parallel with said constricting throttle, through which excess hydraulic pressure medium is discharged while a back pressure is maintained.
Dependencies are inferred from the claim text.