Dual mode EGR valve

An EGR system for use on an internal combustion engine, the EGR system comprising:

• at least one hydraulic master cylinder;
• a slave cylinder in fluid communication with the hydraulic master cylinder and having a slave piston;
• a hydraulic manifold in fluid communication with the at least one hydraulic master cylinder and the slave cylinder;
• an EGR valve coupled to the slave piston and biased in a closed position.
• a three-port control valve having a first port in fluid communication with the hydraulic manifold, a second port in fluid communication with a source of hydraulic fluid when the three-port control valve is in a first state, and a third port in fluid communication with a hydraulic fluid drain when the three-port control valve is in a second state, the second port having a check valve to prevent backflow of hydraulic fluid from the hydraulic manifold into the source of hydraulic fluid;
• a mode control valve separating the hydraulic manifold and the slave cylinder, the mode control valve comprising:
• a check valve that permits fluid to flow from the hydraulic manifold into the slave cylinder;
• a closeable bypass that, when open, permits fluid to flow from the hydraulic manifold into the slave cylinder and from the slave cylinder into the hydraulic manifold;
• and
• wherein the at least one hydraulic master cylinder is actuated by at least one rocker arm of the engine.

An EGR system, comprising:

• a EGR valve biased in a closed position;
• a piston coupled to the EGR valve;
• a spool valve coupled to the piston to permit the EGR valve to be opened and closed;
• an actuator coupled to the spool valve.

A dual mode EGR system for use on a combustion engine having an intake line and a compressor, the EGR system comprising:

• an EGR passage having at least one aperture that opens into the intake line downstream of the compressor;
• an EGR valve that blocks flow through the EGR passage when closed;
• an actuator coupled to the EGR valve, and adapted to operate in at least a first mode and a second mode;
• wherein in the first mode, the actuator at least partially opens the EGR valve and leaves it at least partially open for a period at least long enough for two cylinders to fire;
• and
• wherein in the second mode, the actuator successively opens and closes the EGR valve synchronously with increases in a pressure in the EGR passage.

A dual mode EGR system for use on a combustion engine having an intake line and a compressor, the EGR system comprising:

• an EGR passage having at least one aperture that opens into the intake line downstream of the compressor;
• an EGR valve that blocks flow through the EGR passage when closed,
• a spring disposed to bias the EGR valve in a closed position;
• an actuator coupled to the EGR valve, and adapted to operate in at least a first mode and a second mode, the actuator comprising:
• at least one hydraulic master cylinder;
• a slave cylinder in fluid communication with the hydraulic master cylinder and having a slave piston, the slave piston being coupled to the EGR valve;
• and
• a hydraulic manifold in fluid communication with the at least one hydraulic master cylinder and the slave cylinder;
• a three-port control valve having a first port in fluid communication with the hydraulic manifold, a second port in fluid communication with a source of hydraulic fluid when the three-port control valve is in a first state, and a third port in fluid communication with a hydraulic fluid drain when the three-port control valve is in a second state, the second port having a check valve to prevent backflow of hydraulic fluid from the hydraulic manifold into the source of hydraulic fluid;
• and
• a mode control valve separating the hydraulic manifold and the slave cylinder, the mode control valve comprising:
• a check valve that permits fluid to flow from the hydraulic manifold into the slave cylinder;
• and
• a closeable bypass that, when open, permits fluid to flow from the hydraulic manifold into the slave cylinder and from the slave cylinder into the hydraulic manifold;
• and
• wherein when the engine operates near torque peak the actuator functions in the second mode by placing the three-port control valve in the second state and opening the closable bypass.

A dual mode EGR system for use on a combustion engine having an intake line and a compressor, the EGR system comprising:

• an EGR passage having at least one aperture that opens into the intake line downstream of the compressor;
• an EGR valve that blocks flow through the EGR passage when closed,
• a spring disposed to bias the EGR valve in a closed position;
• an actuator coupled to the EGR valve, and adapted to operate in at least a first mode and a second mode, the actuator comprising:
• a piston coupled to the EGR valve;
• a cam in mechanical communication with the piston, such that when the cam rotates the piston is actuated;
• a motor coupled to the cam;
• and
• wherein the motor of the actuator is moved to and left in an angular position that opens the EGR valve unless the engine is operating near torque peak.

A dual mode EGR system for use on a combustion engine having an intake line and a compressor, the EGR system comprising:

• an EGR passage having at least one aperture that opens into the intake line downstream of the compressor;
• an EGR valve that blocks flow through the EGR passage when closed,
• a spring disposed to bias the EGR valve in a closed position;
• an actuator coupled to the EGR valve, and adapted to operate in at least a first mode and a second mode, the actuator comprising:
• a piston coupled to the EGR valve;
• a cam;
• a chamber;
• a fill line adapted to direct hydraulic fluid into the chamber;
• a variable tappet in contact with the chamber and that places the cam and piston in mechanical communication, such that the piston opens the EGR valve when the cam rotates, when the tappet is collapsed at least a predetermined amount and the chamber is not filled;
• wherein when the chamber contains more than a pre-determined amount of fluid the tappet is actuated such that the EGR valve is at least partially opened and the cam is removed from mechanical communication with the piston.

A dual mode EGR system for use on a combustion engine having an intake line and a compressor, the EGR system comprising:

• an EGR passage having at least one aperture that opens into the intake line downstream of the compressor;
• an EGR valve that blocks flow through the EGR passage when closed,
• an actuator coupled to the EGR valve, and adapted to operate in at least a first mode and a second mode, the actuator comprising:
• a cylinder;
• a piston disposed within the cylinder and coupled to the EGR valve;
• a spring disposed to bias the EGR valve in a closed position;
• a spool valve comprising:
• a spool;
• a sleeve;
• a high-pressure reservoir;
• a low-pressure reservoir;
• an intermediate chamber disposed to be in direct fluid communication with the high-pressure reservoir when the spool is in a first position, to be in direct fluid communication with the low-pressure reservoir when the spool is in a second position, and to be out of direct fluid communication with both the high-pressure and low-pressure reservoirs when the spool is in a third position;
• at least one solenoid disposed to move the spool between the first, second, and third positions;
• wherein the intermediate chamber is in direct fluid communication with the cylinder;
• wherein the spool valve actuates the EGR valve by causing fluid to flow into and out of the cylinder by placing the cylinder into direct fluid communication with the high-pressure reservoir and the low-pressure reservoir, respectively.
• wherein when the engine operates near torque peak the actuator functions in the first mode by placing the spool in the third position.

A three-way spool valve, comprising:

• a sleeve having an axis, and a first aperture, a second aperture, and a third aperture;
• a spool disposed within the sleeve so as to be able to move within the sleeve between at least a first, second, and third position, the waist of the spool and the sleeve defining an intermediate chamber;
• a high-pressure reservoir in direct fluid communication with the first aperture;
• a low-pressure reservoir in direct fluid communication with the second aperture;
• a control reservoir positioned within the sleeve adjacent to a first end of the spool, in direct fluid communication with the high-pressure reservoir through a narrow aperture, the control reservoir having a closable large aperture, such that the pressure in the control reservoir can be altered by opening and closing the closable large aperture, whereby a force on the spool in a first axial direction created by the pressure in the control reservoir can likewise be altered;
• a return reservoir positioned within the sleeve adjacent to a second end of the spool in direct fluid communication with the low-pressure reservoir;
• a spring positioned within the return reservoir to oppose motion of the spool in the first axial direction created by the pressure in the control reservoir at least when the second end of the spool has moved in the first axial direction past a first predetermined point along the axis;
• wherein the first and third apertures are positioned to be in direct fluid communication with the intermediate chamber when the spool is in the first position;
• and
• wherein the second and third apertures are positioned to be in direct fluid communication with the intermediate chamber when the spool is in the second position.