초록 ▼

A preferred embodiment EGR valve permits exhaust gas to be induced into the intake line downstream of the compressor, while minimizing the need to reduce the size of the turbocharger. The preferred embodiment EGR valve exploits variations around the mean pressure in the EGR passage created by the en

A preferred embodiment EGR valve permits exhaust gas to be induced into the intake line downstream of the compressor, while minimizing the need to reduce the size of the turbocharger. The preferred embodiment EGR valve exploits variations around the mean pressure in the EGR passage created by the engine cycle by selectively opening when the pressure in the EGR valve exceeds the pressure in the intake line. Thus, exhaust gas is recirculated even when the engine is running near torque peak. The preferred embodiment EGR valve also exploits the higher mean pressure in the exhaust line relative to the intake line at higher engine speeds by remaining open, in order to minimize the energy consumed in opening and closing the EGR valve.

대표청구항 ▼

1. 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; an EGR valve coupled to the slave piston and biased in a closed position

1. 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; an EGR valve coupled to the slave piston and biased in a closed position: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. 2. The EGR system of claim 1, wherein the EGR valve is biased with a spring.3. The EGR system of claim 1, wherein the at least one hydraulic master cylinder is actuated by at least one rocker arm of the engine.4. The EGR system of claim 1, wherein the at least one hydraulic master cylinder is actuated by at least one cam follower of the engine.5. An EGR system for use on an internal combustion engine, theEGR 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. 6. The EGR system of claim 5, further comprising:a bleed line having at least one aperture in the slave cylinder, the aperture being positioned to be uncovered only when the piston is at one extreme of its range of motion. 7. An EGR system, comprising: a EGR valve biased in a closed position; a piston coupled to the EGR valve; a cam at least able to be in mechanical communication with the piston, such that when the cam rotates the piston is actuated, wherein the cam is in contact with the piston, such that the cam is always in mechanical communication with the piston while the cam is operating; and; a motor coupled to the cam.8. An EGR system, comprising:a EGR valve biased in a closed position; a piston coupled to the EGR valve; a cam at least able to be in mechanical communication with the piston, such that when the cam rotates the piston is actuated, wherein the cam is in contact with the piston, such that the cam is always in mechanical communication with the piston while the cam is operating, further comprising: a variable tappet that places the cam and piston in mechanical communication when the tappet is at least partially collapsed. 9. The EGR system of claim 8, further comprising:a chamber in contact with the tappet; a fill line adapted to direct hydraulic fluid into the chamber; wherein the EGR valve is at least partially opened and the cam is removed from mechanical communication with the piston when the chamber contains more than a pre-determined amount of fluid. 10. An EGR system, comprising:a EGR valve biased in a closed position; a piston coupled to the EGR valve; a cam at least able to be in mechanical communication with the piston, such that when the cam rotates the piston is actuated, wherein the cam is in contact with the piston, such that the cam is always in mechanical communication with the piston while the cam is operating, further comprising: a chamber in contact with the tappet; a fill line adapted to direct hydraulic fluid into the chamber; wherein the EGR valve is at least partially opened and the cam is removed from mechanical communication with the piston when the chamber contains more than a pre-determined amount of fluid. 11. 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, wherein the actuator comprises only a single coil. 12. 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. 13. The dual mode EGR system of claim 12, wherein the actuator operates in the second mode only when a mean pressure in the EGR passage is less than a mean pressure in the intake line near the at least one aperture.14. The dual mode EGR system of claim 12, wherein the actuator comprises a single-coil three-way spool valve.15. The dual mode EGR system of claim 12, wherein the actuator comprises:a EGR valve biased in a closed position; a piston coupled to the EGR valve; a cam at least able to be in mechanical communication with the piston, such that when the cam rotates the piston is actuated. 16. The dual mode EGR system of claim 15, wherein the cam is in contact with the piston, such that the cam is always in mechanical communication with the piston while the cam is operating.17. The dual mode EGR system of claim 16, further comprising a motor coupled to the cam.18. The dual mode EGR system of claim 15, further comprising a variable tappet that places the cam and piston in mechanical communication when the tappet is collapsed by at least a pre-determined amount.19. The dual mode EGR system of claim 18, further comprising:a chamber in contact with the tappet; a fill line adapted to direct hydraulic fluid into the chamber; wherein the EGR valve is at least partially opened and the cam is removed from mechanical communication with the piston when the chamber contains more than a pre-determined amount of fluid. 20. The dual mode EGR system of claim 12, wherein the actuator operates in the second mode when the engine is operating near torque peak.21. The dual mode EGR system of claim 20, wherein the actuator opens the EGR valve only when a pressure in the EGR passage is greater than a pressure in the intake line near the at least one aperture.22. The dual mode EGR system of claim 20, wherein the actuator comprises a spool valve.23. The dual mode EGR system of claim 20, wherein the actuator comprises a single-coil three-way spool valve.24. The dual mode EGR system of claim 20, wherein the actuator comprises:at least one hydraulic master cylinder; a slave cylinder in fluid communication with the hydraulic master cylinder and having a slave piston, the slave cylinder is coupled to the EGR valve; and wherein the EGR valve is biased in a close position. 25. The dual mode EGR system of claim 24, wherein the EGR valve is biased with a spring.26. The dual mode EGR system of claim 24, wherein the at least one hydraulic master cylinder is actuated by at least one rocker arm of the engine.27. The dual mode EGR system of claim 24, wherein the at least one hydraulic master cylinder is actuated by at least one cam follower of the engine.28. The dual mode EGR system of claim 24, wherein the actuator comprises: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. 29. The dual mode EGR system of claim 28, further comprising:a bleed line having at least one aperture in the slave cylinder, the aperture being positioned to be uncovered only when the piston is at one extreme of its range of motion. 30. 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. 31. The dual mode EGR system of claim 30, wherein the three-port control valve is placed in the second state and the closable bypass is opened, such that the actuator functions in the second mode when a mean pressure in the EGR passage is less than a mean pressure in the intake line near the at least one aperture.32. The dual mode EGR system of claim 30, wherein the three-port control valve is placed in the second state and the closable bypass is opened, such that the actuator functions in the second mode only when a pressure in the EGR passage is greater than a pressure in the intake line near the at least one aperture.33. 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. 34. The dual mode EGR system of claim 33, wherein the motor of the actuator turns the cam at an angular velocity and angular displacement with a timing of the engine selected so as to cause the EGR valve to open and close synchronously with increases in a pressure in the EGR passage above a pressure in the intake line near the at least one aperture.35. The dual mode EGR system of claim 34, wherein the angular velocity and angular displacement are varied such that an amount of EGR is controlled.36. 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. 37. 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. 38. The dual mode EGR system of claim 37, wherein the at least one solenoid comprises fewer than two solenoids.39. The dual mode EGR system of claim 38, wherein the spool valve further comprises:a first check valve between; a second check valve; a pilot valve. 40. 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. 41. The three-way spool valve of claim 40, further comprising:a first check valve; a second check valve; wherein the first and third apertures are in checked fluid communication through the first check valve, the first check valve being biased to permit flow therethrough from the third aperture to the first aperture; wherein the second and third apertures are in checked fluid communication through the second check valve, the second check valve being biased to permit flow therethrough from the second aperture to the third aperture. 42. The three-way spool valve of claim 40,wherein the pressure in the low-pressure reservoir is sufficient to substantially prevent cavitation; wherein the pressure in the high-pressure reservoir is sufficient to generate a force in the first axial direction sufficient to overcome a force in the second axial direction generated by the pressure in the low-pressure reserve plus a force generated by the spring at maximum compression. 43. The three-way spool valve of claim 40, further comprising:a first positive stop positioned to prevent the spool from travelling past the first position in a second axial direction; a second positive stop positioned to prevent the spool from travelling past the second position in the first axial direction. 44. The three-way spool valve of claim 43,wherein the first positive stop comprises a stop ring having a diameter less than a diameter of the spool, the stop ring being affixed to the sleeve, and wherein the second positive stop comprises a hub disposed within the return reservoir, the return reservoir having an annular hip of a greater diameter than the rest of the reservoir, the hub extending radially into the annular hip.