Engine including camshaft with lobe features for internal exhaust gas recirculation

Patent metadata

Field	Value
Publication number	US-9541010-B2
Application number	US-201213547354-A
Country	US
Kind code	B2
Filing date	Jul 12, 2012
Priority date	Jul 12, 2012
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

An engine assembly includes a camshaft having an exhaust cam lobe defining an exhaust lift region and an exhaust base circle region and an EGR cam lobe defining an EGR lift region and an EGR base circle region. The EGR lift region is rotationally offset from the exhaust lift region and the EGR base circle region is rotationally aligned with the exhaust lift region. An exhaust valve lift mechanism is engaged with an exhaust valve, the exhaust cam lobe and the EGR cam lobe and is operable in first and second modes. The exhaust valve remains closed when the EGR lift region engages the exhaust valve lift mechanism during the second mode and the exhaust valve is opened when the EGR lift region engages the exhaust valve lift mechanism during the first mode to provide exhaust gas flow into the combustion chamber during an intake stroke of the combustion chamber.

First claim

What is claimed is:

1. An engine assembly comprising:
an engine structure defining a first combustion chamber and first exhaust port in communication with the first combustion chamber;
a first exhaust valve located in the first exhaust port;
a camshaft including:
a first exhaust cam lobe defining a first exhaust lift region and a first exhaust base circle region; and
a first EGR cam lobe defining a first EGR lift region and a first EGR base circle region that extends continuously from an end of the first EGR lift region to a start of the first EGR lift region in a rotational direction of the first EGR cam lobe, the first EGR lift region being rotationally offset from the first exhaust lift region in the rotational direction of the camshaft and the first EGR base circle region being rotationally aligned with the first exhaust lift region; and

a first exhaust valve lift mechanism supported by the engine structure, engaged with the first exhaust cam lobe and the first EGR cam lobe and operable in first and second modes, the first exhaust valve remaining closed when the first EGR lift region engages the first exhaust valve lift mechanism during the second mode and the first exhaust valve being opened when the first EGR lift region engages the first exhaust valve lift mechanism during the first mode to provide exhaust gas flow into the first combustion chamber during an intake stroke of the first combustion chamber, wherein the first exhaust valve lift mechanism includes a first arm engaged with the first exhaust valve and the first exhaust cam lobe and a second arm independent from and coupled to the first arm and engaged with the first EGR cam lobe, the second arm being rotatable relative to the first arm during the second mode and being fixed for rotation with the first arm during the first mode, wherein the first arm includes a roller member engaged with the first exhaust cam lobe and the second arm includes a slider interface that engages the first EGR lift region of the first EGR cam lobe, wherein during rotation of the camshaft, the EGR base circle region of the EGR cam lobe is free from contact with the exhaust valve lift mechanism so that the base circle region is always radially offset from the second arm and the engagement between the EGR cam lobe and the exhaust valve lift mechanism is limited to the EGR lift region.

2. The engine assembly of claim 1 , further comprising a second exhaust valve, a second exhaust valve lift mechanism engaged with the second exhaust valve and an oil control valve in fluid communication with the first and second exhaust valve lift mechanisms, the engine structure defining a second combustion chamber and a second exhaust port in communication with the second combustion chamber and the camshaft defining a second exhaust cam lobe and a second EGR cam lobe, the second exhaust valve lift mechanism being engaged with the second exhaust cam lobe and the second EGR cam lobe and being operable in the first and second modes with the second exhaust valve remaining closed when a second EGR lift region of the second EGR cam lobe engages the second exhaust valve lift mechanism during the second mode and the second exhaust valve being opened when the second EGR lift region engages the second exhaust valve lift mechanism during the first mode to provide exhaust gas flow into the second combustion chamber during an intake stroke of the second combustion chamber.

3. The engine assembly of claim 2 , wherein the oil control valve switches operation of the first and second exhaust valve lift mechanisms between the first and second modes with the first and second exhaust valve lift mechanisms both being operated in either the first mode or the second mode.

4. The engine assembly of claim 3 , wherein a firing order of the engine assembly includes the first combustion chamber having a combustion event immediately subsequent to a combustion event in the second combustion chamber.

5. The engine assembly of claim 1 , further comprising an intake valve located in an intake port defined in the engine structure in communication with the first combustion chamber, an intake valve lift mechanism engaged with the intake valve and an intake cam lobe engaged with the intake valve lift mechanism and including an intake lift region and an intake base circle region with the first EGR lift region being rotationally aligned with the intake lift region.

6. The engine assembly of claim 5 , wherein an entirety of the first EGR lift region is rotationally aligned with the intake lift region.

7. The engine assembly of claim 1 , wherein an exhaust valve lift provided by the first EGR lift region is between 20 percent and 60 percent of an exhaust valve lift provided by the first exhaust lift region.

8. The engine assembly of claim 1 , further comprising an exhaust system including an exhaust conduit in communication with the exhaust port, an intake system including a turbocharger in communication with an intake port defined in the engine structure and the exhaust conduit, and an EGR line extending from the exhaust conduit at a location between the turbocharger and an outlet of the exhaust conduit to the intake system and providing communication between the intake and the exhaust system.

9. The engine assembly of claim 8 , further comprising a backpressure control valve in the exhaust conduit at a location between the EGR line and the outlet of the exhaust conduit.

10. An engine assembly comprising:
an engine structure defining first and second combustion chambers, a first exhaust port in communication with the first combustion chamber and a second exhaust port in communication with the second combustion chamber;
a first exhaust valve located in the first exhaust port and a second exhaust valve located in the second exhaust port;
a camshaft including:
a first exhaust cam lobe defining a first exhaust lift region;
a first EGR cam lobe defining a first EGR lift region and a first EGR base circle region extending continuously from an ending point of the first EGR lift region to a starting point of the first EGR lift region in a rotational direction of the camshaft;
a second exhaust cam lobe defining a second exhaust lift region; and
a second EGR cam lobe defining a second EGR lift region and a second EGR base circle region extending continuously from an ending point of the second EGR lift region to a starting point of the second EGR lift region in the rotational direction of the camshaft;

a first exhaust valve lift mechanism supported by the engine structure, engaged with the first exhaust cam lobe and the first EGR cam lobe and operable in first and second modes, the first exhaust valve remaining closed when the first EGR lift region engages the first exhaust valve lift mechanism during the second mode and being opened when the first EGR lift region engages the first exhaust valve lift mechanism during the first mode to provide exhaust gas flow into the first combustion chamber during an intake stroke of the first combustion chamber, wherein the first exhaust valve lift mechanism includes a first arm engaged with the first exhaust valve and the first exhaust cam lobe and a second arm independent from and coupled to the first arm and engaged with the first EGR cam lobe, the second arm being rotatable relative to the first arm during the second mode and being fixed for rotation with the first arm during the first mode;
a second exhaust valve lift mechanism supported by the engine structure, engaged with the second exhaust cam lobe and the second EGR cam lobe and operable in the first and second modes, the second exhaust valve remaining closed when the second EGR lift region engages the second exhaust valve lift mechanism during the se

Assignees

• Gonzalez Delgado Manuel Angel
• Dean Charles
• Moon Joseph J
• Gm Global Tech Operations Llc

Inventors

• Gonzalez Delgado Manuel Angel
• Dean Charles
• Moon Joseph J

Classifications

• F02D13/0273 Primary

  Multiple actuations of a valve within an engine cycle · CPC title

• Y02T10/18

  Cross-Sectional Technologies · mapped topic

• F01L1/267

  with means for varying the timing or the lift of the valves · CPC title

• F02M26/01

  Internal exhaust gas recirculation, i.e. wherein the residual exhaust gases are trapped in the cylinder or pushed back from the intake or the exhaust manifold into the combustion chamber without the use of additional passages · CPC title

• F01L2800/10

  Providing exhaust gas recirculation [EGR] · CPC title