Systems and methods for counter flow management and valve motion sequencing in enhanced engine braking

Patent metadata

Field	Value
Publication number	US-2019040802-A1
Application number	US-201816054701-A
Country	US
Kind code	A1
Filing date	Aug 3, 2018
Priority date	Aug 3, 2017
Publication date	Feb 7, 2019
Grant date	—

Abstract

Systems and methods for managing excessive intake flow path pressure and counter flow are implemented to support enhanced engine braking applications, such as 2-stroke or 1.5-stroke engine braking implementations where the intake flow path may be exposed to excessive transient pressures in the combustion chamber during activation or deactivation of an engine brake. Intake throttle, exhaust gas recirculation (EGR) valve, intake manifold blow-off valve, compressor bypass valve, exhaust throttle, turbocharger geometry or turbocharger waste gate may be controlled to effectuate counter flow management separately or in combination. Excessive transient conditions may also be prevented or managed by sequential valve motion in which brake motion activation occurs first and then exhaust valve main event deactivation occurs second. Delay between brake activation and main event deactivation may be facilitated using mechanical and/or hydraulic implements as well as electronically.

First claim

What is claimed is:

1 . A method for controlling counter flow and pressure in an intake flow path of an internal combustion engine during an engine braking operation, the internal combustion engine comprising at least one cylinder, an intake flow path communicating with the at least one cylinder, at least one intake valve disposed in the intake flow path, an exhaust flow path communicating with the at least one cylinder and at least one exhaust valve disposed in the exhaust flow path, the method comprising:
deactivating main event motion of the at least one exhaust valve; activating a braking motion of the at least one exhaust valve; and managing counter flow in the intake flow path with at least one airflow management device disposed in at least one of the intake flow path or the exhaust flow path.

2 . The method of claim 1 , wherein the airflow management device includes an exhaust gas recirculation valve in communication with the intake flow path and the exhaust flow path, the exhaust gas recirculation valve providing a first level of communication between the intake flow path and the exhaust flow path during steady-state engine braking operation, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the exhaust gas recirculation valve to increase communication between the intake flow path and the exhaust flow path above the first level of communication.

3 . The method of claim 1 , wherein the airflow management device comprises an intake throttle valve disposed in the intake flow path, the intake throttle providing a first level of flow in the intake flow path during steady state engine braking operation, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the intake throttle valve to restrict flow in the intake flow path below the first level of flow.

4 . The method of claim 1 , wherein the airflow management device comprises a turbocharger in communication with the intake flow path and the exhaust flow path, a turbine of the turbocharger configured to provide a first level of boost pressure in the intake flow path during steady state engine braking operation, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the turbine to decrease boost pressure in the intake flow path below the first level of boost pressure.

5 . The method of claim 1 , wherein the airflow management device comprises a turbocharger in communication with the intake flow path and the exhaust flow path and a wastegate in communication with the exhaust flow path, the wastegate and the turbocharger configured to provide a first level of boost pressure in the intake flow path during steady state engine braking operation, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the wastegate to decrease boost pressure provided by the turbocharger in the intake flow path below the first level of boost pressure.

6 . The method of claim 1 , wherein the airflow management device comprises a turbocharger in communication with the intake flow path and the exhaust flow path and an exhaust throttle valve in the exhaust flow path, the exhaust throttle valve and the turbocharger configured to provide a first level of boost pressure in the intake flow path during steady state engine braking operation, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the exhaust throttle valve to decrease boost pressure provided by the turbocharger in the intake flow path below the first level of boost pressure.

7 . The method of claim 1 , wherein the airflow management device comprises a turbocharger in communication with the intake flow path and the exhaust flow path and a compressor bypass valve in communication with the intake flow path, the compressor bypass valve and the turbocharger configured to provide a first level of boost pressure in the intake flow path during steady state engine braking operation, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the compressor bypass valve to decrease boost pressure provided by the turbocharger in the intake flow path below the first level of boost pressure.

8 . The method of claim 1 , wherein the airflow management device comprises a passive blow-off valve in communication with the intake flow path, and wherein managing counterflow in the intake flow path further comprises:
configuring the passive blow-off valve to open when pressure within in the intake flow path exceeds a predetermined threshold.

9 . The method of claim 1 , wherein the airflow management device comprises an active blow-off valve in communication with the intake flow path, and wherein managing counterflow in the intake flow path further comprises:
no later than deactivation of the main event motion of the at least one exhaust valve, controlling the active blow-off valve to open.

10 . A method for controlling counter flow and pressure in an intake flow path of an internal combustion engine during an engine braking operation, the internal combustion engine comprising a plurality of cylinders, an intake flow path communicating with the plurality of cylinders and an exhaust flow path communicating with the plurality of cylinders, each cylinder of the plurality of cylinders having at least one intake valve disposed in the intake flow path and at least one exhaust valve disposed in the exhaust flow path, the method comprising:
initiating engine braking operation for a first group of cylinders from the plurality of cylinders, the first group of cylinders including less than all of the plurality of cylinders, wherein initiating engine braking operation comprises:
for each cylinder in the first group of cylinders, deactivating main event motion of the at least one exhaust valve;
for each cylinder in the first group of cylinders, activating a braking motion of the at least one exhaust valve;
after expiry of a period of time following initiating engine braking operation for the first group of cylinders, initiating engine braking operation for a second group of cylinders from the plurality of cylinders, the second group of cylinders including at least one cylinder not included in the first group of cylinders, wherein initiating engine braking operation comprises:
for each cylinder in the second group of cylinders, deactivating main event motion of the at least one exhaust valve;
for each cylinder in the second group of cylinders, activating a braking motion of the at least one exhaust valve.

Assignees

• Jacobs Vehicle Systems Inc

Inventors

• Lilly Ryan
• Alexandru Matei
• Baltrucki Justin D

Classifications

• F01L2820/01

  Absolute values · CPC title

• F01L1/08

  Shape of cams · CPC title

• F01L1/20

  Adjusting or compensating clearance · CPC title

• F01L2305/00

  Valve arrangements comprising rollers · CPC title

• F01L1/181

  Centre pivot rocking arms · CPC title