Method and system for engine temperature control

Patent metadata

Field	Value
Publication number	US-2016115884-A1
Application number	US-201514861857-A
Country	US
Kind code	A1
Filing date	Sep 22, 2015
Priority date	Oct 22, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

Methods and systems are provided to improve engine temperature control. Cylinders scheduled for deactivation may have their exhaust retained in the cylinder by holding an exhaust valve closed on the preceding firing cycle. In this way soot emissions on reactivation are reduced.

First claim

1 . A method for an engine, comprising:
selecting a cylinder for deactivation; and on an engine cycle immediately preceding the deactivation, maintaining an exhaust valve of the selected cylinder closed during an exhaust stroke of the cylinder.

2 . The method of claim 1 , wherein the selecting a cylinder for deactivation is responsive to a drop in engine load.

3 . The method of claim 1 , wherein during the selecting, an exhaust temperature is higher than a threshold temperature.

4 . The method of claim 1 , further comprising, during reactivation of the selected cylinder, opening the exhaust valve before opening the intake valve to release trapped exhaust gases before inducting air.

5 . The method of claim 1 , wherein opening the exhaust valve includes opening the exhaust valve during an exhaust stroke of an engine cycle immediately preceding the reactivation.

6 . The method of claim 1 , wherein the selected cylinder is a first cylinder, the method further comprising selecting a second, different cylinder for deactivation, and operating the second cylinder with one or more of a deactivated intake valve, deactivated exhaust valve, a deactivated fuel injector, deactivated spark, and delayed spark.

7 . The method of claim 6 , wherein the operating includes:
operating the second cylinder in a first mode with the intake valve opening during an intake stroke, the fuel injector deactivated, deactivated spark, and with the exhaust valve opening during an exhaust stroke; operating the second cylinder in a second mode with the intake valve opening during the intake stroke, the fuel injector activated, deactivated spark, and with the exhaust valve opening during the exhaust stroke; operating the second cylinder in a third mode with the intake valve opening during an intake stroke or a compression stroke, the fuel injector activated and fuel delivered during the compression stroke, spark deactivated, and with the exhaust valve opening during the exhaust stroke; operating the second cylinder in a fourth mode with the intake valve opening during the intake stroke, the fuel injector activated, spark delayed to the exhaust stroke, and with the exhaust valve opening during the exhaust stroke; and selecting a mode based on exhaust catalyst temperature.

8 . The method of claim 1 , further comprising, deactivating the selected cylinder for a number of engine cycles, wherein the maintaining an exhaust valve of the selected cylinder closed is responsive to the number of engine cycles being higher than a threshold number.

9 . The method of claim 7 , wherein the threshold number is based on one or more of an engine coolant temperature, an ambient temperature, and a cylinder temperature, the threshold number decreased as any of the engine coolant temperature, the ambient temperature, and the cylinder temperature decreases.

10 . A method for an engine, comprising:
deactivating a cylinder pattern of individual cylinder mechanisms, the cylinder pattern including a first deactivated cylinder and a second active cylinder, wherein in response to a command for deactivation of the first cylinder, and further based on an engine temperature, an exhaust valve of the first cylinder is held closed on an exhaust stroke of an engine cycle immediately preceding the deactivation of the first cylinder.

11 . The method of claim 10 , wherein the exhaust valve of the first cylinder held closed based on engine temperature includes the exhaust valve held closed in response to the engine temperature being lower than a threshold.

12 . The method of claim 11 , wherein the cylinder pattern further includes a number of engine cycles over which the first cylinder is maintained deactivated, the method further comprising, reactivating the first cylinder after the number of engine cycles.

13 . The method of claim 12 , wherein the engine temperature is an estimated engine temperature or an expected engine temperature, the expected engine temperature including a temperature of the engine or an engine component expected at the reactivating.

14 . The method of claim 12 , further comprising, during the reactivating, opening the exhaust valve of the first cylinder before opening the intake valve of the first cylinder to release trapped exhaust gases before inducting air into the first cylinder.

15 . The method of claim 13 , further comprising, in response to the expected engine temperature being below a threshold, operating a third cylinder with a rich fuel injection delivered during a compression stroke and spark deactivated while operating a fourth cylinder with a lean fuel injection delivered during an intake stroke and spark deactivated.

16 . An engine system, comprising:
an engine having a plurality of cylinders, each cylinder including an intake and an exhaust valve;
a deactivation mechanism for deactivating at least one of the intake valve and exhaust valve of one of the plurality of cylinders;
a temperature sensor for estimating an engine temperature; and
a controller configured with computer-readable instructions stored on non-transitory memory for:
selecting one of the plurality of cylinders for deactivation based on engine load; and
on a first engine cycle, opening the intake valve of each of the plurality of engine cylinders during respective intake strokes, holding the exhaust valve of the one of the plurality of cylinders closed during an exhaust stroke while opening the exhaust valve of remaining cylinders during respective exhaust strokes; and
on a second engine cycle, immediately following the first engine cycle, deactivating the intake valve and exhaust valve of the one of the plurality of cylinders while maintaining remaining cylinders active.

17 . The system of claim 16 , wherein the holding the exhaust valve of the one of the plurality of cylinders closed during the exhaust stroke is responsive to the engine temperature being lower than a threshold.

18 . The system of claim 17 , further comprising, operating one or more of the remaining cylinders with spark timing delayed into an exhaust stroke to raise the engine temperature above the threshold.

19 . The system of claim 17 , further comprising, operating at least one of the remaining cylinders with spark active and fuel enrichment while operating at least another of the remaining cylinders with spark active and fuel enleanment to raise the engine temperature above the threshold.

20 . The system of claim 16 , further comprising, on a third engine cycle, reactivating the exhaust valve of the one of the plurality of cylinders and opening the exhaust valve during an exhaust stroke, and during a fourth engine cycle immediately following the third engine cycle, reactivating the intake valve of the one of the plurality of cylinders and opening the intake valve during an intake stroke.

Assignees

• Ford Global Tech Llc

Inventors

• Vanderwege Brad Alan
• Glugla Chris Paul

Classifications

• F02D41/1446

  the characteristics being exhaust temperatures · CPC title

• F02D41/0087 Primary

  Selective cylinder activation, i.e. partial cylinder operation (deceleration cut-off F02D41/123) · CPC title

• F02D41/024

  to increase temperature of the exhaust gas treating apparatus · CPC title

• F02D2041/001

  for engines with variable valve actuation · CPC title

• F02P9/002

  Control of spark intensity, intensifying, lengthening, suppression (by means of current control in the storage devices F02P3/05, F02P3/09, during starting F02P15/12) · CPC title