Skip cylinder compression braking

Patent metadata

Field	Value
Publication number	US-11549455-B2
Application number	US-202016839651-A
Country	US
Kind code	B2
Filing date	Apr 3, 2020
Priority date	Apr 8, 2019
Publication date	Jan 10, 2023
Grant date	Jan 10, 2023

Abstract

An internal combustion engine operates so that it delivers zero or negative torque. The engine operates in either a deceleration cylinder cut off (DCCO) mode or skip cylinder compression braking mode. In the skip cylinder compression braking mode, selected working cycles of selected working chambers are operated in a compression release braking mode. Accordingly, individual working chambers are sometimes not fired and sometimes operated in the compression release braking mode while the engine is operating in the skip cylinder compression braking mode.

First claim

What is claimed is:

1. A method of operating an internal combustion engine having a plurality of working chambers mounted to a vehicle comprising:
receiving a zero or negative torque request;
deciding whether it is appropriate to have the internal combustion engine rotate without firing any working cycles based on an aftertreatment element temperature, or a road grade; and
if a zero or negative torque request is received and operation without firing any working cycles is appropriate, operating the internal combustion engine in a deceleration cylinder cut off mode in which minimal air is pumped through the internal combustion engine or a skip cylinder braking mode depending on the magnitude of the torque request, wherein selected working cycles of selected working chambers are operated in a compression release braking mode during operation in the skip cylinder braking mode.

2. The method of claim 1 , wherein the vehicle weight is determined by measuring a torsional speed fluctuation of a rotating component in the vehicle powertrain.

3. The method of claim 1 , wherein the internal combustion engine is a compression ignition engine or a spark ignition engine.

4. The method of claim 1 , wherein if the magnitude of the torque request is zero the internal combustion engine is operated in the deceleration cylinder cut off mode.

5. The method of claim 1 , wherein if the magnitude of the torque request is greater than zero the internal combustion engine is operated in the skip cylinder compression braking mode.

6. The method of claim 5 , further comprising operating selected working cycles of selected working chambers with the working cycle pumping.

7. The method of claim 5 , further comprising operating selected working cycles of selected working chambers with the working cycle deactivated.

8. The method of claim 5 , further comprising operating selected working cycles of selected working chambers with the working cycle deactivated and other selected working cycles of selected working chambers with the working cycles pumping.

9. The method of claim 1 , further determining a density of engine working cycles using compression release braking based on the magnitude of the negative torque request.

10. The method of claim 9 , wherein the density of engine working cycles using compression release braking increases with the magnitude of the negative torque request.

11. The method of claim 9 , wherein the density of engine working cycles using compression release braking is based at least in part on a parameter selected from a group consisting of engine speed, vehicle weight, and the presence or absence of a towed trailer.

12. The method of claim 1 , further comprising determining a pattern of the selected engine compression release braking working cycles and not fired working cycles using a first order sigma delta converter or a look-up table.

13. A method of operating an internal combustion engine having a plurality of working chambers mounted to a vehicle comprising:
receiving a zero or negative torque request;
deciding whether it is appropriate to have the internal combustion engine rotate without firing any working cycles;
if a zero or negative torque request is received and operation without firing any working cycles is appropriate, operating the internal combustion engine in a deceleration cylinder cut off mode in which minimal air is pumped through the internal combustion engine or a skip cylinder braking mode depending on the magnitude of the torque request, wherein selected working cycles of selected working chambers are operated in a compression release braking mode during operation in the skip cylinder braking mode, wherein if the magnitude of the torque request is greater than zero the internal combustion engine is operated in the skip cylinder compression braking mode; and
operating selected working cycles of selected working chambers with the working cycle deactivated and other selected working cycles of selected working chambers with the working cycles pumping, wherein a pattern of compression release braking working cycles, deactivated working cycles, and pumping working cycles is based at least in part on maintaining a turbocharger rotation rate above a threshold value.

14. A method of operating an internal combustion engine having a plurality of working chambers mounted to a vehicle comprising:
receiving a zero or negative torque request;
deciding whether it is appropriate to have the internal combustion engine rotate without firing any working cycles;
if a zero or negative torque request is received and operation without firing any working cycles is appropriate, operating the internal combustion engine in a deceleration cylinder cut off mode or a skip cylinder braking mode depending on the magnitude of the torque request, wherein selected working cycles of selected working chambers are operated in a compression release braking mode during operation in the skip cylinder braking mode; and
determining a pattern of the selected engine compression release braking working cycles and not fired working cycles using a first order sigma delta converter or a look-up table, wherein the pattern of selected compression release braking working cycles is based at least in part on the acoustic response characteristics of the exhaust system.

15. The method of claim 14 , wherein if the acoustic response characteristics of the exhaust system are modified, the vehicle undergoes a recalibration to determine patterns of the selected engine compression release braking working cycles which provides acceptable noise levels.

16. An engine controller for an internal combustion engine having a plurality of working chambers mounted to a vehicle and capable of operating either in a deceleration cylinder cut off mode or a skip cylinder braking mode, the engine controller comprising:
an operational skip fire profile module arranged to determine whether it is appropriate to have the internal combustion engine rotate without firing any working cycles, wherein if it is determined that operation without firing any working cycles is appropriate, the operational skip fire profile module uses a magnitude of a torque request to decide whether to direct the internal combustion engine to operate in a deceleration cylinder cut off mode in which minimal air is pumped through the internal combustion engine or a skip cylinder braking mode, wherein selected working cycles of selected working chambers are operated in a compression release braking mode during operation in the skip cylinder braking mode, wherein if the magnitude of the torque request is greater than zero the internal combustion engine is operated in the skip cylinder compression braking mode and wherein if the magnitude of the torque request is zero or negative the internal combustion engine is operated in the deceleration cylinder cut off mode.

17. The engine controller of claim 16 , wherein the internal combustion engine is a turbocharged, compression-ignition engine.

18. The engine controller of claim 16 , wherein the operational skip fire profile module receives a plurality of input signals to help determine whether operation without firing any working cycles is appropriate, wherein the input signals are selected from a group consisting of:
(a) an accelerator pedal position;
(b) a brake pedal position;
(c) an engine speed;
(d) an aftertreatment element temperature;
(e) a turbocharger rotational speed;
(f) a transmission gear setting;
(g) a regulation covering the use of compression release braking at the vehicle's current

Assignees

• Tula Technology Inc
• Cummins Inc

Inventors

• Carlson Steven E
• Serrano Louis J
• Wilcutts Mark A
• Srinivasan Vijay

Classifications

• F02D2200/701

  Information about vehicle position, e.g. from navigation system or GPS signal · CPC title

• F02D41/3058

  the engine working with a variable number of cycles · CPC title

• F02D13/06

  Cutting-out cylinders · CPC title

• F02D2200/50

  said parameters being related to the vehicle or its components · CPC title

• F02D2200/101

  Engine speed · CPC title