Engine torque smoothing

• US 10,436,133 B2
• Filed: 07/18/2018
• Issued: 10/08/2019
• Est. Priority Date: 01/12/2015
• Status: Active Grant

• Current Assignee: Tula Technology, Incorporated
• Original Assignee: Tula Technology, Incorporated
• Inventors: Pirjaberi, Mohammad R., Eisazadeh-Far, Kian, Carlson, Steven E., Serrano, Louis J.
• Primary Examiner(s): Vo, Hieu T
• Application Number:
  US16/038,622
• Publication Number:
  US 20180320615A1
• Time in Patent Office: 447 Days
• CPC Class Codes: F02D 2041/0012 with selective deactivation of cylinders
• CPC Class Codes: F02D 41/0002 Controlling intake air
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/1498 measuring engine roughness
• CPC Class Codes: F02D 41/3058 the engine working with a variable number of cycles
• CPC Class Codes: F02D 41/307 to avoid torque shocks
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods, devices, estimators, controllers and algorithms are described for estimating the torque profile of an engine and/or for controlling torque applied to a powertrain by one or more devices other than the engine itself to manage the net torque applied by the engine and other device(s) in manners that reduce undesirable NVH. The described approaches are particularly well suitable for use in hybrid vehicles in which the engine is operated in a skip fire or other dynamic firing level modulation manner—however they may be used in a variety of other circumstances as well. In some embodiments, the hybrid vehicle includes a motor/generator that applies the smoothing torque.

Claims

1. A control system configured to control the transition of an engine between different firing fractions in a hybrid vehicle having an internal combustion engine and an additional power source/sink, the control system comprising:

an engine control unit configured to direct operation of the engine, including directing the transition of the engine from a first operational firing fraction to a target firing fraction that is different than the first operational firing fraction, and determining a firing sequence that facilitates the transition between the first operational firing fraction and the target firing fraction;

a torque profile estimator configured to determine an engine torque profile associated with the firing sequence; and

an additional power source/sink controller configured to determine a smoothing torque based at least in part of the determined engine torque profile and to direct the additional power source/sink to apply the smoothing torque during the transition from the first operational firing fraction.

2. A control system as recited in claim 1 wherein the smoothing torque is arranged to cause a predicted net powertrain torque to not exceed a threshold instantaneous torque throughout the transition.

3. A control system as recited in claim 1 wherein the smoothing torque is a filtered version of the torque profile.

4. A method of controlling the transition of an engine between different firing fractions in a hybrid vehicle having an internal combustion engine and an additional power source/sink, the method comprising:

while the engine is operating at a first firing fraction, determining a second target firing fraction that is different than the first firing fraction;

determining a firing sequence to transition between the first firing fraction and the second firing fraction;

determining an engine torque profile associated with the firing sequence;

determining a smoothing torque based at least in part of the determined engine torque profile; and

during the transition from the first firing fraction to the second target firing fraction applying the smoothing torque using the additional power source/sink.

5. A method as recited in claim 4 wherein the smoothing torque is arranged to cause a predicted net powertrain torque to not exceed a threshold instantaneous torque throughout the transition.

6. A method as recited in claim 4 wherein the smoothing torque is a filtered version of the torque profile.

7. A control system for controlling a powerplant including an engine having a crankshaft and an accessory selected from the group consisting of an alternator and an air conditioner compressor, the control system comprising:

an engine control unit configured to direct operation of the engine in a dynamic firing level modulation mode;

a torque profile modeling module configured to determine an expected torque profile associated with a sequence of one or more firing opportunities; and

an additional power source/sink controller configured to control the accessory to directly or indirectly apply a varying load on the crankshaft based at least in part on the expected torque profile.

8. A control system as recited in claim 7 wherein the additional power source/sink controller is configured to apply the varying load in a manner that reduces a magnitude of driveline vibration.

9. A control system as recited in claim 7 wherein the additional power source/sink controller is configured to synchronized the varying load with the variations in the expected torque profile over the course of an engine cycle in a manner that reduced net torque variations applied to a drive train by a combination of the engine and the accessory over the course of the engine cycle during operation in the dynamic firing level modulation mode.

10. A control system as recited in claim 9 wherein the varying load is arranged to cause a predicted net powertrain torque applied by the engine and the accessory to not exceed a threshold instantaneous torque.

11. A method of controlling a powerplant including an engine having a crankshaft and an accessory selected from the group consisting of an alternator and an air conditioner compressor, the method comprising:

operating an engine in a dynamic firing level modulation mode;

determining an expected torque profile associated with a sequence of one or more firing opportunities; and

controlling the accessory to directly or indirectly apply a varying load on the crankshaft based at least in part on the expected torque profile.

12. A method as recited in claim 11 wherein the varying load is applied in a manner that reduces a magnitude of driveline vibration.

13. A method as recited in claim 11 wherein the varying load is synchronized with the variations in the expected torque profile over the course of an engine cycle in a manner that reduced net torque variations applied to a drive train by a combination of the engine and the accessory over the course of the engine cycle during operation in the dynamic firing level modulation mode.

14. A method as recited in claim 13 wherein the varying load is arranged to cause a predicted net powertrain torque applied by the engine and the accessory to not exceed a threshold instantaneous torque.