Control of piston trajectory in a linear generator

Patent metadata

Field	Value
Publication number	US-11053876-B2
Application number	US-202016910673-A
Country	US
Kind code	B2
Filing date	Jun 24, 2020
Priority date	Mar 31, 2016
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

Various embodiments of the present disclosure are directed towards free-piston combustion engines. As described herein, a method and system are provided for displacing a free-piston assembly to achieve a desired engine performance by repeatedly determining position-force trajectories over the course of a propagation path and effecting the displacement of the free-piston assembly based, at least in part, on the position-force trajectory. In a dual-piston assembly free-piston engine, synchronization of the two piston assemblies is provided.

First claim

What is claimed is:

1. A method performed by a programmed computer system for controlling displacement of opposed free-piston assemblies, the method comprising:
determining, using a control system, a first position-force trajectory for a first free-piston assembly of the opposed free-piston assemblies;
determining, using the control system, a second position-force trajectory for a second free-piston assembly of the opposed free-piston assemblies;
calculating a first synchronization force for the first free-piston assembly;
calculating a second synchronization force for the second free-piston assembly; and
effecting displacement of the first free-piston assembly and the second free-piston assembly based on the first position-force trajectory, the second position-force trajectory, the first synchronization force, and the second synchronization force.

2. The method of claim 1 , wherein the first free-piston assembly and the second free-piston assembly cycle between respective apices defining two strokes, the method further comprising:
producing net electrical energy output over both of the two strokes using a linear electromagnetic machine.

3. The method of claim 1 , wherein effecting displacement of the first free-piston assembly and the second free-piston assembly comprises regulating a difference between a position of the first free-piston assembly and a position of the second free-piston assembly.

4. The method of claim 1 , wherein effecting displacement of the first free-piston assembly and the second free-piston assembly comprises synchronizing apices of the first free-piston assembly with apices of the second free piston assembly.

5. The method of claim 1 , wherein the first synchronization force and the second synchronization force are opposite forces.

6. The method of claim 1 , wherein:
a) the first position-force trajectory comprises a force to apply to the first free-piston assembly based on a current position of the first free-piston assembly and a target position without regard to a deviation from a previously determined trajectory;
b) cause the force to be applied to the first free-piston assembly for a first time interval; and
c) repeating a) and b) until the first free-piston assembly reaches at least one of the target position or an apex position.

7. The method of claim 6 , wherein the target position comprises a desired apex position.

8. The method of claim 6 , wherein a) comprises determining the force based at least in part on an estimated pressure in a compression section in contact with the first free-piston assembly.

9. The method of claim 6 , further comprising:
d) determining a new target position of the first free-piston assembly;
e) determining a new force to apply to the first free-piston assembly based on a new current position of the first free-piston assembly and the new target position; and
f) causing the new force to be applied to the first free-piston assembly for a second time interval.

10. The method of claim 6 , further comprising:
d) determining a new force to apply to the first free-piston assembly based on a new current position of the first free-piston assembly and the target position; and
e) determining not to apply the new force to the first free-piston assembly for a second time interval if the current position is outside of a cut-off position threshold.

11. A system comprising:
a first free-piston assembly;
a second free-piston assembly opposite the first free-piston assembly; and
a control system configured to:
determine a first position-force trajectory for the first free-piston assembly,
determine a second position-force trajectory for the second free-piston assembly,
calculate a first synchronization force for the first free-piston assembly,
calculate a second synchronization force for the second free-piston assembly, and
effect displacement of the first free-piston assembly and the second free-piston assembly based on the first position-force trajectory, the second position-force trajectory, the first synchronization force, and the second synchronization force.

12. The system of claim 11 , wherein:
the first free-piston assembly and the second free-piston assembly cycle between respective apices defining two strokes; and
the control system is configured to cause net electrical energy output over both of the two strokes using a linear electromagnetic machine.

13. The system of claim 11 , wherein the control system is configured to effect the displacement of the first free-piston assembly and the second free-piston assembly by regulating a difference between a position of the first free-piston assembly and a position of the second free-piston assembly.

14. The system of claim 11 , wherein the control system is configured to effect the displacement of the first free-piston assembly and the second free-piston assembly by synchronizing apices of the first free-piston assembly with apices of the second free piston assembly.

15. The system of claim 11 , wherein the first synchronization force and the second synchronization force are opposite forces.

16. The system of claim 11 , wherein
the control system is further configured to:
a) determine the first position-force trajectory by determining a force to apply to the first free-piston assembly based on a current position of the first free-piston assembly and a target position without regard to a deviation from a previously determined trajectory;
b) cause the force to be applied to the first free-piston assembly for a first time interval; and
c) repeat a) and b) until the first free-piston assembly reaches at least one of the target position or an apex position.

17. The system of claim 16 , wherein the target position comprises a desired apex position.

18. The system of claim 16 , wherein the control system is further configured to repeat a) and b) by:
repeatedly determining a new force to apply to the first free-piston assembly based on a new current position of the first free-piston assembly and the target position; and
repeatedly causing the new force to be applied to the first free-piston assembly for respective time interval.

19. The system of claim 16 , wherein the control system is further configured to:
d) determine a new target position of the first free-piston assembly;
e) determine a new force to apply to the first free-piston assembly based on a new current position of the first free-piston assembly and the new target position; and
f) cause the new force to be applied to the first free-piston assembly for a second time interval.

20. The system of claim 16 , wherein the control system is further configured to:
d) determine new a force to apply to the first free-piston assembly based on a new current position of the first free-piston assembly and the target position; and
e) determine not to apply the new force to the first free-piston assembly for a second time interval if the current position is outside of a cut-off position threshold.

Assignees

• Mainspring Energy Inc

Inventors

• Roelle Matthew
• Gadda Christopher

Classifications

• F02D41/1402

  Adaptive control · CPC title

• F02D29/06

  peculiar to engines driving electric generators · CPC title

• F02D41/009

  using means for generating position or synchronisation signals · CPC title

• F02B63/04

  for electric generators · CPC title

• F02D35/024

  using an estimation · CPC title