Gas engine

Patent metadata

Field	Value
Publication number	US-2016222902-A1
Application number	US-201414897509-A
Country	US
Kind code	A1
Filing date	May 28, 2014
Priority date	Jun 11, 2013
Publication date	Aug 4, 2016
Grant date	—

Abstract

A gas engine is provided to control an air-fuel ratio in response to changes in composition of fuel gas. A gas engine 1 includes: an A/F valve 22 ; a solenoid valve 21 ; and a control unit 10 configured to perform perturbation using the solenoid valve 21 and set a relationship between an air-fuel ratio and respective opening degrees of the solenoid valve 21 and the A/F valve 22 under a specific engine operation condition using standard fuel gas. During an actual operation in a period in which the engine operation condition is deemed to be stable, when an opening-degree average value b of the solenoid valve 21 deviates from an opening-degree target value a of the solenoid valve 21 set in the control unit 10 under the above operation condition, the control unit 10 adjusts the opening degree of the A/F valve 22 so that the opening-degree average value b equals the opening-degree target value a.

First claim

1 . (canceled)

2 . A gas engine comprising:
a first valve and a second valve, the first valve having a responsiveness being lower and a fuel flow rate adjustment range being wider than the second valve, and the second valve having a responsiveness being higher and a fuel flow rate adjustment range being narrower than the first valve; and a control unit configured to perform perturbation using the second valve by moving the second valve from a predetermined opening degree to a lean side or a rich side while the first valve is being opened at a predetermined opening degree, wherein, during an actual operation in a period in which an operation condition of the engine is deemed to be stable, when an opening-degree average value of the second valve deviates from an opening-degree target value of the second valve, the opening-degree target value being set in the control unit under the operation condition, the control unit is configured to adjust the opening degree of the first valve so that the opening-degree average value equals the opening-degree target value, by calculating the opening-degree average value by extracting a maximum opening degree and a minimum opening degree according to opening degrees detected at positions where a signal from an oxygen sensor disposed on an upstream side of an exhaust passage relative to a catalyst passes through a set point in the perturbation control by the second valve during the actual operation.

3 . (canceled)

4 . The gas engine according to claim 2 , wherein the control unit adjusts the opening degree of the first valve so that the opening degree converges into the opening-degree target value with a certain range.

5 . The gas engine according to claim 2 , wherein the first valve and the second valve are disposed with respect to each cylinder head or with respect to a group of cylinder heads.

6 . The gas engine according to claim 2 , wherein a plurality of the first valves and/or the second valves is disposed.

7 . (canceled)

8 . A gas heat pump system including the gas engine according to claim 2 as a drive source.

9 . A cogeneration system including the gas engine according to claim 2 as a drive source.

Assignees

• Yanmar Co Ltd

Inventors

• Otsubo Hiroyuki
• Kishio Kazuma

Classifications

• F02M21/047

  Venturi mixer · CPC title

• F02D41/1408

  Dithering techniques · CPC title

• F02D41/1454 Primary

  the characteristics being an oxygen content or concentration or the air-fuel ratio · CPC title

• F02D19/023

  to adjust the fuel mass or volume flow · CPC title

• F02D41/1441

  Plural sensors · CPC title