Control method for combustion system, combustion system, and diesel engine

Patent metadata

Field	Value
Publication number	US-12180904-B2
Application number	US-202218290406-A
Country	US
Kind code	B2
Filing date	Jan 21, 2022
Priority date	Jun 17, 2021
Publication date	Dec 31, 2024
Grant date	Dec 31, 2024

Abstract

In a control method for the combustion system, spatial intensities of entrainment effects in a cylinder of fuel sprays of the two injections can be superimposed by means of two main fuel injections, two organizations of the fuel sprays for a flow field in the cylinder are implemented; by determining a duration and a first injection pressure of first main fuel injection, a cylinder pressure can at least reach an upper limit threshold of the cylinder pressure; and during second main fuel injection, in a time period when the cylinder pressure drops from the upper limit threshold of the cylinder pressure to a set cylinder pressure, a change rate of the curve slope of a cylinder pressure change curve at each time point is within a set range of slope change rates, and a rotation angle of a crankshaft is not smaller than a first preset rotation angle.

First claim

The invention claimed is:

1. A method for controlling a combustion system, wherein the combustion system comprises a piston, an injector, and a cylinder, the piston is configured to reciprocate up and down in the cylinder, the injector is configured to execute at least a first main fuel injection and a second main fuel injection in sequence during each movement cycle of the piston, and the injector is configured to continuously inject fuel during a process from the first main fuel injection to the second main fuel injection; an injection pressure when a velocity of the fuel injected by the injector is highest during the first main fuel injection executed by the injector is a first injection pressure, and an injection pressure when a velocity of the fuel injected by the injector is highest during the second main fuel injection executed by the injector is a second injection pressure;
the method for controlling a combustion system comprising:
determining a duration of the first main fuel injection and the first injection pressure to allow a cylinder pressure to reach a cylinder pressure upper threshold at least at partial moment during the first main fuel injection; and
iteratively adjusting at least one of a duration of the second main fuel injection and the second injection pressure, to allow a change rate of curve slopes of a cylinder pressure change curve during a period when the cylinder pressure drops from the cylinder pressure upper threshold to a set cylinder pressure to be within a set range of slope change rates at any time point, and to allow an angle that a crankshaft has rotated during the period when the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure to be not less than a first preset rotation angle in the second main fuel injection.

2. The method for controlling a combustion system according to claim 1 , wherein that determining the duration of the first main fuel injection and the first injection pressure to allow the cylinder pressure to reach the cylinder pressure upper threshold at least at partial moment during the first main fuel injection comprises:
iteratively adjusting at least one of a start time and an end time of the first main fuel injection, and current first injection pressure until the cylinder pressure reaches the cylinder pressure upper threshold at least at partial moment during the first main fuel injection, a crankshaft angle when the cylinder pressure reaches the cylinder pressure upper threshold for a first time does not exceed a first angle, and an angle that the crankshaft has rotated during a period when the cylinder pressure rises from the first cylinder pressure to the cylinder pressure upper threshold is not less than a second preset rotation angle, in a case that the cylinder pressure never reaches the cylinder pressure upper threshold during the first main fuel injection; wherein a cylinder volume when the cylinder pressure is equal to the first cylinder pressure is the same as a cylinder volume when the cylinder pressure reaches the cylinder pressure upper threshold for the first time.

3. The method for controlling a combustion system according to claim 2 , wherein during each movement cycle of the piston, a timing when the injector starts the first main fuel injection is a first time t 1 , a timing when a velocity of the fuel injected by the injector is lowest between the first main fuel injection and the second main fuel injection is a second time t 2 , and the first injection pressure is P 1 ;
that iteratively adjusting at least one of the start time and the end time of the first main fuel injection, and the current first injection pressure until the cylinder pressure reaches the cylinder pressure upper threshold at least at partial moment during the first main fuel injection, the crankshaft angle when the cylinder pressure reaches the cylinder pressure upper threshold for the first time does not exceed the first angle, and the angle that the crankshaft has rotated during the period when the cylinder pressure rises from the first cylinder pressure to the cylinder pressure upper threshold is not less than the second preset rotation angle, in the case that the cylinder pressure never reaches the cylinder pressure upper threshold during the first main fuel injection, comprises:
collecting the cylinder pressure P in the cylinder in real time, collecting the crankshaft angle in real time, comparing the cylinder pressure P with the cylinder pressure upper threshold P max , and determining whether the crankshaft angle exceeds the first angle, during the first main fuel injection; and
increasing the first injection pressure P 1 , and/or, wholly reducing a difference between the second time t 2 and the first time t 1 , if the cylinder pressure P is less than the cylinder pressure upper threshold P max , and the crankshaft angle is behind the first angle.

4. The method for controlling a combustion system according to claim 3 , wherein the increasing the first injection pressure P 1 , and/or, wholly reducing the difference between the second time t 2 and the first time t 1 comprises:
acquiring a maximum value P x of the cylinder pressure during the first main fuel injection;
calculating n=(P max −P x )/P max ; and
only increasing the first injection pressure P 1 by a first set value if n≤5%.

5. The method for controlling a combustion system according to claim 4 , wherein if n>5%, increasing the first injection pressure P 1 by the first set value, and adjusting the first time t 1 and/or the second time t 2 to wholly reduce the difference between the second time t 2 and the first time t 1 by a second set value.

6. The method for controlling a combustion system according to claim 3 , wherein
if the cylinder pressure P is not less than the cylinder pressure upper threshold P max , and the crankshaft angle is before the first angle,
acquiring a real-time cylinder volume V in the cylinder when the cylinder pressure P is equal to the cylinder pressure upper threshold P max ;
acquiring a crankshaft angle ϕ a when the cylinder goes up and a crankshaft angle ϕ b when the cylinder goes down when the cylinder volume is equal to the real-time cylinder volume V, according to a relationship map between the cylinder volume and the crankshaft angle;
calculating ϕ 1 =ϕ b −ϕ a ;
comparing ϕ 1 with the second preset rotation angle ϕ n ; and
increasing the first injection pressure P 1 by a third set value, and/or adjusting the first time t 1 and/or the second time t 2 to wholly reduce the difference between the second time t 2 and the first time t 1 by a fourth set value, in a case that ϕ 1 <ϕ n .

7. The method for controlling a combustion system according to claim 6 , wherein the second injection pressure is P 2 ; that iteratively adjusting at least one of a duration of the second main fuel injection and the second injection pressure, to allow the change rate of the curve slopes of the cylinder pressure change curve during the period when the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure to be within the set range of slope change rates at any time point, and to allow the angle that the crankshaft has rotated during the period when the cylinder pressure drops from the cylinder pressure upper threshold to the set cylinder pressure to be not less than the first preset rotation angle in the second main fuel injection comprises:
in a case that ϕ 1 ≥ϕ n ;
acquiring a crankshaft angle ϕ e when the cylinder pressure P is equal to P n according to the map, wherein ϕ c >ϕ b , P 1 is the set cylinder pressure and P max >P n ;
acquiring a relationship curve y between the cylinder pressure and the crankshaft angle in a range from the crankshaft an

Assignees

• Weichai Power Co Ltd

Inventors

• Tan Xuguang
• Zhou Peng
• Tong Dehui
• Pang Bin
• Gu Yuncheng
• Liu Xiaoxin

Classifications

• F02M45/12

  providing a continuous {cyclic} delivery with variable pressure · CPC title

• F02D2200/0602

  Fuel pressure · CPC title

• F02D41/40

  with means for controlling injection timing or duration · CPC title

• F02D35/028

  by determining the combustion timing or phasing · CPC title

• F02D41/3836

  Controlling the fuel pressure · CPC title