METHOD AND SYSTEM FOR DIAGNOSING AND/OR CONTROLLING A RECIPROCATING ENGINE HAVING A VARIABLE COMPRESSION RATIO

• US 20190316517A1
• Filed: 05/31/2017
• Published: 10/17/2019
• Est. Priority Date: 05/31/2016
• Status: Active Grant

• Current Assignee: AVL List GmbH (List Privatstiftung)
• Original Assignee: AVL List GmbH (List Privatstiftung)
• Inventors: WILLIAMS, Philip
• Granted Patent: US 11,421,587 B2
• Time in Patent Office: Days
• CPC Class Codes: F01B 31/14 Changing of compression ratio
• CPC Class Codes: F02B 75/04 Engines with variable distances between pistons at top dead-centre positions and cylinder heads
• CPC Class Codes: F02D 15/00 Varying compression ratio
• CPC Class Codes: F02D 15/02 by alteration or displacement of piston stroke
• CPC Class Codes: F02D 15/04 by alteration of volume of compression space without changing piston stroke
• CPC Class Codes: F02D 2200/1012 Engine speed gradient
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: F02D 41/2429 Methods of calibrating or learning
• CPC Class Codes: F16F 15/22 Compensation of inertia forces suppression of vibrations of rotating systems by favourable grouping or relative arrangements of the moving members of the system or systems F16F15/20, counterweights F16F15/28; correcting-weights for balancing rotating bodies F16F15/32

Abstract

The invention relates to a method for diagnosing and/or controlling a reciprocating engine having a variable compression ratio, wherein the method comprises the working steps: determining (S30) a first value (U_1,1, U_1,2; Δ₁) of a rotational irregularity parameter of a crankshaft (1) of the reciprocating engine; and determining (S60) a value of a compression ratio parameter for the reciprocating engine based on said first rotational irregularity parameter value.

Claims

1. A method of diagnosing or controlling a reciprocating piston engine with a variable compression ratio, comprising:

determining a first value of a rotational irregularity parameter of a crankshaft of the reciprocating piston engine; and

determining a value of a compression ratio parameter for the reciprocating piston engine on the basis of the first value of the rotational irregularity parameter.

2. The method according to claim 1, further comprising:

changing a target compression ratio of at least a first cylinder of the reciprocating piston engine from a first target compression ratio to a second target compression ratio;

determining the first value of the rotational irregularity parameter of the crankshaft for the first target compression ratio;

determining a second value of the rotational irregularity parameter of the crankshaft for the second target compression ratio; and

determining the value of the compression ratio parameter on the basis of the first and second values of the rotational irregularity parameter.

3. The method according to claim 2, wherein changing the target compression ratio further comprises:

changing a target length of a piston rod of the first cylinder of the reciprocating piston engine.

4. The method according to claim 2, further comprising:

determining at least one of first value and the second value of the rotational irregularity parameter for an unfired operation of the first cylinder of the reciprocating piston engine.

5. The method according to claim 2, further comprising:

detecting at least one of a crank angle of the crankshaft and at least one time derivative of the crank angle; and

determining at least one of the first value and the second value of the rotational irregularity parameter on the basis of the detected crank angle or the at least one time derivative of the crank angle.

6. The method according to claim 5, further comprising:

filtering at least one or the detected crank angle and the at least one time derivative of the crank angle; and

determining the first value or the second value of the rotational irregularity parameter on the basis of the filtered crank angle or the at least one filtered time derivative.

7. The method according to claim 2, further comprising:

determining at least one of the first value and the second value of the rotational irregularity parameter for at least one specified crank angle region.

8. The method according to claim 7, wherein the at least one specified crank angle region comprises at least one of:

a top dead center of the first cylinder;

a bottom dead center of the first cylinder; and

extends over from at least 2°

to at most 135°

.

9. The method according to claim 2, wherein at least one of the first value and the second value of the rotational irregularity parameter is determined on the basis of at least one average value or at least one extreme value.

10. The method according to claim 1, further comprising:

outputting a signal if the value of the compression ratio parameter satisfies a specified condition.

11. A system for diagnosing or controlling a reciprocating piston engine with a variable compression ratio, comprising:

means for determining a first value of a rotational irregularity parameter of a crankshaft of the reciprocating piston engine; and

means for determining a value of a compression ratio parameter for the reciprocating piston engine on the basis of the first value of the rotational irregularity parameter.

12. A motorized vehicle, comprising:

a reciprocating piston engine with a variable compression ratio that includes a first cylinder coupled to a crankshaft by a piston rod having an adjustable length; and

a system for controlling the reciprocating piston engine which includes;

means for determining a first value of a rotational irregularity parameter of the crankshaft, and

means for determining a value of a compression ratio parameter for the reciprocating piston engine on the basis of the first value of the rotational irregularity parameter.