Diagnostic method and arrangement for quantitatively checking actuators in internal combustion engines

• US 4,794,790 A
• Filed: 07/17/1987
• Issued: 01/03/1989
• Est. Priority Date: 07/19/1986
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Margarit-Metaxa, Florin, Denz, Helmut
• Primary Examiner(s): Levy, Stewart J.
• Assistant Examiner(s): Raevis, Robert R.
• Application Number:
  US07/074,897
• Time in Patent Office: 536 Days
• Field of Search: 73/117.3, 73/117.2, 73/118.1, 73/168, 73/119 R, 364/551
• US Class Current: 73/114.39
• CPC Class Codes: F02D 35/0007 using electrical feedback F02D35/0015 takes precedence
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

A diagnostic method and arrangement quantitatively checks actuators during the open-loop and/or closed-loop control of operational parameters of an internal combustion engine. The method and arrangement checks the idle actuator and the tank venting value well as the associated hardward chains, that increased or decreased quantities of air (±ΔQ_TEV/LLR) be supplied via an appropriate controlling to the tank-venting valve or of the idle regulator, preferbly simultaneously and in opposite directions and that the resulting possible changes of rotational speed (rotational speed remains constant; rotational speed decreases; rotational speed increases) be determined and appropriately evaluated.

Claims

1. A diagnostic method for quantitatively checking actuators in the open-loop and closed loop control of operating parameters of an internal combustion engine which includes:

a fuel metering apparatus;

an air-flow sensor; and

, a central control unit including computer units; and

, an exhaust system accommodating a lambda control, the actuators including the idle actuator and tank-venting valve (TEV) for effecting a tank ventilation, said actuators having respective hardware chains, the method comprising the steps of;

supplying increased or reduced air quantities (Δ

Q_TEV, Δ

Q_LLR) by means of a corresponding control of one of the tank-venting valve (TEV) and the idle actuator (LLS) during the operation of the engine; and

,

observing feedback of rotational speed changes which occur (rotational speed n=constant;

n_Diagn >

n_alt ; and

, n_Diagn <

n_alt) to provide an indication as to the functioning capability of the hardware chains of said actuators wherein;

n_Diagn is the diagnosed speed of the engine; and

,

n_alt is the engine prior to starting the diagnosis.

2. The diagnostic method of claim I, wherein an increased air quantity (Δ

Q_TEV) is supplied by opening the tank-venting valve and simultaneously therewith, a correspondingly decreased air quantity (-Δ

Q_LLR) is supplied by closing the idle actuator with the particular air quantities (Δ

Q) being held equal, so that the total air flow remains constant and so that subsequently the rotational speed which remains substantially constant, the actuators with the respective hardware chains associated therewith are judged as operating correctly and, with an increase in rotational speed, the idle actuator is recognized as being defective and, with a reduction in rotational speed, the tank-venting valve is recognized as being defective.

3. Arrangement for performing a quantitative self-diagnosis of actuators in the open-loop and closed loop control of operating parameters of an internal combustion engine, the actuators including idle actuator (LLS) and tank-venting valve (TEV), the arrangement comprising:

supply means for supplying an increased air quantity or reduced air quantity [(Δ

Q_TEV/LLR)](Δ

Q_TEV, Δ

Q_LLR) to the inlet region of the internal combustion engine by means of a corresponding control of said actuators;

comparison means for comparing the speed of the engine prior to the air flow change with a diagnosed rotational speed; and

,

indication means for indicating a defect in response to a speed change of one of the tank-venting valve n_Diagn <

n_alt -Δ

n_Tol) and the idle actuator (n_Diagn >

n_alt +Δ

n_Tol) wherein;

n_Diagn is the diagnosed speed of the engine;

n_alt is the engine speed prior to starting the diagnosis; and

,

Δ

n_Tol is the tolerance of rotational speed deviation (engine constant value, to be ascertained during application).