Method for detecting slip in generator and starter generator systems

• US 20030155772A1
• Filed: 04/10/2003
• Published: 08/21/2003
• Est. Priority Date: 03/15/2001
• Status: Active Grant

• Current Assignee: Seg Automotive Germany GMBH
• Original Assignee: Robert Bosch GmbH
• Inventors: Beck, Markus, Scherrbacher, Klaus
• Granted Patent: US 7,102,246 B2
• Time in Patent Office: Days
• US Class Current: 290/40B
• CPC Class Codes: F02B 67/06 driven by means of chains, belts, or like endless members
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: F02N 15/025 of the friction type
• CPC Class Codes: F02N 15/10 Safety devices not otherwise provided for
• CPC Class Codes: H02P 9/02 Details of the control

Abstract

The invention is based on a method for detecting slip in the driving of generator or starter-generator systems. The alternators of these systems are equipped with electronic control components such as pulse-width-modulated inverters or rectifier bridges. The drive torque of the alternator is transferred to this by means of a belt drive of an internal combustion engine. When slip is detected in a comparison step (3), to which speed-dependent input variables (1, 2) are forwarded, the maximum transferrable drive torque is determined in a torque limiting step (18, 20), and a closed-loop control (23) adjusts the generator output power to said maximum transferrable drive torque.

Claims

1. A method for detecting slip (4) in the driving of alternators that are controlled with an electronic machine control such as a pulse-width-modulated inverter or a rectifier, and in the case of which the drive torque is transferred from an internal combustion engine to the alternator via a belt drive,

wherein, when slip (4) s is detected in a comparison step (3), to which speed-dependent input variables (1, 2) are forwarded, a signal (9) is generated, so that the maximum transferrable drive torque is determined in a torque limiting step (18, 20), and a closed-loop control (23) adjusts the generator output power to said maximum transferrable drive torque.

2. The method according to claim 1,

wherein the input variables are the alternator speed (1) n_Gen and the rotational speed of the crankshaft of the internal combustion engine (2) n_KW.

3. The method according to claim 2,

wherein the slip (4) s is determined in the comparison step (3) according to the relationship

$\frac{(n_{\mathrm{kw}}·}{}$

u¨

-nGen)nkw·

u¨

=s

with ü

=pulley ratio.

4. The method according to claim 1,

wherein the instantaneous slip value (4) s is checked if it exceeds a maximum permissible, pre-settable slip value (6) s.

5. The method according to claim 4,

wherein, when the maximum permissible slip value (6) s_max is exceeded, the determined instantaneous slip (4) s is chronologically filtered and checked for plausibility, and a status bit (9) is set as the signal.

6. The method according to claim 5,

wherein the status bit (9) is entered as a fault entry (13) in a fault memory (12) that can be read out via a diagnostics unit.

7. The method according to claim 1,

wherein, depending on the signal (9), the maximum permissible torque (15) is set to a reduced torque (16) in a first speed limiting step (18).

8. The method according to claim 7,

wherein, during an acceleration phase of the internal combustion engine

$(\frac{}{}$

nkw

t)>

0,

the reduced torque (16) of a second limiting step (20) is also limited.

9. The method according to claims 7 and 8,

wherein the output variable (16) of the first torque limiting step (18) [and] the output variable (22) of the second torque limiting step (20) are combined at a summing point (19).

10. The method according to claim 9,

wherein the output variable (16) and the output variable (22), with signs, are added at a summing point (19).

11. The method according to claim 9,

wherein the variable resulting at the summing point (19) represents the reduced, maximum permissible drive torque of the alternator to which the generator output power is adjusted via a closed-loop control (23).