Method and apparatus to evaluate a starter motor for an internal combustion engine

Patent metadata

Field	Value
Publication number	US-9506445-B2
Application number	US-201414168059-A
Country	US
Kind code	B2
Filing date	Jan 30, 2014
Priority date	Jan 30, 2014
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A method for monitoring the starter motor includes determining starter motor resistance associated with an engine starting event and determining a back-emf for the starter motor based upon the starter motor resistance. A state of health of the starter motor corresponding to the back-emf of the starter motor and engine cranking time is determined. Engine stop/start functionality is controlled based upon the state of health of the starter motor.

First claim

The invention claimed is:

1. A method for monitoring an electrically-powered starter motor for a starter of an internal combustion engine, comprising:
determining a starter motor resistance associated with an engine starting event;
determining a back-emf for the starter motor based upon the starter motor resistance;
determining a state of health (SOH) of the starter motor corresponding to the back-emf of the starter motor and a measured engine cranking time; and
controlling engine stop/start functionality based upon the SOH of the starter motor.

2. The method of claim 1 , wherein determining the back-emf for the starter motor based upon the starter motor resistance comprises employing the starter motor resistance to estimate back-emf in accordance with the following relationships:
y ( t )=φ( t )θ= V B ( t )− I B {circumflex over (R)} e

φ( t )= N spd ,θ=K e

wherein V B (t) is a battery voltage,
I B is a battery current,
{circumflex over (R)} e is an estimate of the starter motor resistance,
N spd is a rotational speed of the starter motor, and
K e is the estimated back-emf.

3. The method of claim 2 , wherein the estimated starter motor resistance for the starting event is determined in accordance with the following relationship:

R
^

e

=

V

m
⁢

⁢
i
⁢

⁢
n

I
p

wherein {circumflex over (R)} e is the estimated starter motor resistance,
V min is a minimum starter voltage during the starting event, and
I p is a peak starter current during the starting event.

4. The method of claim 2 , wherein employing the starter motor resistance to estimate back-emf further comprises applying a least-squares estimation routine to converge to the estimated back-emf for the battery current and the battery voltage during the engine starting event.

5. The method of claim 1 , wherein determining the SOH of the starter motor comprises determining the state of health based upon a minimum SOH of a start/stop function availability SOH and a fault detection SOH, said minimum SOH adjusted based upon a ratio of a nominal engine cranking time and the measured engine cranking time.

6. The method of claim 5 , wherein the start/stop function availability SOH is determined in accordance with the following relationship:

SOH

start
⁢

⁢
_
⁢

⁢
stop
⁢

⁢
_
⁢

⁢
avail

=

min
⁡

[

min
⁡

(

R
nom

,

R
^

e

)

max
⁡

(

R
nom

,

R
^

e

)

,

K
e

K

e
⁢

⁢
_
⁢

⁢
nom

]

wherein K e is an estimated back-emf,
K e-nom is a nominal back-emf adjusted based upon a nominal starter motor resistance adjusted for starter motor temperature T SM ,
R nom is a nominal starter motor resistance, and
{circumflex over (R)} e is an estimate of the starter motor resistance.

7. The method of claim 5 , wherein the fault detection SOH is determined in accordance with the following relationship:

SOH

fault
⁢

⁢
_
⁢

⁢
detection

=

min
⁡

[

min
⁡

(

R

adj
⁢

⁢
_
⁢

⁢
nom

Assignees

• Gm Global Tech Operations Llc

Inventors

• Ghoneim Youssef A
• Howell Mark N

Classifications

• F02N2200/063

  Battery voltage · CPC title

• F02N11/0825 Primary

  related to prevention of engine restart failure, e.g. disabling automatic stop at low battery state · CPC title

• F02N11/0814

  comprising means for controlling automatic idle-start-stop · CPC title

• F02N11/108 Primary

  for diagnosis of the starter or its components · CPC title

• F02N2200/064

  Battery temperature · CPC title