Method and arrangement for determining the internal resistance of a lambda probe and for the closed-loop heating control with the aid of the internal resistance
First Claim
1. A computer-implemented method for controlling heating of a lambda probe equipped with heater control and having a temperature dependent actual internal resistance RS, said method including the steps of:
- (a) comparing the probe voltage US to a predetermined threshold Umin below which the actual internal resistance value can no longer be reliably determined and determining said actual internal resistance value when said probe voltage US is higher than said threshold Umin ;
(b) forming a variable imaginary internal resistance value by incrementally increasing an initial internal resistance value in steps by a pregiven difference value Δ
RS while assuming that said initial resistance value matches said actual internal resistance value when said probe voltage US falls below said threshold Umin ;
(c) obtaining a control deviation value Δ
Ri by forming the difference of said variable imaginary internal resistance value and a predetermined desired internal resistance value corresponding to a desired probe temperature when said probe voltage US is less than said threshold Umin or by forming the difference of the determined actual internal resistance value and said predetermined desired internal resistance value when said probe voltage US is higher than said threshold Umin ;
(d) forming an actuating variable from control deviation value Δ
Ri for said heater control; and
,(e) applying said actuating variable to the probe to control the heating.
1 Assignment
0 Petitions
Accused Products
Abstract
The internal resistance of a lambda probe is determined by: the application of a clocked direct-current counter voltage to the probe via a series resistor; the measurement of the output voltages with the counter voltage connected and disconnected; and, the calculation of the internal resistance from the measured values and known resistance values.
Apart from the components of a conventional arrangement, this method requires only a series resistor and a switch for implementation. Measurement can be carried out at short time intervals without excessively high direct-current voltage loading which affects the service life.
The internal resistance measured is compared with a desired resistance and the control deviation determined in this way is used to determine the duty factor for probe heating clocked with fixed frequency.
-
Citations
6 Claims
-
1. A computer-implemented method for controlling heating of a lambda probe equipped with heater control and having a temperature dependent actual internal resistance RS, said method including the steps of:
-
(a) comparing the probe voltage US to a predetermined threshold Umin below which the actual internal resistance value can no longer be reliably determined and determining said actual internal resistance value when said probe voltage US is higher than said threshold Umin ; (b) forming a variable imaginary internal resistance value by incrementally increasing an initial internal resistance value in steps by a pregiven difference value Δ
RS while assuming that said initial resistance value matches said actual internal resistance value when said probe voltage US falls below said threshold Umin ;(c) obtaining a control deviation value Δ
Ri by forming the difference of said variable imaginary internal resistance value and a predetermined desired internal resistance value corresponding to a desired probe temperature when said probe voltage US is less than said threshold Umin or by forming the difference of the determined actual internal resistance value and said predetermined desired internal resistance value when said probe voltage US is higher than said threshold Umin ;(d) forming an actuating variable from control deviation value Δ
Ri for said heater control; and
,(e) applying said actuating variable to the probe to control the heating. - View Dependent Claims (2, 3, 4, 5, 6)
-
Specification