Diagnostic method for a valve drive actuator

Patent metadata

Field	Value
Publication number	US-9765659-B2
Application number	US-201314765076-A
Country	US
Kind code	B2
Filing date	Dec 11, 2013
Priority date	Feb 5, 2013
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A method for diagnosing an electromagnetic actuator of a sliding cam valve drive of an internal combustion engine. An actuator pin is released by electrical energizing of the actuator and is introduced into a groove-like sliding slot which passes through a cylindrical slot section of the associated sliding cam-and ends in a slope onto the cylindrical circumference of the slot section. The method includes: energizing the actuator using current parameters of a variable actuator characteristic map so that the actuator pin is released when the cylindrical circumference overlaps the actuator pin circumferentially; determining whether the released actuator pin generates a rejection signal due to the slope from the sliding slot onto the cylindrical circumference; if no rejection signal is detected, repeating step a) whereas at least one current parameter is changed and step b); updating the actuator characteristic map with the changed current parameter.

First claim

What is claimed is:

1. A method for diagnosing an electromagnetic actuator of a sliding cam valve train of an internal combustion engine, the actuator having at least one actuator pin, the at least one actuator pin, as a result of electrical energizing of the actuator, being released and dipping into a groove-like displacement slot passing through a cylindrical slot section of the associated sliding cam and ending, in the rotation direction of the cam, with an upward slope onto the cylindrical circumference of the slot section, the method comprising the following diagnostic steps carried out during operation of the internal combustion engine:
a) energizing the actuator with current parameters of a variable actuator characteristic map in such a way that the actuator pin is released when the cylindrical circumference overlaps the actuator pin circumferentially and a directly subsequent dip of the actuator pin into the displacement slot does not result in any displacement of the sliding cam;
b) detecting whether the released actuator pin generates in the actuator a rejection signal due to the upward slope from the displacement slot onto the cylindrical circumference;
c) if no rejection signal is detected, repeating step a) using at least one changed current parameter and step b); and
d) updating the actuator characteristic map with the changed current parameter.

2. The method as recited in claim 1 wherein the actuator has two actuator pins selectively released and dipped into a left-hand groove and a right-hand groove of the displacement slot, the left-hand and right-hand grooves, running separated from one another by the cylindrical circumference, uniting in the rotation direction of the cam to form a united groove ending with the upward slope onto the cylindrical circumference, the diagnostic step a) being carried out in such a way that the actuator pin that is released is the actuator pin in circumferential overlap with the cylindrical circumference between the left-hand and right-hand grooves.

3. The method as recited in claim 1 wherein the current parameter to be changed is a duration of energization of the actuator.

4. The method as recited in claim 3 wherein the duration of energization is changed only by the start of energization of the actuator.

5. The method as recited in claim 3 wherein, if a rejection signal is detected, steps a) and b) are repeated with a changed duration of energization as many times as necessary until a rejection signal is no longer detected, the actuator characteristic map being updated with the penultimate duration of energization.

6. The method as recited in claim 1 wherein the diagnostic steps are carried out on all actuators of the valve train.

7. The method as recited in claim 1 wherein the diagnostic steps are carried out on the actuator in different operating states of the internal combustion engine or after predetermined operating time intervals.

8. The method as recited in claim 7 wherein the different operating states include an operating temperature of the internal combustion engine and a supply voltage to the actuators.

Assignees

• Schaeffler Technologies Ag

Inventors

• Walther Christoph
• Manteufel Arne

Classifications

• F01L13/0036 Primary

  the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction · CPC title