Diagnostic method and apparatus for monitoring the wear of at least an engine timing chain

Diagnostic device for monitoring wear of a continuously circulating chain in a chain drive of an engine which, from a crankshaft drives at least one camshaft and in the course of the chain drive engages in the teeth of at least two mutually spaced chain sprockets, said device having a sensor positioned adjacent a chain sprocket and having a signal processing unit to which the sensor emits signals in interaction with the chain drive, the signal processing device comparing the signals with a desired value signal and, when there is a deviation from this signal, emitting a signal indicative of unacceptable wear in the form of an unacceptable lengthening of the chain, wherein:

• an engine-integrated diagnostic device monitors wear of the chain during engine operation in a no contact manner;
• the diagnostic device contains at least two sensors arranged on different chain sprockets;
• at least one marker is mounted on each of the respective chain sprockets, which marker triggers a sensor signal in one of said sensors at least once per rotation of the respective chain sprocket, said signal representing an angular position of the chain sprockets with respect to one another;
• the signal processing device contains means for determining a phase relation of the received sensor signals with respect to one another, means for performing a desired value comparison with respect to the phase relation, and a signal generator which, when the phase relation deviates from the predetermined desired value, emits a signal reporting a lengthening of the timing chain;
• and
• a function module integrated into the signal processing device determines maximal and minimal values from a value sequence of all phase relations sensed in the detection per at least one chain circulation and, for each respective value sequence, forms the difference between the maximal and minimal values.

Method for monitoring wear of a continuously circulating chain of an engine by comparing signals from a chain sprocket of a chain drive circuit indicative of running of the chain in said circuit, with a predetermined desired value, and recognizing an unacceptable wear of said chain in the form of an unacceptable lengthening of the chain, when there is a deviation from this desired value, said method comprising the steps of:

• during engine operation, determining an actual relative phase relation between signals of two engine-integrated on-board sensors which detect angular position of different chain sprockets of the chain drive circuit;
• comparing said actual relative phase relation with a predetermined desired value;
• and
• if the actual phase relation deviates from the desired value, generating a signal which indicates an unacceptable lengthening of the timing chain;
• wherein said step of generating a signal comprises:
• in the case of a singular or multiple, but not permanent occurrence of a deviation of the actual relative phase relation from the desired value during a timing chain circulation, generating a signal which indicates an unacceptable lengthening of the timing chain due to damage to an individual link.

Method for monitoring wear of a continuously circulating chain of an engine by comparing signals from a chain sprocket of a chain drive circuit indicative of running of the chain in said circuit, with a predetermined desired value, and recognizing an unacceptable wear of said chain in the form of an unacceptable lengthening of the chain, when there is a deviation from this desired value, said method comprising the steps of:

• during engine operation, determining an actual relative phase relation between signals of two engine-integrated on-board sensors which detect angular position of different chain sprockets of the chain drive circuit;
• comparing said actual relative phase relation with a predetermined desired value;
• and
• if the actual phase relation deviates from the desired value, generating a signal which indicates an unacceptable lengthening of the timing chain;
• wherein all phase relations are detected within at least one circulation of said chain in said chain drive circuit, forming a sequence of values;
• and
• wherein the sequence of values is compared with a desired value, and an approximately permanent falling of the values below the desired value is indicative of an unacceptably high overall chain wear.

Method for monitoring wear of a continuously circulating chain of an engine by comparing signals from a chain sprocket of a chain drive circuit indicative of running of the chain in said circuit, with a predetermined desired value, and recognizing an unacceptable wear of said chain in the form of an unacceptable lengthening of the chain, when there is a deviation from this desired value, said method comprising the steps of:

• during engine operation, determining an actual relative phase relation between signals of two engine-integrated on-board sensors which detect angular position of different chain sprockets of the chain drive circuit;
• comparing said actual relative phase relation with a predetermined desired value;
• and
• if the actual phase relation deviates from the desired value, generating a signal which indicates an unacceptable lengthening of the timing chain;
• wherein all phase relations are detected within at least one circulation of said chain in said chain drive circuit, forming a sequence of values;
• and
• wherein said step of generating a signal comprises:
• determining a maximal and a minimal value from said sequence of values;
• determining a difference between the maximal and minimal values;
• comparing said difference with a desired value;
• and
• generating a signal indicative of an exceeding of the difference above this desired value as a signal for an unacceptably high individual-link wear.

Method for monitoring wear of a continuously circulating chain of an engine by comparing signals from a chain sprocket of a chain drive circuit indicative of running of the chain in said circuit, with a predetermined desired value, and recognizing an unacceptable wear of said chain in the form of an unacceptable lengthening of the chain, when there is a deviation from this desired value, said method comprising the steps of:

• during engine operation, determining an actual relative phase relation between signals of two engine-integrated on-board sensors which detect angular position of different chain sprockets of the chain drive circuit;
• comparing said actual relative phase relation with a predetermined desired value;
• and
• if the actual phase relation deviates from the desired value, generating a signal which indicates an unacceptable lengthening of the timing chain;
• wherein all phase relations are detected within at least one circulation of said chain in said chain drive circuit, forming a sequence of values;
• and
• wherein said step of generating a signal comprises:
• comparing the sequence of values with a predetermined value sequence pattern indicating a specific wear condition of the timing chain;
• and
• in the case of a periodically repeated correspondence of the value sequence and the pattern, emitting a signal which indicates a type or degree of the wear of the timing chain according to the wear condition contained in the pattern.

Diagnostic device for monitoring wear of a continuously circulating chain in a chain drive of an engine which, from a crankshaft drives at least one camshaft and in the course of the chain drive engages in the teeth of at least two mutually spaced chain sprockets, said device having a sensor positioned adjacent a chain sprocket and having a signal processing unit to which the sensor emits signals in interaction with the chain drive, the signal processing device comparing the signals with a desired value signal and, when there is a deviation from this signal, emitting a signal indicative of unacceptable wear in the form of an unacceptable lengthening of the chain, wherein:

• an engine-integrated diagnostic device monitors wear of the chain during engine operation in a no contact manner;
• the diagnostic device contains at least two sensors arranged on different chain sprockets;
• at least one marker is mounted on each of the respective chain sprockets, which marker triggers a sensor signal in one of said sensors at least once per rotation of the respective chain sprocket, said signal representing an angular position of the chain sprockets with respect to one another;
• the signal processing device contains means for determining a phase relation of the received sensor signals with respect to one another, means for performing a desired value comparison with respect to the phase relation, and a signal generator which, when the phase relation deviates from the predetermined desired value, emits a signal reporting a lengthening of the timing chain;
• and
• the signal processing device contains means for performing a pattern recognition which compares detected value sequence of the phase relations with a predetermined value sequence pattern indicating a specific wear condition of the timing chain;
• and
• in the case of a periodically repeated correspondence of the value sequence and the pattern the signal processing unit emits a signal reporting type or the degree or the wear of the timing chain according to the wear condition contained in the pattern.

A method of detecting deformation of a chain which circulates continuously about at least two sprockets in an engine, said method comprising the steps of:

• measuring a rotational relative phase relation of said first and second sprockets while said engine is running;
• repeating said measuring step for a plurality of iterations during at least a complete circulation of said chain on said sprockets, whereby a series of measured values is generated;
• determining minimum and maximum values from among measured values in said series of measured values;
• determining a difference between said maximum and minimum values;
• comparing said difference with a predetermined value;
• and
• when said difference exceeds said predetermined value, generating a signal indicative of excessive wear of a portion of said chain.

A method of detecting deformation of a chain which circulates continuously about at least two sprockets in an engine, said method comprising the steps of:

• measuring a rotational relative phase relation of said first and second sprockets while said engine is running;
• repeating said measuring step for a plurality of iterations during at least a complete circulation of said chain on said sprockets, whereby a series of measured values is generated;
• determining a maximum value from among measured values in said series of measured values;
• comparing said maximum value with a predetermined value;
• and
• when said maximum value exceeds said desired value, generating a signal indicative of excessive overall chain wear.

Apparatus for monitoring wear of a chain which circulates continuously about at least first and second sprockets in an engine, comprising:

• a first sensor for generating a first signal indicative of rotational position of said first sprocket;
• a second sensor for generating a second signal indicative of rotational position of said second sprocket;
• means far comparing said first and second signals to determine a relative rotational phase relation of said first and second sprockets at a plurality of points within at least a complete circulation of said chain on said sprockets, whereby a series of measured values is generated;
• means for determining minimum and maximum values from among measured values in said sequence of measured values;
• means for determining a difference between said minimum and maximum values;
• means for comparing said difference with a predetermined value;
• and
• means for generating a signal indicative of excessive wear of a portion of said chain whenever said difference exceeds said predetermined value.

Apparatus for monitoring wear of a chain which circulates continuously about at least first and second sprockets in an engine, comprising:

• a first sensor for generating a first signal indicative of rotational position of said first sprocket;
• a second sensor for generating a second signal indicative of rotational position of said second sprocket;
• means for comparing said first and second signals to determine a relative rotational phase relation of said first and second sprockets at a plurality of points within at least a complete circulation of said chain on said sprockets, whereby a series of measure values is generated;
• means for determining a maximum value from among said series of measured values;
• means for comparing said maximum value with a predetermined value;
• and
• means for generating a signal indicative of excessive overall chain wear when said maximum value exceeds said predetermined value.