GB2572751A

GB2572751A - Method of detecting engine valve timing by accelerometers on fuel injectors

Info

Publication number: GB2572751A
Application number: GB1805459.3A
Authority: GB
Inventors: Nilsson Andreas
Original assignee: Delphi Technologies IP Ltd
Current assignee: Borgwarner US Technologies LLC
Priority date: 2018-04-03
Filing date: 2018-04-03
Publication date: 2019-10-16
Also published as: GB201805459D0

Abstract

Disclosed is an internal combustion engine having one or more cylinders, each cylinder having a fuel injector adapted to inject fuel into the cylinder, each injector having an accelerometer associated with it. A method of determining the closing time of an exhaust valve and/or inlet valve of a cylinder is disclosed, the method comprising the steps of obtaining a signal from one or more of the accelerometers, analysing the signal(s) to identify a pulse associated with the closing of either the intake valve and/or the outlet valve of the cylinder and determining the timing of the pulse(s). The accelerometer may be a knock sensor and may be used to derive other data such the timing of fuel injection and valve opening times.

Description

METHOD OF DETECTING ENGINE VALVE TIMING BY ACCELEROMETERS ON FUEL INJECTORS

TECHNICAL FIELD

This disclosure relates to a method of determining the timing of valve events, in internal combustion engines, in particular with engines where one or more fuel injectors is equipped with, or has an accelerometer, associated with the fuel injector. It has particular, but not exclusive, application to determining the intake valve and/or exhaust valve closing times with respect to one or more cylinders.

BACKGROUND OF THE INVENTION

Modern engines have variable valve timing, whereby the point in the engine cycle where the exhaust valves and inlet valves open and close is adjusted by an actuator.

It is useful to provide feedback on this adjustment (i.e. having altered the valve timing using the actuator); in particular it is useful to see how much the timing has changed. This feedback is useful either as the primary means of controlling the actuator to achieve a desired valve timing or it can be used as a diagnostic method to check that the Variable Valve Timing system is operating correctly (diagnostics are useful to meet emissions regulations).

To provide this feedback it is usual to add sensors specifically to detect the valve timing but this is expensive and requires extra wires to connect the sensors to a controller.

It is known to have accelerometers (knock sensors) associated with fuel injectors (i.e. located on or adjacent to a fuel injector) in order to provide an engine controller e.g. ECU with valuable (feedback) data concerning the operation of these fuel injectors such as vibrational data in respect of the injector valve opening and closing events such as needle opening and closing. There is usually provided communication means, such as the use of additional or existing wiring, for the accelerometer to communicate data to an ECU. In some case the injectors have processors (chips) that allow the accelerometer data to be processed such that processed data and parameters can be sent to the ECU.

It is an object of the invention to use determine intake and outlet valve closing events and hence valve timing without the use of additional components.

SUMMARY OF THE INVENTION

In one aspect is provided In an internal combustion engine having one or more cylinders, each cylinder having a fuel injector adapted to inject fuel there into, and where said injector includes an accelerometer associated therewith, a method of determining the closing time of an exhaust valve and or inlet valve of a cylinder comprising:

a) obtaining a signal from one or more of said accelerometers;

b) analysing said signal(s) and identifying a pulse associated with the closing of either the intake valve and/or the outlet valve of said cylinder from said signal(s),

c) determining the timing of said pulse(s) of step c).

The method may including performing the additional step of:

d) determining the time of a first injection with respect to said cylinder and the time of the next second injection, and step b) comprises

i) identifying one or more intermediate pulses on said accelerometer signal with respect to said cylinder between these times; and ii) identifying said one or more intermediate pulses as intake valve closing and/or the outlet valve closing events with respect to that cylinder.

Step d) may be performed from ECU or other engine data.

Step d) may be performed by identifying dominant regular pulses from said accelerometer signal.

The method may include determining the timing of two intermediate pulses having the largest magnitude between the times of step d) and taking the first as the exhaust valve closing time and/or the second as the intake valve closing events for the respective cylinder on which the accelerometer signal is determined.

The method may include identifying any intermediate pulse which is determined to be an injection event in another cylinder, and in step (i) excluding said pulse in the determination.

The accelerometer pulses may be analysed in terms of their duration, relative timing, magnitude or frequency spectra in order to classify pulses as due to any one of the following: injection, intake valve closing and outlet valve closing.

The method may including applying frequency analysis to said pulse (s) to distinguish between two or more of the following cylinder events of injection, intake valve closing and outlet valve closing.

The method may include analyzing pulses and their timing with respect to one or more accelerometers on other injectors and using this data together in step b) and or step d) additionally.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

- Figure 1 shows signals from knock sensors (accelerometers ) associated with fuel injectors during running of an engine;

- Figure 2 shows different frequency spectral content of the different events inlet valve closing, exhaust valve closing and injection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned, it is known to have accelerometers (knock sensors) associated with fuel injectors (i.e. located on or adjacent to a fuel injector) in order to provide an engine controller e.g. ECU with valuable (feedback) data. In aspects of the invention, such accelerometers are additionally used to detect (vibration of) engine (cylinder) valves opening and closing, and provide this feedback (particularly the timing of thereof) to an ECU for the purposes stated above.

Figure 1 shows signals from knock sensors (accelerometers ) associated with respective fuel injectors during running of an engine. In the example this is from a six cylinder engine. It would be understood that there may be one or more injectors have an accelerometer associated therewith. In the normal arrangement each injector may be fitted with one accelerometer. For simplicity, accelerometer signals are shown with respect to injectors for only three cylinders (cylinders A, B, C, which are adjacent to each other).

The top plots of figure 1 shows accelerometer signals in the time domain derived from each of an accelerometer on respective injector for a first, second and third cylinders A, B and C, said signals being designated 1, 2, and 3 respectively. As can be seen, pulses can be observed, designated 4, 5, and 6 on the plots, which are vibrational events with respect to injections for injectors associated with cylinders A, B and C respectively. This data is used in conventional methodology to supply feedback to the ECU on injection events. The pulses 4, 5 and 6 can be regarded as the most dominant pulses i.e. have the highest magnitude on each of the signal lines and is due to the sharp change in pressure due to combustion as seen on figure 2 which will be described hereinafter.

As can be also observed, the accelerometers associated with (e.g.) the injectors, when e g. not injecting, can also pick up other vibrational events (particularly events associated with the cylinder to which they are associated with). These events may be such as valve opening and closing events (again particularly but not exclusively in relation to valves opening and closing with respect to the cylinder with which the respective fuel injector having that accelerometer is associated with). So the vibration signals which can be particularly picked up by the accelerometers on the injectors are inlet valve closing and exhaust valve closing; these vibrational /noise events are predominantly e.g. due to the impact of when an intake valve closes or when an exhaust valve closes.

As will be explained hereinafter, accelerometers associated with an injector for a particular cylinder can also detect up vibrational events occurring with respect to other, e.g. neighbouring cylinders, such as intake and/or exhaust valve closing, and injection events. However it would be clear that the pulses detected in these respect of such events on other cylinders would be weaker.

The vibrational pulse detected on signal 1 in respect of an intake valve closing with respect to cylinder A is designated 7 and that in respect of an the exhaust valve closing with respect to cylinder A is marked 8. These pulses can be detected by the accelerometers on the injector of cylinder A and this raw data (or processed data from the raw data) sent to the ECU.

In addition, the signal 1 (in respect of accelerometer associated with fuel injector for cylinder A) also shows vibrational events/pulses (e.g. inlet and/or exhaust valve closing events) with respect to other neighbouring (e.g. adjacent) cylinders, which would obviously be of lesser magnitude than valve closing events in respect of the closing event to which the injector with that accelerometer is attached. Reference numeral 10 shows overhearing on signal 1 (accelerometer with respect to cylinder A) of the injection in cylinder C. This can be regarded as “overhearing” from events happening on adjacent cylinders. Again these lower magnitude pulses can be detected by the accelerometers and this raw data (or processed data from the raw data) sent to the ECU.

Similarly signals 2 and 3 can detect/show valve events (in particular closing events with respect to valves of the cylinder whose fuel injector/accelerometer the signals they are associated with) as well as being able to “overhear” (detect) valve events such as intake /exhaust valves closing, and injection events on other (e.g. adjacent cylinders). Reference numeral 9a shows overhearing events on signals 2 and 3 with respect to accelerometers of injectors of cylinders B ad C respectively with respect to the inlet valve closing of cylinder A, and reference numeral 9b shows overhearing events on signals 2 and 3 with respect to t accelerometers of injectors of cylinders B and C respectively with respect to the injection in cylinder A.

The term “pulse” refers to a vibrational event and should not be interpreted strictly speaking as a single oscillation but may comprise one or more oscillations over a finite time span.

Plots 11,12 and 13 show plots of pressure for respective cylinders A B and C. Plot 14 shows the respective injector drive signal.

In aspects of the invention, information derived from signals from one or more fuel injector accelerometers are used by the ECU to determine the valve opening and closing times.

The accelerometer signals may be received by the EU or alternatively where the injector include processing ability e.g. a chip associated with the injector, the injector may process the signals to and extract information from the signals and send refined data to the ECU. Either way from the signals, intake and exhaust valve closing events, particularly the times thereof with respect to the cylinders can be extracted/determined from the signals.

It would be clear that there may be many ways in which such timing data may be provided, particularly how exhaust valve closing, intake valve closing, injection and other events can be distinguished. Inferences can also be made.

With reference to one accelerometer signal with respect to its fuel injector and respective cylinder, the ECU and/or injector having a processor will be aware of the timing of the injection so it may be assumed that between the injections and thus between the pulses in respect of these injections, the dominant pulse are the exhaust valve closing and intake valve closing respectively and in that order. Alternatively the dominant pulse may be taken to be the injection pulse. In order that injection pulses with respect to other cylinders are not registered as intake exhaust valve closing events on the cylinder in question, the methodology (ECU/injector processor) may determine the injection timing in respect of other cylinders and ignore any pulses on the accelerometers (i.e. filter out these pulses),

i.e. assume they are not intake/exhaust valves closing. So in such examples each signal in respect of each accelerometer/injector/cylinder is looked at individually to determine intake and exhaust valve closing timing.

Alternatively the signals from each accelerometer (i.e. for each injector in respective cylinders) may be looked at together. For example if a vibrational pulse is detected at the same time on each signal (e.g. signals 1, 2, 3 together then ) then the magnitudes may be compared and the accelerometer (and this injector/cylinder with respect thereto) with the highest magnitude pulse may be in respect of that cylinder where the event occurs.. So in one example it can be assumed that the pulse with the highest magnitude in this case is in respect of a valve event/inj ection event for that cylinder.

Such magnitude determinations may be used even when looking at individual signals to distinguish between intake valve closing exhaust valve closing injection or other events such as looking at the shape or form of the pulse.

Other qualitative analysis may be may be made with respect to pulses on signals (such as the pulse shape) which will be explained in detail hereinafter.

Other data which may be used to distinguish between the pulses is looking at the spacing or relative spacing between pulses, also that for pulses in other cylinders. Methodology may look at the cyclic nature of pulses.

A further way of distinguishing between pulses/vibration events with respect to intake valves closing, exhaust valves closing and injection, is to analyse the frequency content of the signals e.g. analyse in the frequency domain.. The sound of inlet valve closing, exhaust valve closing and injection are all different; thus the accelerometer pulses /signals for each of these three types of event will have characteristic and different frequency content.

Figure 2 shows different frequency spectral content (magnitude versus frequency) of the different events inlet valve closing, exhaust valve closing and injection with reference numerals 20, 21 and 22 respectively; so it is be possible to determine which sound (pulse) is from which event.

The skilled person would be aware of various multitudes of processing methods used to obtain inlet and or outlet valve timing data including cross referencing between signals of other accelerometers (one example is given above), and combinations of the aforementioned techniques.

For example if there are pulses registered at the same time on a plurality of accelerometers, it can be assumed that accelerometer signal with the largest magnitude pulse of these is on the injector for the cylinder having the event which causes the pulse. Furthermore when identifying or looking for events (intake/outlet valve closing, injection) on other accelerometers the signals of lower magnitude than the largest can be discounted, i.e. ignored.

The term largest with reference to pulses means having the biggest amplitude or has the most energy and such like. It is to be noted that the term injection event in relation to a pulse can mean any pulse due to combustion consequent to injections or consequent the movement of any moving part of the inj ector.

As far as timing is concerned the accelerometers can transmit the signals to the ECU for processing and the ECU can determine the timing. Alternatively the injectors with processors can send the data with time stamps. The skilled person would be aware of the various methods where the absolute or relative timing of the pulses can be determined. In example the timing of the injection for each cylinder is known and thus timing of the injection pulse for the respective cylinder can be known, so the timing (relative or absolute) of other pulses identified as intake/exhaust valve closing of respective cylinders can be determined.

Example Method

This example applies to engine systems with smart injectors, that is to say as well as having at least an accelerometer on them or associated with them, they are equipped with a microprocessor or chip. There are communication lines with the ECU to allow the smart injector i.e. processor/chop to communicate with each other.

In Step 1: The Engine controller/ECU sends an instruction to the injector indicating it wishes to receive the time when the exhaust valve (e.g. in respect of the cylinder for which the respective fuel injector injects). The injector processor may set or reset resets a timer on receipt of this message. In Step 2: The injector receives the signal from the accelerometer and in Step 3: the injector processor analyses the signal e.g. by applying respective algorithm including optionally filtering to detect (i.e. home in on and isolate) the vibration pulse with respect to the exhaust valve closing, in the recording. In step 4 the injector then sends the time that the pulse with respect to the exhaust valve closing is detected. Step 5: the injector replies with the time between receipt of the instruction in step 1 and the point in the recording where the exhaust valve closing was detected.

Claims

1. In an internal combustion engine having one or more cylinders, each cylinder having a fuel injector adapted to inject fuel there into, and where said injector includes an accelerometer associated therewith, a method of determining the closing time of an exhaust valve and or inlet valve of a cylinder comprising:

a) obtaining a signal from one or more of said accelerometers;

c) determining the timing of said pulse(s) of step c).

2. A method as claimed in claim 1 including performing the additional step of:

3. A method as claimed in claim 1 wherein step d) is performed from ECU or other engine data.

4. A method as claimed in claim 1 where step d) is performed by identifying dominant regular pulses from said accelerometer signal.

5. A method as claimed in claims 2 to 4 comprising determining the timing of two intermediate pulses having the largest magnitude between the times of step d) and taking the first as the exhaust valve closing time and/or the second as the intake valve closing events for the respective cylinder on which the accelerometer signal is determined.

6. A method as claimed in claim 2 to 5 including identifying any intermediate pulse which is determined to be an injection event in another cylinder, and in step (i) excluding said pulse in the determination.

7. A method as claimed in any preceding claims wherein accelerometer pulses are analysed in terms of their duration, relative timing, magnitude or frequency spectra in order to classify pulses as due to any one of the following: injection, intake valve closing and outlet valve closing.

8. A method as claimed in claim 7 including applying frequency analysis to said pulse (s) to distinguish between two or more of the following cylinder events of injection, intake valve closing and outlet valve closing.

9. A method as claimed in any preceding claim including analyzing pulses and their timing with respect to one or more accelerometers on other injectors and using this data together in step b) and or step d) additionally.