FJELD OF THE INVENTION

[0Q01] The present invention relates to a system and method for managing the operation of an engine. More specifically, the present invention relates to a system and method for measuring undesired torsional vibrations in an operating engine and managing the operation of that engine to control those torsional vibrations.

BACKGROUND OF THE INVENTION

[0002] Internal combustion engines experience torsional vibrations during their operation. As used herein, the term "torsional vibration" is intended to comprise the undesired accelerations and decelerations experienced at the output of the engine due to intermittent loading and unloading of the engine during operation of the engine. The impulses resulting from the firing of the cylinders in an internal combustion engine are the major source Qf torsional vibrations, however other components and systems also contribute to torsional vibrations, including the opening and closing of the engine's valves by the camshafts, the operation of accessories such as power steering pumps and/or alternators, etc.

[0003] Torsional vibrations are generally undesired as they create strain on engine components, increase operating noise and vibration, decrease the operating lifetime of accessory drive belts, etc. Further, if the torsional vibrations occur at a frequency close to a natural resonance frequency of the engine, or engine subsystem, the engine can resonate and suffer damage to its components from that resonance.

[0004] To reduce torsional vibrations, it is known to include dampeners and/or overrunning decouplers on the accessory drive system of the engine and/or to alter the design and shape of camshaft and/or crankshaft sprockets. Such known systems have been shown to reduce torsional vibrations in operating engines, albeit with various degrees of success.

[OO05] Engine designers also test engines for resonance during expected operating conditions and will redesign engine components or add other components in attempts to reduce the likelihood of the onset of such resonance during expected engine operating conditions. However, performing a successful analysis and/or redesign can be difficult or impossible to achieve owing to the large range of possible operating conditions for an engine, the large array of possible combinations of accessories which can be attached to an engine and/or the combinations of the various possible operating conditions and loads of those accessories, etc. As changes to any one of these parameters can alter the resulting likelihood of the onset of resonance, it is very diffi cult or impossible for an engine designer to achieve a high level of confidence that resonances will be avoided.

[O006] Further, to date all attempts to reduce torsional vibrations and/or to avoid the onset of resonance have merely comprised altering each device which is a source of torsionals, such as adding an overrunning decoupler to the alternator, etc.

[O007] In other circumstances, it can be desired to increase the amount of the torsional vibrations experienced by an engine. For example, in engines e mploying variable valve timing systems operated by pressurized hydraulic fluid, it is known to employ a pump to pressurize the fluid which is powered by the torsional vibrations of the engine. While this system operates acceptably in most conditions, at low engine loadings and speeds, such as at idle conditions, there may not sufficient torsional vibrations to operate the pump at the required output levels. It is known in these circumstances to intentionally alter a sprocket on the camshaft timing system to induce the necessary levels of torsional vibration at operating points which would otherwise be problematic. [O008] Accordingly, despite the use of the above-mentioned devices and methods of reducing the torsional vibrations experienced by an engine, engines can still suffer from undesirable amounts of torsional vibration which shorten the lifetime of the engine and its related components and accessories. Further, it can be desirable in some circumstances to increase the level of torsional vibrations experienced by an engine.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide a novel system and method of measuring torsional vibrations in an engine and managing the operation of the engine to control those torsional vibrations which obviates or mitigates at least one disadvantage of the prior art.

[0010] According to a first aspect of the present invention, there is provided a system for measuring torsional vibrations in an engine and managing operation of the engine to control those vibrations comprising: at least one sensor to output signals representing the angular position of a rotating member of the engine with respect to time; a processor to receive the signals from the at least one sensor and to process the received signals to characterize torsional vibrations occurring in the engine, the processor outputting at least one signal to manage the operation of the engine to control the characterized torsional vibrations. [0011] Preferably, the processor further analyzes the received signals to detect resonance conditions in the engine, the processor outputting at least one signal to manage the operation of the engine to reduce detected resonance. [0012] According to another aspect of the present invention, there is provided a method of managing the operation of an engine, comprising the steps of: (i) determining the angular position of a rotating member of the engine at known time intervals; (ii) processing the determined angular positions to determine torsional vibrations in the engine; and (iii) altering at least one operating parameter of the engine to control the determined torsional vibrations. [0013] The present invention provides a system and method to manage the operation of an engine to substantially avoid undesired operating conditions resulting from torsional vibrations. The system and method monitors, substantially in real time, the operation of the engine to detect the occurrence or onset of undesired operating conditions, such as relatively large torsional vibrations or resonance within the engine or unacceptably low levels of torsional vibrations in certain engine operating circumstances. When an undesired operating condition is detected by the system and method, the system and method alters one or more engine operating parameters to reduce or eliminate

the undesired operating condition, increasing or decreasing the torsional vibrations, and/or reducing resonance, as desired.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the attached Figure 1 which shows a schematic representation of a system for measuring torsional vibrations in an engine and managing operation of the engine to control those vibrations in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The assignee of the present invention has developed a novel sensor system and method for measuring the angular position and/or speed of a rotating member. Aspects of this system and method are described in detail in co-pending U.S. provisional patent applications: Rotational Position Sensor Based Engine Controller System, serial no. 60/621 ,767, filed October 25, 2004. Vehicle Control System And Method, serial no. 60/631 ,756, filed November 29, 2004, Engine Controller System and Method Employing High Speed Angular Position Sensor, serial no. 60/652,722, filed February 14, 2005, Method and System for Starting Or Re-Starting An Internal Combustion Engine Via Selective Combustion, serial no. 60/711 ,872, filed August 26, 2O05 and co-pending U.S. patent application, Rotational Position Sensor Based Engine Controller System, serial no. 11/146,727, filed June 7, 2005, the contents of each of which are incorporated herein by reference.

[0016] As described in these incorporated references, the novel sensor system can include a digital processor, an A/D converter (which can be integral with the processor or separate) and one or more sensors, preferably employing two pairs of oppositely orientated magnetic sensors, each pair arranged at right angles to one another, such as is available in the model 2SA-10 Sentron sensor manufactured by Sentron AG, Baarerstrasse 73, 630O Zug, Switzerland. [0017] The sensor is located adjacent at least one dipole magnet which rotates with the rotating member and, as the magnetic field from the dipole

magnet rotates with the rotating member, the output from each sensor pair measuring the dipole's field is a sinusoid voltage signal, with the output of one sensor pair being ninety degrees out of phase with the signal of the other sensor pair. The sinusoid voltages are converted to digital values by the A/D converter and provided to the processor which calculates the arctan (tan ^"1 ) of the sinusoidal voltages to determine the angular position of the rotating member. [001S] Specifically, if the angular position of the rotating member is α, and the output voltage from the first sensor pair is Vi and the output voltage from the second sensor pair is V ₂ , then α can be determined from:

V ₁ = cos(a) V ₂ = sin(α)

V ₂ sinfα)

= tan(α)

V ₁ cos(a) α = arctanf -^- ) v/ where

For (Vi>0, V ₂ >0), α^arctanfVaΛΛ);

For (V ₁ =O, V ₂ >0), α=90°;

For (VK 0), α= 180°+ arctan (V ₂ ZV ₁ );

For (V ₁ =O, V ₂ < 0), α=270°; and

For (Vi>0, V ₂ <0), α= 360°+ arctan(Va/Vi).

[001 Θ] The novel sensor system described above can determine αto better than one degree of accuracy at rotational speeds up to at least 8,000 RPM. Further, if an appropriate algorithm and/or processor is employed in the novel sensor system, α can be determined effectively in real time, or near real time. [002O] While the present invention preferably employs the angular position sensor systems and methods described in the above-mentioned pending patent applications, the present invention is not so limited and, as will be apparent from the following description, any suitable sensor system or method which is capable of providing information indicating the angular position of a rotatable member of an engine, when that engine is operating at normal operating speeds can be utilized.

[O021] In particular, the present invention can instead employ the method and system of processing the output of sensors taught in the above-mentioned U.S. Provisional Patent Application, "Engine Controller System and Method Employing High Speed Angular Position Sensor", serial no. 60/652,722, filed February 14, 2005.

[O022] In laboratories and on test vehicles, delicate and expensive systems such as those manufactured and sold by Rotec GmbH, are employed to measure torsional vibrations. While such systems can accurately measure torsional vibrations, these systems are too expensive and/or fragile to be employed in systems to manage the operation of real world engines. Further, such systems do not provide a sufficiently real time analysis and/or output which can be used to manage operation of an engine.

[O023] The present inventors have now determined that, in contrast to the above-mentioned systems used for measuring torsional vibrations in a laboratory, with the determined values of the angular position α of the rotating member provided by the novel sensor system, or any other suitable sensor system, torsional vibrations of an engine can be economically and accurately determined during normal operation of the engine.

[O024] Torsional vibrations can be determined from α in a variety of manners. For example, α can be determined as described above and stored in an array for a given period of time, such as one engine revolution. Then, the average speed of the engine for that given period of time can be determined and, from this determined average speed, an array of corresponding ideal angular positions (i.e. - angular positions which would correspond to rotation through the one revolution with no torsional vibrations) can be constructed. Each array will have the same number of entries which correspond to the angular positions of the rotating member at the same sample times.

[0025] If the array of ideal angular positions is A[n] and the array of measured (e.g. -actual) angular positions is B[n], then the time difference at each sampled position (i.e. - how much time the rotating member leads or lags its ideal angular position) between the two positions can be determined from

where S is the sampling rate, in samples per second.

[0026] The momentary value of zero to peak torsional vibrations (in degrees) can be determined from

_X[n} = ^M ₃₆₀ where R is the time required for one revolution of the rotating member (in seconds).

[0027] As will be apparent to those of skil 1 in the art, torsional vibrations can be determined from measured values of α in a variety of other manners and the present invention is not limited to any particu lar mathematical process for doing so.

[0028] Once X[n] or similar values have been determined, the present invention can be employed to manage the operation of the engine. For example, sets of X[n] can be analyzed in the time and/or frequency domains to detect resonance in the engine. Similarly, the magnitudes of the determined values of X[n] can be examined to determine when trie engine is operating in undesired conditions, etc.

[0029] Figure 1 shows an embodiment of an engine management system 100 in accordance with the present invention used with an engine 104. Engine management system 100 includes a processor 108, which can comprise any suitable special purpose or general purpose processor which is suitable for automotive control uses. In a present embodiment of the invention, processor 104 comprises a Texas Instruments TMS320F2810 DSP processor and other standard electronic components necessary to interface signals to and from engine 104, although other dedicated or special purpose processors, microcontrollers or other computing devices can be employed, as will be apparent to those of skill in the art. It is also contemplated that processor 108 can be a substantially conventional engine control unit (ECU) which performs engine management functions in addition to the torsional vibration measurement and control functions described herein.

[0030] Management system 100 further includes at least one sensor 112, such as the above-mentioned 2SA-10 Sentron sensor, to determine the angular position of a rotating engine member, or accessory attached to the engine. [0031] In the illustrated embodiment sensor 112 is used by system 100 to determine the angular position α of the crankshaft 116 of engine 104. While this embodiment employs signals from sensor 112 relating to rotation of crankshaft 116, it is also contemplated that processor 108 can utilize signals from sensors 112 relating to the rotation of other engine components, such as camshafts, oil pumps, etc. and/or engine accessories such as alternators, air conditioning compressors, etc. if desired.

[0032] In operation, processor 108 operates on signals received from sensor 112 to determine if engine 104 is operating in an undesired manner, such as in a resonance condition or with unduly high or low magnitudes of torsional vibrations.

[0033] If an undesired engine operating condition is detected by processor 108, system 100 can alter one or more operating parameters of engine 104 to control the torsional vibrations and/or to inhibit resonance. For example, if processor 108 is also functioning as an ECU for the engine, processor 108 can provide a signal 120 to an actuator 124 to alter an engine operating parameter to control the torsional vibrations and/or reduce, or preferably eliminate, a detected resonance condition in engine 104. If processor 108 is a separate processor, processor 108 can provide a signal to a conventional engine control unit (ECU) 136 to cause ECU 136 to alter an engine operating parameter to control the torsional vibrations and/or reduce, or preferably eliminate, a detected resonance condition in engine 104.

[0034] Examples of engine operating parameters which can be altered by processor 108, either directly or indirectly, include (without limitation): the phasor between the inlet camshaft 128 and the exhaust camshaft 132; the engine RPM; the loading on the engine; fuel injection and/or ignition timing (advance/retard); etc.

[0035] Loading on engine 104 can be increased or decreased by altering an accessory load, such as increasing the current to the alternator field coils or

engaging or disengaging an air conditioner compressor, etc. As yet another example, processor 108 can provide a signal 144 to a device 148 on a serpentine drive belt, or other accessory drive, to alter the load on engine 104 to control torsional vibrations and/or reduce or eliminate detected resonance in engine 104. Or, signal 144 can be provided to an automatic transmission to have the transmission change gears to change the operating speed of engine 104.

[0036] Device 148 can be any device whose operation can be modified by signal 144 to alter the operating conditions of engine 104. For example, device 148 can be a tensioner whose dampening force can be altered by signal 148. As yet another example, device 148 can be a starter generator whose operation can be altered by signal 144 such that the starter generator can be switched between operating conditions wherein it is a load (operating as a generator) on engine 104 and operating conditions wherein it is a booster (operating as a motor) on engine 104 and/or wherein it is free-wheeling (not substantively loading or boosting engine 104).

[0037] While engine 104 is illustrated as being a DOHC engine, the present invention is not so limited and if engine 104 is single camshaft engine, actuator 124 can alter the phasing between that cam shaft and crankshaft 132 or perform any other adjustment, such as those described below, to control torsional vibrations and to reduce, or preferably eliminate, a detected resonance condition in engine 104.

[0038] If processor 108 is a separate processor, processor 108 can provide a signal to a conventional engine control unit (ECU) 136 to operating parameters of engine 104.

[0039] System 100 can operate to alter one engine operating parameter, or appropriate combinations of operating parameters. For example, system 100 can alter the camshaft phasors and the fuel injection timing to control torsional vibrations.

[0040] As will now be apparent, system 100 operates to manage the operation of engine 104 to substantially avoid undesired operating conditions relating to torsional vibrations. System 10O monitors, substantially in real time,

the operation of engine 104 to detect the occurrence or onset of undesired operating conditions, such as relatively large torsional vibrations or, in some instances insufficient torsional vibration levels, and to reduce or eliminate resonance within engine 104. When an undesired operating condition is detected by system 100, system 100 alters one or more engine operating parameters to reduce or eliminate the undesired operating condition. [0041] It is also contemplated that, as system 100 has very accurate information relating to the angular position α of the crankshaft, or other measured rotating member, this information can also be used by other engine management processes, instead of the conventional sensors, such as inductive pickups of toothed gears on the crankshaft, etc. In such a case, processor 108 can either replace the conventional ECU which would operate on such conventional sensor outputs, or processor 108 can provide a signal to the conventional ECU, which signal replaces or augments the signal from prior art conventional signals.

[0042] The above-described embodiments of the invention are intended to be examples of the present invention and alterations and modifications may be effected thereto, by those of skill in the art, without departing from the scope of the invention which is defined solely by the claims appended hereto.